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Echinodermata! Starfish! Sea Urchins! Sea Cucumbers! Stone Lillies! Feather Stars! Blastozoans! Sea Daisies!Marine invertebrates found throughout the world's oceans with a rich and ancient fossil legacy. Their biology and evolution includes a wide range of crazy and wonderful things. Let me share those things with YOU!

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    20111021-143924-Canon PowerShot G12-0720.jpg
    Awesome pic by Mevallee
    Let's just admit it. Poop is awesome. Its natural, all animals do it and its frakkin' hilarious. PLUS its biologically important to everyone so we can't just stop talking about it..

    I have written about the importance of the poop of other echinoderms in prior posts-particularly this one about green sea urchins (Strongylocentrotus droebchiensis)

    Recent research has brought a powerful spotlight on not just the ecological, but the overall, importance of sea cucumbers to the environment.  Sea cucumbers occur all over the world and at all depths. Often, when present, they are abundant or at least a significant part of the fauna present.

    But the key dynamic present to their importance is that they cycle or process what they eat and what they defecate contributes to the health of the habitat they inhabit.

    1. Sea Cucumber poop buffers against ocean acidification on coral reefs
    2008-11-26 SAPONA WRECK - Sea cucumber poop
    Image by scuba.linda
    A paper by Kenneth Schneider (Stanford University) et al., including echinoderm researcher Maria Byrne's  was published in the Journal of Geophysical Research (2011. 116: G04032)  received a lot of press, such as this account (in Australian Geographic) and this one (which has an interview with Byrne) about how sea cucumber "poop" is important to geochemical processes on a coral reef.

    I realize that articles about "coral reefs saved by sea cucumber poop" sound kind of silly on the surface, but read and understand below.... (note also the Journal of Geophysical Research? Important stuff gets put in there.)

    Coral has to develop or accumulate calcium carbonate, which is the mineral used to compose coral skeletons, at an equal or better than the rate at which the coral loses calcium carbonate via erosion, natural dissolution, etc.

    A survey of the sea cucumbers Stichopus herrmanni and Holothuria lecuospilota in One Tree Reef, Australia showed that the sea cucumbers could digest and dissolve so much of the adjoining sediment and rubble (ie the sand) that they actually contributed up to 50% or MORE of the total amount calcium carbonate dissolved over a night time. Presumably this was made available for coral to use for reef development.

    Chemically, calcium carbonate is very alkaline or basic. So, sort of like an antacid. What do you do when you have stomach acids that are misbehaving? Drop some of those tablets to "cancel" out the acidity.

    So, sea cucumbers contribute calcium carbonate to the coral reef's "chemical budget". They act like a natural antacid to neutralize other acidic environmental sources. Under normal conditions, there's an equilibirum. The abundance or number of sea cucumbers can affect this.

    Thus, in theory,  MORE sea cucumbers might produce so MUCH alkalinity (or "basic" poop to the water) that conceivably they could function as a control or at least a buffer against increases in more acidic sea water.  This obviously is important when you consider ocean acidification resulting from global warming.  Sea cucumber poop is an important part of helping to keep the geochemical balance of a coral reef in equilibrium.

    2. Sea Cucumbers EAT tasty bottom poop and clean it up!  
    Poop is processed into useful nutrients! Over abundance of nutrients (i.e eutrophication) is broken up by sea cucumber feeding!

    A recent paper in PLOS one from Thomas MacTavish and colleagues in New Zealand studied a local sea cucumber Australostichopus mollis and how its presence affects the nutrient cycling in its surroundings.

    MacTavish and his colleagues studied a nutrient-rich environment covered by algae, mussel feces and other nutirent-rich goodies. Under normal circumstances, these would build up bacteria, ammonia and other factors creating conditions that contribute to the growth of  algae, which ultimately chokes everything else out (aka eutrophication).

    But you put a sea cucumber into these settings? They LOVE it! They eat and all sorts of good things happen:
    • Bacterial abundance increases
    • Organic material (i.e., the goo) begins to decompose more quickly
    • Organic materials are redistributed from the marine sediments into the water
    Sea cucumbers help to break down organic material and redistribute the nutrients! The poop is an important part of that process.

    This has implications....

    3. Eating good poop cleans up aquaculture environments
    IMG_0694.jpg
    Image by Jeremy and Christine
    Papers such as the one above, this one focusing on the tropical Stichopus japonicusand this one on Parastichopus californicus in cold-temperate waters all show that many people have picked up on the fact that sea cucumbers are useful animals for breaking up environments that suffer from being choked in nutrients.

    Eutrophication-the overabundance of nutrients resulting in undesirable growth of algae and hypoxia-is a common problem in aquacutlure ponds.
    Sea Cucumber aquaculture
    Image by Smartfish-ioc
    But putting a sea cucumber into the mix? A critter that LOVES organic nutrients and gooey stuff like that?  It would go to town! Cleaning up the bottom and cycling those bottom nutrients...  Seems like a win-win solution for cleaning up the bottom of say a fish or mussel farm where feces from the animals accumulate in huge amounts.

    So yes. Sometimes sea cucumbers eat poop. And then poop poop, which is probably "cleaner" than what went in the first place...

    4. Sea Cucumber poop is good for plants (mangroves, seagrass, etc.), which are part of a healthy ecosystem
    P7140072.JPG
    Image by Eunice Khoo- "Mermate"
    So, by this I don't just mean ONLY the poop-but the animal digesting and then processing the sediment.  This follows everything from the above-they break down organic detritus and make the nutrients available to the water column preventing hypoxia and other bad things going down in the sediment...
    (its a great video, but I didn't enter the description!)

    The nutrient cycling role of sea cucumbers has been observed as an important part of ecology. One post I put up awhile back shows that the presence of sea cucumbers leads to more productive sea grass!  and thus a more diverse and healthy tropical ecosystem.

    Think of them as earthworms! go through the bottom sediments, eat all the organics and leave the sediment.. that's sea cucumber poop!

    5. Deep-Sea Cukes have pretty diverse microbial faunas that live in their guts! (and thus their poop!)

    Deep-sea sea cucumbers perform very much the same kind of function as the shallow water ones. They live in much finer mud and are often rained upon by nutrients from the surface. Many of these critters, such as Molpadia (shown here) live buried in the mud.

    Most of their overall morphology seems devoted to processing mud..in one end and out the other...
    We add to that another spin!  There are whole microbial faunas that live INSIDE their guts! Go to these past posts to read more about them..

    Remember just how abundant these can be in the deep sea. Some occur at a density of 220 individuals per square meter!

    How much of this fauna comes out in their poop?  How does it contribute to the local environment?

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  • 06/18/13--22:34: Feather Star Color Bonanza!
  • Feather Star
    A key lime colored crinoid by Frederique Jaffeux, South Ari Atoll in the Maldives
    This week, some brightly, eye-jarring crinoids in mind-blowing COLOR! What are crinoids, aka feather stars?  They are echinoderms that hold their feathery arms up in the water and pick food out of the current as it flows through/past them!  Want to learn MORE about crinoids? Visit this awesome site by Dr. Chuck Messing!

    Purple and white feeding fan of a feather star from the Maldives!
    Crinoid Fan
    Image by Bil Stohler
    Here-some brightly colored blue feeding structures called pinnules are seen on the arm...
    blue crinoid
    Image by mimimoyer
    A gorgeous crinoid from Okinawa withdrawn into itself
    Feather star - in protection mode!
    By Okinawa Nature Photography
    A stunning green crinoid from Okinawa.
    ( Oxycomanthus bennetti ) feather star- okinawa
    By Okinawa Nature Photography (Shawn Miller)
    Stunning orange..
    Feather Star
    Image by Henry and Tersia. Borneo.
    Black and White on a red sea fan.
    Crinoid on Seafan
    Image by Randapex
    Macro of Blue Oxycomanthus arms. fr. Bali.
    Just a crinoid (Oxycomanthus sp.)
    Image by Arne Kuilman
    Blue crinoid in repose fr. Indonesia.
    Koala Crinoid 2033
    Image by Courtney Platt
    Black & White Crinoid from the Philippines
    black 'n white feather star
    Image by Mona Dienhart & Chris Lebas

    There is a fish in this picture! Can you spot it?
    Crinoid clingfish (Discotrema crinophila)
    Image by Arne Kuilman
    A crinoid in a lovecraftian pose!
    Crinoid Flexing
    Image by Eddy Wong

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    Today: BROODING Juveniles!  Wait, What? No, NOT like this

    Twilight
    Seriously! This is one of the top images that comes up in a Google search for "brooding"
    I meant Brooding juveniles like THIS!
    Diplasterias brandti
    from the Smithsonian NMNH USARP
    In other words, these are "baby" starfish that are cared for by the mother until they are ready to head off ont their own. Parental investment resulting in a succesful offspring. 

    Sometimes starfish (and indeed most echinoderms) can appear kind of alien. No head. Mouth on the bottom. 5 part radial symmetry. Strange adaptations. All kind of weird sometimes.

    So, I suppose its appropriate that the WEIRDEST of ALL echinoderm (and starfish) behavior is that starfish have this almost mammal-like (or at least, vertebrate like) behavior!!   Some starfish species will actually brood and carry little starfish just like the cutest little furry thing you can think of!

    Now, most starfish have a fairly straightforward reproductive cycle.

    Eggs and sperm are ejected from the males and females-they fertilize and go on to form larvae which swim in the water developing through different stages, eventually eventually settling down onto the bottoms and growing up to become proper "adult" starfish.

    But many starfish species stray from that typical cycle, and somewhere between the time the sperm fertilize the eggs and the settled "babies" are established the whole life cycle CHANGES to give you this:

    Yes. Tiny baby or small juvenile starfish which are held by the mother around the mouth! (this varies as we'll see). Why do some starfish do this?  And not the more 'typical' behavior?

    Scientists have known about brooding behavior in several species of starfish since the 19th Century but only recently has there been the extensive observation and insight to finally piece together the complete story!

    The Story of Leptasterias polaris
    Information herein is based on a paper by Jean-Francois Hamel and Annie Mercier at Memorial University in Newfoundland. which you can find (here) in Biological Bulletin from 1995 (vol. 188: 32-45)

    They studied the large, Arctic/subArctic 6-rayed starfish Leptasterias polaris which occurs in the North Atlantic, Arctic and North Pacific Oceans.
    Image by Claude Nozeres  from the Canadian Registry of Marine Species
    Hamel and Mercier's paper exhaustively studies L. polaris' complete reproductive cycle, which pretty thoroughly documents the reproductive behavior in this species.  Bear in mind, that this starfish has been known since 1842 and yet our knowledge of its reproduction has only come to us recently (published in 1995)!

    Information on brooding remains of interest-but the behavior and its evolution is poorly understood.

    1. PSEUDOCOPULATION
    Figure 1 from Hamel & Mercier 1995
     As a prelude to the actual spawning there are massive aggregations of these animals. They're involved in an unusual behavior known as pseudocopulation. There's no penetration or combination of sexual organs, nor is there any actual spawning. The animals all just get together into a big pile. Sort of preparation for the main event.

    Bear in mind, OTHER than during mating season (November to February), these animals all typically ignore or even avoid one another.

    Many echinoderm species practice pseudocopulation which I've written about here. Its not always clear why different species pseudocopulate. But one thing seems clear: It helps the chances of their sperm and eggs get together.

    2. Spawning! There were no pics of actual Leptasterias spawning, so here instead is a closely related Asterias. I have discussed this spawning on armtips position here. It is observed widely across cold water and tropical species.
    spawning starfish
    Image by Tom Ashton
    Spawning in Leptasterias polaris males begins as the water gets cold, about 2 degrees C. 

    Sperm (male cells) are negatively buoyant, or in other words, they sink to the bottom and form sort of a film. The sperm then go dormant until they come into contact with the female's eggs..

    3. The Female Pinwheel formation. Stimulated by the males, and following the deposition of sperm on the bottoms, the females proceed to eject the eggs onto the sperm so that fertilization can proceed.

    The deposition of the eggs onto the sperm re-activates the sperm allowing them to combine and fertilize.

    During this phase, the females adopt this "pinwheel" formation
    From Mercier's L. polaris site
    Here (from Figure 5 in Mercier & Hamel) we see a close up of eggs UNDER the female in C. Which then grow up into the cute as the dickens starfish in D.  Growth was after about 5 and half months.
    4. After fertilization, development proceeds. Here's a summary panel of the different stages. The top row is the developing embryo. It continues through different stages until it reaches "J." 

    At that point the animal is practically ready to move off on its own..
    Figure 9 showing development from embryos to small starfish 
    Interestingly, Hamel & Mercer found that the development proceeded on its own if the embryos were unbrooded.  They suggest that brooding is behavior which protects the embryos/juvenile starfish from debris and other materials. Animals observed in the field were clear of excess materials.

    Protection was also a likely consideration since unprotected embryos/juvenile starfish were rapidly devoured by sea urchins or other grazing animals if they were not protected by the adult. 


     The whole cycle is sumarized in this convenient cartoon!
    Figure 4 from Hamel & Mercier 1995
    There were MANY more details! If the topic of brooding interests you I urge you to check it out!

    BUT That's NOT the end of it!  

    5. Brooding is diverse.  SEVERAL different species of sea stars brood. Almost all of them are either cold-water species, living in the deep-sea or at the poles. Sometimes brooding is in temperate water species.. But typically not in the tropics.

    Brooding also takes different forms. The oral 'mouth' or gastric brooding mode is but one kind. Here is Diplasterias from the Antarctic!  MANY starfish in the Antarctic brood juvenile starfish!
    Diplasterias brandti
    from the Smithsonian NMNH USARP
    For example, in the suspension feeding brisingids, the Antarctic species Odinella nutrix, broods babies  in special chambers made from the arm spines present between each of the arms.
    There is the strange Japanese/Russian/North Paciic Trophodiscus (go here to see more) Juveniles are brooding on the TOP of the animal among the spines (called paxillae) that compose the surface of the disk.
    Here is a living specimen. Image by colleague Yoichi Kogure!
    Close up
    And then there's Tosia neossia, recently discovered in Australia. This species broods but without actually keeping the babies physically on the body. They are kept spread out near the animal... See the orange dots in the picture below?  That's the juveniles...  I wrote about this species here.
    Here's the tiny Tosia crawling larvae!
    And in the deep-sea, there is the weird "sea daisy" Xyloplax!
    And that's not to mention brooding in sea urchins, ophiuroids, crinoids and sea cucumbers! and MANY other invertebrates!  Starfish brooding is just the tip of the iceberg!

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    Magnificent Ascidian
    Image by Leander Wiseman
    Today, a little off topic time for some tunicate love!

    For those who are not familiar, tunicates are actually members of the same overall group to which humans and all other vertebrates belong! A subgrouping, called the Tunicata within the larger phylum Chordata. Honestly, the relationship is pretty basic info which you can find with a quick Google search

    Most times, tunicates are small, out of the way or encrusting (i.e., covering surfaces over a wide area) but can be very abundant, carpeting areas until nothing else grows there..such as this one (Botrylloides diegensis) which is an invasive in San Francisco Bay from Asia.
    Chain sea squirt (Botrylloides diegensis)
     Image by Luis A Solórzano, KQUEST
    Under many conditions, tunicates are ugly and kind of bland colored things that are common components of fouling communities. Its species such as this one which earn the oh so lovely common name "sea pork"(Amaroucium californicum). And so, they get a bad rap. 
    Amaroucium californicum
    image by Jkirkhart35
    But tunicates are often gorgeous and attractive animals. PLUS, they do weird and unusual (if kinda creepy) things! Let's go see! 

    1. Some Basics
    This shows two siphons: one is where water goes IN and the other is where it goes OUT.

    Kidney closeup (Polycarpa aurata)
    Image by Arne Kuilman, from Anilao, Philippines
    Food gets caught in the "Pharyngeal basket" (=the "filter" for its filter feeding) where it gets moved down to the stomach. A pretty simple overall anatomy. But note, it has well-developed organs that you would find in a proper animal.  This is important later...
    From the Marine Life Information Network
    This gives you a general idea of the animal as a whole (not sure if this is the exact same species but you get the general notion)
    Sea Squirts
    Image by Prilfish
     Basket Close ups! 
    Green entrance
    Image by Steve de Neef
    Cross section! the space between the 'tunic" and the feeding basket
    IMG_2969
    Image by "stupidhead"
    2009_0502_111050
    Image by Star Tsai
    INSIDE the basket!
    Alien tunicate, Eastern Fields, Papua New Guinea
    Image by Eric Cheng
    Tunicate-1
    Image by Christian Loader
    Roots
    Image by Steve de Neef
    2. Some Diversity... 
    Some tunicates are individuals
    _MG_4419
    Image by bybegone
    Whereas other forms are colonial...
    A ball of Bluebells
    Image by Patrick Nilsson

    Botrylloides magnicoecum from Australia. And yes, those are apparently the REAL colors.
    Magnificent Ascidian
    Image by Leander Wiseman
    Botrylloides leachi from Australia
    Leache's compound ascidian - Botrylloides leachi
    Image by John Tumbull
    clear tunicates 2 edited
    Fantastic image by Pat Sinclair
    Other tunicates are more....unusual in appearance (I think these are solitary)  BEHOLD! Sea Tulips! Pyura spinifera from Australia!
    Sea Tulips
    Image by Richard Ling
    Here's only a few...
    Sea Tulips
    Also by Richard Ling
    Here's a LOT of them
    Sea Tulips
    Image by Richard Ling
    Another stalked tunicate, Oxycorynia fascicularis from Anilao in the Philippines
    Oxycorynia fascicularis, Stalked Tunicate, Anilao, Philippines
    Image by Optical Allusion
    Stalked GREEN tunicates! Same species? Oxycorynia fascicularis
    Stalked green tunicates
    Image by Mer Mate-Eunice Koo
    And although I've been focusing on shallow water, I can't get past tunicates without the obligatory showing of the famous DEEP-SEA predatory tunicate (Megalodicopia hians) !! The IN siphon is modified into a mouth and the OUT siphon kicks out the tunicate poop!   Let's let the British narrator take us away!


    3. The predatory tunicate is a great segue for the vice versa! People EAT tunicates.As I've outlined here Its called the "sea pineapple" among other things in Asian cultures, but different species (called 'sea violets') are eaten by Europeans..
    Sea squirts
    Image by sjbutterfield2
    MMmm........tunicates and kimchi....
    Sea Pineapple
    Image by Mark Deibert Photography

    4. Tunicates are a little creepy 
    If tunicates have similar enough tissues (historecognition) ie. are similar enough two physically different individuals can physically FUSE together.

    Why say it, when you can SHOW it?

    the description from the video:
    This video shows a fusion event in progress between compatible individuals of the sea squirt, Botryllus schlosseri. At the beginning, terminal parts of vasculature, called ampullae, which surround the colony, have come into contact (one colony is on the top right, the other on the bottom left, out of the field of view). The ampullae push into each other repeatedly, and finally the cell layers between two ampullae fuse, and results in both individuals sharing a common circulation. 
    Fusion can best be seen on the top left, but occurs in several places in the region of interaction. The decision to fuse or reject is based on whether the two colonies 'match' each other, analogous to how humans accept or reject transplants.
    See this essay for more.  But bear in mind, tunicates may look simple like sponges-but they aren't! 

    Sponges don't have tissue, so those videos where they grind em' up and they get back together?

    Not that hard for animals that are still essentially just colonies of cells. Proper ANIMALS with tissues don't typically do stuff like that.  The fusion shown in tunicates above?  That's like you and your family, suddenly fusing into one big amorphous pile. Squicky, eh?

    Go here to learn more about this.

    5. Where can I learn MORE about tunicates?
    *Did you know that tunicates accumulate the metal Vanadium in their body tissues? go here to learn more.
    *The Dutch ascidian Site! 
    *The Tunicate Web Portal! 
    *Will tunicates be used as biofuel? 
    and my colleague Jarrett Byrneswrites a blog that often involves tunicates!

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    from Wikipedia!
    SEA URCHINS! Who doesn't love em? The spiny balls of the sea! We eat em! They're important to marine ecosystems all around the world! They're often visually stunning and they do all sorts of neat and wacky things!

    But sometimes I get ahead of myself and forget the basics! Basic questions that everyone has aren't often obvious and so this week a quick summary overview:  What and How do sea urchins eat???

    Urchins feed primarily with a unique jaw-like structure known as Aristotle's lantern. It looks like this in most urchins but is modified in so-called "Irregular" urchins such as sand dollars, sea biscuits and etc. A bit about this here.
    Here is the jaw in action, with the tips being extended from the mouth as the animal rasps away on the bottom it lives on...

    Believe it or not. Sea urchins have among the most diverse feeding modes within the Echinodermata. Here is a roundup... COUNTING DOWN!

    5. Herbivores and Grazing
    This is the one everybody knows about and the feeding mode with which most people are most familiar. Many sea urchins prefer kelp and various other seaweeds and marine "plants." There are several species found in cold-temperate water habitats.. California, New Zealand, Chile.. to name a few, and all these places have sea urchin species in abundance.

    Here is the famous purple sea urchin, Strongylocentrotus purpuratus engaged in some kelp feeding!

    Urchins and Kelp
    Image by Todd Jackowski
    Urchins are ecologically important in kelp forests. Removal of predators (and control of the population) can lead to a circumstance known as "urchin barrens" where sea urchin abundance goes out of control. In those circumstances, even sea urchin poop can become a serious consideration (here)

    Here is a nice Shape of Life video that shows feeding by the Purple sea urchin Strongylocentrotus purpuratus.
    Echinoderms: Urchin Time-lapse: Eating Kelp from Shape of Life on Vimeo.
    Note that while many sea urchins feed primarily on kelp, they are not obligated to do so.  Their diet permits them some nutritional flexibility.....

    4. Omnivory and Scavenging

    Most people (even several biologists) don't realize that sea urchins can be pretty flexible in their diet. If kelp isn't available, they will obtain whatever nutrition happens to be available.

    Some large examples of food here, but feeding also includes microalgae (such as diatoms), encrusting algae, moss animals (i.e. bryozoans) and etc.

    Here we have what Strongylocentrotus spp. in the Arctic or sub Arctic feeding on what looks like a wayward or moribund jellyfish..
    Sea urchins feeding on Cross jellyfish
    Image by Alexander Semenov
    And in the tropical Indo-Pacific (Lembeh, Indonesia), Astropyga radiata is feeding on some nice dead fish (and who doesn't like a nice dead fish every so often?)
    Radial Sea Urchin feeding on dead fish - Lembeh
    Image by Christian Loader
    Up until recently though, feeding in sea urchins has been thought to be relatively passive and opportunistic.  Whatever comes along is good to go!

    Most people don't think of sea urchins as aggressively chasing down and pursuing ACTIVE prey...
    This notion was recently shown to be incorrect...

    3. Predation
    Probably one of the most dramatic deep-sea/paleontology events in the last few years was the discovery that, not only could stalked crinoids (echinoderms with a ring of feeding tentacles and a stalk) crawl BUT they did so with some urgency!


    It turns out that they were running from Cidaroid SEA URCHINS. I've written up these papers here.
    Calocidaris -a cidaroid urchin. Image by D. Pawson
    This predatory act was observed on video between shallow water species. Here is a shallow water cidaroid urchin attacking a feather star...

    WARNING! Those who do not wish to watch crinoids being brutalized and devoured should avert their eyes!


    Further evidence on deep-sea crinoid skeletal pieces is here. That notch is a scar left over from where an Aristotle's Lantern has gotten to this animal...
    Urchin bite on a crinoid stem by T. Baumiller
    There have also been recent accounts that leaving sea urchins in large numbers under artificial circumstances (sea urchin farms) leads to cannibalism! (here)  Sea Urchins eating OTHER Sea Urchins!!

    2. Deposit Feeding/Sediment Feeding
    Whew! That was quite a violent section for sea urchins, wasn't it???  Let's go to something a bit more majestic!

    One of the NEATEST stories in sea urchin evolution is how a major sub group, the "irregularia" aka the sand dollars, sea biscuits, and spatangoid  ('heart urchins') sea urchins all evolved from a more open lifestyle with the feeding modes shown above (herbivory, predation, omnivory) to a specialized series of body forms that involve plowing through sediment/mud/sand in order to obtain food. Deposit or sediment feeding. A more involved post of this story can be found in this post.

    Feeding in these animals is intrinsically connected with their life mode and body shape. Here are some videos that show some of these animals plowing through sand...sometimes just to get around but maybe also to feed?

    Japanese sand dollar plowing through sand...but check out the food going to the mouth at 1:05
    .


    Note all the spines moving through the sediment...


    Again.. check out the spines!


    1. Filter/Suspension Feeding
    So, now that I just got done telling you that sand dollars and their relatives are deposit feeders.. I will immediately point out the exception!  Perhaps the most UNUSUAL feeding mode in sea urchins is filter feeding, i.e., obtaining food from water currents using some kind of sieve or screen.

    Urchin morphology tends to be...counterproductive where this sort of feeding is concerned.. Except in TWO unusual examples.....

    Dendraster excentricus-is the so-called "Eccentric Sand Dollar"which lives along the west coast of North America.  So named for the very erratic pattern of its feeding grooves on the oral surface.
    sand dollar bed
    Image by fiveinchpixie
    sand dollars (dendraster excentricus)
    Image by Peter_r
    Note an oddity in its feeding posture.. these animals are tilted at an angle into the water current standing on its "side" in the sand. Other sand dollars such as the ones listed under #3 lie flat on the sandy bottom.

    Dendraster uses its tube feet, pedicellariae and spines to pass along food caught from the water currents to the mouth.. More info on this species to be found here..  This is a pretty commonly encountered animal, but really when you look at them in this fashion, they are freaky deaky! 

    Dermechinus horridus  So yes. Saved the BEST for last! 

    Dermechinus horridus is a strange deep-sea sea urchin which has a body, literally shaped like a cactus, with sharp, needle-like spines to boot!  It is among the oddest of the sea urchins known.
    Image by NIWA
    But what's even more strange? Its been postulated that this species captures food from the water!! In other words...a suspension feeder! (I wrote this up here)


    Here is some of the FIRST available video of this species in its natural habitat occurring next to brisingids, which are suspension feeding asteroids...


    And although I don't wish to steal his thunder, let's just say that info from a recent International Echinoderm Conference presents some intriguing possibilities!
    Image by NIWA
    Spiny balls! Predators! Diggers! Eaters of Kelp and Purveyors of fine watery nutriton! Huzzah!



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    Purple Urchins
    Image by Annie Crawley
    Sea urchins are among the best known, most heavily published on, and most "important" of echinoderms. People eat them and they are studied in marine ecology pretty heavily. Most marine biologists I know think highly of sea urchins. They're pleasant animals with an unusual appearance

    But the truth is, no matter how adorable or fuzzy, useful and/or cute an animal may be, TOO many of them is nothing but trouble! True for Star Trek tribbles and for sea urchins!
    (disclaimer: Tribbles are science fiction, sea urchins are not)

    *Tribble factoid: Someone has ACTUALLY given tribbles a scientific name: Polygeminus grex! don't believe me? go see Memory Alpha!)

    Tribbles are actually a GREAT introduction for today's topic: SEA URCHIN BARRENS!

    What are Sea Urchin Barrens??  These are places where a sea urchin species' abundance increases dramatically to the point where the urchin devours EVERYTHING in its path, effectively leaving all else 'barren' except for more hungry sea urchins.
    Purple Urchins
    Image by Annie Crawley
    DSC_001720091004
    DSC_003020091004
    Images above by AndyOlsson
    This is not far removed from the imagined "ecology" of Star Trek's tribbles (A good essay applying real population math about tribble populations can be found here, but this image from the famous ST:TOS episode hopefully gives you the general idea!)
    Image from TrekNews.net
    The gist of it is simple:  TOO MANY URCHINS and they EAT TOO MUCH. But unlike tribbles (which were eradicated by Klingons-yes I know they're not real), in the case of sea urchins, we can actively study the ecological interactions and conditions which have caused the populations to explode in number.
    DSC_001720091004
    Image by AndyOlsson
    Here is a video showing tons and tons of Red Urchins (S. franciscanus) on a barren in Southern California. Thee bottom is essentially devoid of all but more hungry urchins!



    What causes urchin barrens? 
    Um. Its complicated but the common thread seems to be that there is an association between barrens and the absence of sea urchin predators.

    In many of the papers I've read about Northern Hemisphere species, the loss of a major sea urchin predator seems to be one of the immediate attributed causes of the runaway population growth, but as we've seen with other species such as the Crown of Thorns (Acanthaster planci) the story is often complicated....

    Most of the studies involve temperate-cold water urchins in the Strongylocentrotidae, specifically Strongylocentrotus purpuratus (purple urchin), S. franciscanus (red urchin), S. droebachiensis (green urchin) and S. polyacanthus.  Literature was abundant, but this paper by Nathan Stewart & Brenda Konar provided much of (but not all) the info for this post.

    In one of the most familiar studies from the Pacific Northwest coast, the main predators were sea otters (in many cases, I assume Enhydra lutris-some papers did not mention species).

    The fundamental ideas outline the notion that as sea otter populations decline, predation pressure decreases and with nothing to keep the populations at a controlled level sea urchin populations dramatically increase and began to devour kelp (and really everything else!)  to the extent that they effectively clear the bottom.
    Urchin Barren
    Image by Santa Monica Bay Restoration Foundation
    Purple Urchins
    Image by Annie Crawley
    In Stewart & Konar's paper, individuals from these population explosion urchins were compared against "healthy" urchins which occurred naturally in kelp forest habitats.  Some dynamics:
    • Urchin densities were SEVEN times greater than those elsewhere
    • Kelp forest (vs. 'barren') urchins were larger and more robust
    • "Barren' urchins were smaller with less tissue
    • "Barren urchins had little to no reproductive tissue compared to kelp forest urchins
    Different species of Strongylocentrotus (as well as other urchin species!) live in different places and have different predators!

    On the North Atlantic coast, there is a similar population explosion of the Green Urchin, Strongylocentrotus droebachiensis, which from the look of it, is pretty severe

    Here's a video that shows just WOW... a lot of them..

    I have briefly written about the impact of this many Green Sea Urchins. They all POOP! This actually has a pretty serious ecological impact. 

    Some, such as this paper, have proposed that these population increases have been caused by the loss of lobsters (Homarus americanus) which feed on green sea urchins. But in all liklihood, as the system is better understood the more complicated the explanation.
    Northern Lobster, Gulf of Maine
    Image by AJmart
    Other predators, such as wolf eels and starfish, also feed on green sea urchins and well.. it can get messier...

    Now, in the Southern Hemisphere we have a similar, parallel situation with a completely different family and species of sea urchin: Centrostephanus rodgersii (Diadematidae).
    Sea Life: Long Spined Sea Urchin
    Image byEdward Vella
    Climate Change Enters the Picture! 
    A paper by Ling et al. 2009, in the distinguished Proceedings of the National Academy details  a scenario with some important dynamics
    1. The range of the urchin is dramatically expanded because of increasingly warm waters in/around the eastern Tasmanian region.
    2. The lobster Jasus edwardsii is one of the primary predators of Centrostephanus and has been heavily overfished. The BIG lobsters that would feed on urchins are taken for food leaving the urchins to run amok!
    Its important to note how significant the human factor has played into these dynamics. Climate change and overfishing are thought to be the primary agents responsible for urchin "barrens" in these circumstances.

    This issue has been conveniently summarized in this video...


    The takeaway lesson: Predator loss seems pretty strongly associated with urchin "barrens" aka population explosions. But all sorts of environmental factors, including warmer waters, and multiple predator interactions can be important..

    So we have a LOT of sea urchins. Couldn't we uh..just eat them? 

    Yes. 

    BUT, you can after all, only fish so much. After you've taken the lobsters, the urchins and the kelp what else have you got left? A good answer seems to lie with good sustainable fisheries management..but we shall see how this works out...

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    thanks to MBARI!
    People are always fascinated by how animals eat and, I think, the weirder the better. Starfish have one of the most distinctive feeding modes of all animals and I think, that's why people get fixated on how they consume their prey.

    The feeding posts on the Echinoblog are among the top ten highest hit and the research literature is full of comprehensive studies detailing the feeding ecology and behavior of a great many starfish species. 

    As one might expect, the great majority of feeding studies were initially those of shallow-water species which were easy to observe. Feeding is important to understanding marine ecology in many systems. So, its not just some casual trivia that comes in handy at cocktail parties.

    But what about deep-sea species? Understanding the role of predators in these often inaccessible systems is important.  In cases, such as with deep-sea coral, its important to understand what role these animals play, especially given how little we know about the individual animal's importance.

    How does one figure out the role..and indeed, the importance of these species in such far away and forboding habitats??



    1. The Starfish
    Fig. 1 from Gale et al. 2013
    Ms. Gale's research focused on seven deep-sea starfish species from the North Atlantic:
    A. Ceramaster granularis
    B. Ctenodiscus crispatus-aka the mud star (learn more about it here)
    C. Hippasteria phrygiana (learn more about it here)
    D. Leptychaster arcticus
    E. Mediaster bairdi
    F. Novodinia americana-a brisingid
    G. Zoroaster fulgens (more about Zoroaster here)

    but also had some feeding notes on this weird guy.. Tremaster mirabilis! (about which very little is known)

    Most of these species occur in a primary range of about 500 to 1500 meters, but some can get relatively shallow. Most are difficult to study and live on the deep-dark sea bottoms...

    2. Figuring out feeding
    There's generally TWO ways to study feeding:
    • Directly: i.e., you watch a species consuming its prey (or whatever food) and voila! You have a direct feeding observation.
    • Indirectly: You have something which provides inference about what the animal has already consumed. Look at the gut contents or something similar...
    In the old, old days, figuring out the feeding ecology of deep-sea species was difficult. Specimens were collected via net-and usually brought up badly damaged. The animals were mostly dead and had often emptied all of their gut and stomach contents. Rarely did you have an opportunity to see the animal interacting with any possible prey items. Any interactions you might have spied could have been caused by the trawl net scooping up any and all of the bottom fauna...

    In contrast, I think Ms. Gale et al's paper has acquired some great information using some modern techniques and good ol' fashioned detective work!

    Direct Observation  So, the most obvious and direct way to observe feeding is by watching it!  These days, submersible robots aka ROV's (Remotely Operated Vehicles) are one of the main platforms for these types of observations. I've done some similar work in the Pacific (here)
    Fig 9A from Gale et al. 2013
    This is Hippasteria phrygiana, a widely occurring cold-water/deep-sea coral (and cnidarian) predator, but Gale et al. observed several other species from the deeps, about 500-1100 meter depths,  of the North Atlantic.

    Several species were observed as predators for the first time, whereas others were confirmed. For example, Novodinia is a brisingid with a documented suspension-feeding mode and we saw more of that in Gale et al. 2013.

    Gale et al. also reported feeding for Tremaster for the first time! Feeding on coral...
    Tremaster mirabilis

    Laboratory Feeding Experiments
    As a complement to the direct observations, Gale also performed several laboratory feeding experiments and was able to observe several direct feeding moments!

    Predictably, Hippasteria fed on various cnidarians, including sea pens and other deep-sea cnidarians.
    Whereas Ceramaster fed on sponges..

    But not all the prey allow the predators to just...eat them. Some, like the sea anemone Hormathia
    nodosa 
    Image from Natioal Museum of Northern Ireland via EOL
    and the deep-sea coral Flabellum alabastrum 
    Image from Fisheries & Oceans Canada via marinespecies.org
    used their tentacles (which all have stinging cells) as a defense against the oncoming hunger dogs!  And this was effective against the more timid Ceramaster but not against Hippasteria. Flabellum was fed upon by Hippasteria VERY quickly (in 18 minutes)..

    Indirect Evidence. This is where some newer techniques shows us some cool ecological stuff!!

    Stable Isotopes!!
    Here is a video that explains the basics of stable isotopes but basically what it comes down to is this: elements like nitrogen (N) and carbon (C) undergo changes as they pass through different ecological levels in the environment.

    In doing so, they become kind of like a "fingerprint" for a particular kind of ecological role. So, for example, species with a stable isotope N (Nitrogen) value of about 16, but w/ Carbon value of about -14 (Hippasteria, Ceramaster and Mediaster) are higher within the overall trophic relationship among these asteroid species.
    Fig. 6 from Gale et al. 2013
    You've seen Hippasteria, but here's Ceramaster granularis
    Ceramaster granularis, Sjøkjeks
    Image by EIN _LEIK
    and Mediaster bairdi
    Mediaster bairdi
    Image by K. Gale

    All the other species, including Novodinia americana, Leptychaster arcticus, Ctenodiscus crispatus and Zoroaster fulgens display lower values which would be consistent with their previously thought of feeding modes as suspension feeder (the brisingid) and deposit feeders/detritivores (mud stars, including Leptychaster and Ctenodiscus) and Zoroaster.

    Gut Contents & Prey Items!
    One other indirect way of looking at food items?  Gut contents.  What were they eating?

    Ms. Gale did a LOT of work looking through the guts of many starfishes.. Much of how they fed is based on detective work.  For example, many animals such as deep sea gorgonians and such, after being digested leave only skeletal bits called sclerites.

    Fortunately, these can be used to identify the animals with some accuracy. Curiously Hippasteira also had some crustaceans in its gut..
    Figure 3 from Gale et al.
    One of the subject animals, Zoroaster fulgens has been one of the more mysterious deep-sea starfish species in my experience is an infaunal predator, that is, a species which eats animals living in bottom mud and sediments.  A related zoroasterid called Doraster is shown here with a snail in its mouth with snail food in the red circle

    Gale et al reiterate the importance of the feeding ecology of many of these species...
    • Hippasteria is a widely occuring asteroid which likely affects coral populations
    • Ctenodiscus-the mud stars occur in LARGE numbers, up to ~6000 individuals per hectare and influence the sediment as they move around through it feeding on mud..
    Fr. Arcodiv.org
    • Suspension feeding asteroids such as Novodinia capture food from the water column that would ordinarily not be made available to bottom feeders
    Brisingid Seastar
    not N. americana. Image by NOAA National Ocean service
    I've recently discussed some recent observations of a seemingly innocuous species, Porania pulvillus as a predator rather than a passive ciliary feeder. Understanding deep-sea ecosystems is an exciting endeavor, who knows what we'll find!  Simple things like feeding are intriguing and interesting-but poorly known. What will the important impacts of these species be down the line?

    But even BASIC knowledge such as this is a complex and time-intensive process. It starts with work like this...

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    Sea Shell
    Image by gary.brake
    The Scanning Electron Microscope (SEM) is a wonderous device. Simply put, electron beams provide a highly detailed almost surreal image of the surface they are directed at.

    But what happens we direct an SEM at animals that are ALREADY kind of weird? The striking beauty of sea urchins is revelaed!

    The sea urchin skeleton. Also known as a TEST.  One of my many regularly repeated caveats- these are NOT shells. These are underlying skeletons which have a layer of skin which is typically removed to reveal the more aesthetic skeleton...

    Here is an example from a cidaroid sea urchin.. Those round knobs or bosses?  Those are where the spines articulate with the body...
    Cidaris 1
    Image by Gripspix
    Here's a nice macro shot of aforementioned "boss" (=the knob which connects with the spine).
    test photos
    Image by "Nervous System"
    But what happens when we focus a Scanning Electron Microscope (SEM) on these surfaces?  (note that these images are a different species from the one above).
    sea urchin
    Image by Monkey.grip
    Here's another view looking down. Note how the skeleton is actually porous! Echinoderm skeletons aren't simply inorganic calcium carbonate, they are actually infused with tissue...
    Sea Shell
    Image by gary.brake
    sea urchin
    Image by Studio Jonas Coersmeier
    Another view from a different perspective...
    Shell-7
    Image by particlesixtyfour
    sea urchin landscape
    Image by monkey.grip
    Closer...
    Shell-2
    Image by particlesixtyfour
    ..and closer still!
    Shell-4
    Image by particlesixtyfour
    right on top of it!
    Shell-18
    Image by particlesixtyfour
    Here's one that shows not only the spine "bosses" but also the sieve plate aka the MADREPORITE on a sea urchin. See that really porous plate (the one with all the black dots) in the right hand corner??

    Untitled
    Image by Studio Jonas Coersmeier
    But wait! What about the SPINES???   I'm not sure which species these are from.. but they give you a good idea about the fine topology that one might not realize is present from simply looking at a spine with your eye... 
    Spike-1
    Image by particlesixtyfour
    Closer! 
    Spike-2
    Image by particlesixtyfour
    And finally... CLOSEST!!
    Spike-3
    Image by particlesixtyfour
    And just to cap off the whole odyssey through a sea urchin spine... here is a cross section THROUGH a spine magnified 150X!!!   The final three images below are from the Biology Dept. at the University of Dayton! 
    Here are the featured spines...
     and together to show perspective...


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    So this week was one of the biggest Marine Biology Events EVER! It was on TV almost ALL DAY (and for the next several days) and involves some of the Earth's most mysterious and unusual animals!

    I am of course talking about the 2nd leg of NOAA Okeanos Explorer Northeast US Canyons Expedition 2013!!!  (disclaimer: I am not an employee of NOAA)
    Quick Summary: NOAA has a research vessel which travels the world deploying a robot (Remotely Operated Vehicle or ROV) equipped with many HD cameras and a huge ability to record images from the deep-sea.

    The Okeanos Explorer has been to Indonesia and many other locales, such as the Galapagos and the deeps off the Caymans, but is currently operating off the east coast of North America, surveying and studying a series of deep-sea canyons and seamounts as seen here.  Those on the legs I've seen (2nd leg?) are in white arrows...
    Original Image for this map here
    Here is their telemetry which gives you an idea of where they've gone. Some of their dives are VERY deep, down to nearly 3300 meters!!

    The Okeanos Explorer is the mothership for the robot (the ROV) which is tethered to the ship as such.. there is an accessory ROV which aids in navigation and so forth...

    All of these operations are monitored from a neat control center back on the mother ship...

    The AWESOME thing about the OE program is that the HD video from the ROV via the ship can be BROADCAST LIVE OVER THE INTERNET!! 

    And so for the last week we have been listening to the awesome narration of two experienced deep-sea scientists: Dr. Martha Nizinski, a deep-sea crustacean specialist at the National Systematics lab in Washington DC and Dr. Amanda Demopoulos, a research ecolgoist/ geologist for the United States Geological Survey
    Those who have tuned into the LIVE REALTIME video broadcast have been able to watch "over the shoulder of scientists" as NEW deep-sea habitats are explored!!

    What's even more fantastic? Many deep-sea biologists, some world experts in the field, are actually listening in via phone, or via internet forums. I'm one of the world's experts on starfish and I'm monitoring via Twitter (@echinoblog) and via conference call.

    Each day of the expedition can go anywhere from 5 to 7 hours. So there's a LOT of footage. So here.. I present some of the highlights of new discoveries and neat, weird deep-sea animals from the last few days of video footage.

    There's still more to come and undoubtedly, I've undoubtedly missed some but this gives you a nice overview of new discoveries and awesome stuff from the 1000+ meter deeps off the east coast of North America!

    My thanks to Dr. ChrisKellogg (@drchriskellogg) whose "Screen Grab Fu" was FAR superior to mine!

    A NEW cold seep community in Nygren Canyon!
    A cold seep is a place where toxic materials, such as sulfides, hydrocarbons or methane leech out the bottom and into the water (see here for more info). Animals and other organisms take on special adaptations, such as the ability to absorb and process these toxic materials, so that they can live there in a similar fashion to the way special worms and clams live in hydrothermal vents habitats.

    These animals are heavily studied and are important to ecologists as well as physiologists and even scientists researching astrobiology (those that explore how life on other planets originated in extreme habitats)

    Cold Seep habitats are unusual and when found, they are often monitored by the scientific community for study because of their potential importance.

    This Stalked Crinoid with weird projectons
    Stalked crinoids are an older form of crinoids and resemble animals seen in the fossil record (here for some examples)

    and certainly the OE expedition saw its share..
    What was weird about this one?  look closely...
    The stalk is COVERED by tiny little protrusions!!
     
    Parasites? Commensals Part of the animal?  A new species?  MANY questions! 
    Sea Spiders aka Pycnogonids crawl on deep-sea corals and other cnidarins
    Here's one on a sea pen
    Another crawling on some deep-sea coral


    Weird & Rarely Seen Deep-sea starfish species!
    This starfish, called Pythonaster, is known from fewer than 6 specimens in the entire world. This is the 2nd time this animal has been observed alive and the FIRST time it has been observed alive in the Atlantic. 
    Here is a plate of this animal from the HMS Challenger Expedition, which described it in 1889!! 
    This starfish, Neomorphaster, is better known to scientists, but seeing it alive like this? That's not something that happens often.
    This looks to me like the starfish Hymenaster, a member of the Pterasteridae, aka the "Slime Stars" which you can go here to read more about!  See that little center hole on top? That's called the osculum. and that's where the slime comes out! It opens and closes to allow water in and out.

    Starfish Eat a LOT of stuff
    I've written about deep-sea coral eating starfish before (go here). I've described more than a few species of deep-sea predators. Here's Evoplosoma hanging on and probably feeding on whatever that grey stuff is (probably some octocoral)

    Is this why so many Neomorphaster are missing two arms???? 


    Brittle Stars Live on EVERYTHING
    They live on other echinoderms-such as this stalked crinoid
    This deep-sea octocoral...



    Other animals we saw a lot of....
    Barnacles! Deep-sea barnacles are thought to be old relative to their shallow relatives..

    Glass Sponges!  aka the Hexactinellida.  These are literally animals made of glass fibers. Their bodies take on really remarkable shapes. There were a lot of these. Especially on Mytilus Seamount. 

    This one floats on a long stalk!

    whew! Anyway this doesn't scratch the surface of ALL the weird and wonderful things that were seen during the expedition. 

    Go HERE to see the Expedition log 

    Daily Expedition Updates are HERE.

    What more amazing creatures and ecologies will they discover?? 

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    A very local speciality.
    Image by Nuytsia@Tas
    Data for this post was derived from Maria Byrne's 1996 paper in Marine Biology: "Viviparity and intragonadal cannibalism in the diminutive sea stars Patiriella vivipara and P. parvivipara (family Asterinidae) vol. 125: 551-567 which is a pretty neat piece of work that set the groundwork for their paper in Biology Letters which was just published today! Today's post has been reported in the news (here.

    Our story begins with an overview of two unusual and quite tiny starfish! Some details:

    • Occur in Tasmania (Southern Australia) 
    • Two species, Parvulastra vivipara and P. parvivipara occur on rocks and surrounding areas.
    • One of those starfish, P. parvivipara is among the world's smallest adult sea stars. 

    Indeed! Look how cute and tiny they are!
    Tiny endemic.
    Image by Nuytsia@Tas
    But the  truth is that these tiny little starfish have all kinds of shocking sex secrets!

    1. Both Species of Parvulastra are self-fertilizing hermaphrodites. 
    I have written about similar species in the same genus (Parvulastra) here. 
    Yes, that's pretty much self explanatory. Individuals are simultaneously both male and female AND if need be they can fertilize themselves. 

    They typically have between 6 to 8 female gonads and 1 predominantly male gonad. However the amount of sperm present would not be expected in those species which are exclusively self-fertilizers-so SOME outcrossing (ie sex with other individuals) does occur.
    Patiriella vivipara
    Image by Nuytsia@Tas

    2. Parvulastra broods juvenile starfish in a brood chamber (aka "live birth" aka viviparity)
    Several species of starfish are known to possess "brooding" behavior (I've written about them here). That, is the adult "carries" either internally or externally several tiny juvenile starfish with it until they are ready to move off on their own as full adults.

    Each adult Parvulastra carried multiple juveniles across a range of sizes. Here was one example of a clutch containing 30 individuals from ONE large individual. Number varies with size..
    scale bar= 1.0 mm, From Byrne 1996, Fig. 4e
    These further images from Byrne's paper give you an idea of where they are located. Essentially throughout the body cavity between gonads. This differs from other species which can have them living around the mouth or in other locations.
    From Byrne 1996, Fig. 4a
    So, eventually, those little baby starfishes have to leave the comfort of the mother's body cavity. This happens when they reach about 25-30% of the parent's body diameter.

    The downside of having brooded juveniles is that they tend not to go very far from the adult. In other species, the larvae would be dispersed over wide distances but here, they are retained or crawl away, staying near the parent.. 

    Eventually, they exit via openings in the abactinal body wall called GONOPORES. 

    But what motivates the exit? 

    3. Those juvenile starfish are cannibals! (aka intragonadal cannibalism)
    Life is harsh and these starfish know it better than anyone. The gonads in these animals are pretty small which implies that food for the juveniles isn't really enough to keep them sustained on their own..

    So, as soon as the brooded juveniles develop a mouth they begin feeding on their siblings in the body cavity! In the specimens examined several of the larger brood individuals, which contained traces of the smaller ones in their gut contents in addition to other observations..

    Several possible reasons may motivate the departure of the smaller juveniles from the brood space. Temperature or any number of factors.

    Byrne speculated on one reason that juveniles may vacate in order to avoid being fed upon by their larger siblings.. Here is a cartoon supplied by the Echinoblog Art Dept. which illustrates this notion (which to be honest was mentioned as only one sentence by Byrne in her paper).
    Thus starfish join the illustrious ranks of those animals which have active, intrachamber type young which feed on one another including sharks, fishes and salamanders and insects-although there's a bunch more..

    4. Exit to the Outside World! 
    Ultimately, then we see various brooded juveniles vacating the brood space via the gonopores (which flex and open) with the tiny juveniles emerging on the surface and eventually moving away...
    Fr. Byrne 1996, Fig. 8b
    Thanks to the intragonadal cannibalism however, sometimes you get a REALLY big one which continues to grow INSIDE the parent.  Ultimately reaching a size at which it cannot physically escape on its own..  

    Yikes! Talk about living in your parent's basement! 
    From Byrne 1996, Fig. 4h
    5. Reproductive Impact on Populations
    As indicated above, a recent paper by Carson Keever and others has found some significant drawbacks that this unusual reproductive behavior will have on populations of Parvulastra.
    • Self-fertilization by hermaphroditic adults and brooding behavior causes strong inbreeding and "genetic poverty"
    • There was nearly a complete loss of genetic diversity among all populations of Parvulastra and given the very restricted geographic range of these species+ the very limited way they can disperse their juveniles across wide distances there's little potential for populations to expand.
    • Thus, these live-brooding species with little to no gene flow display a high risk of extinction
    So, there is serious concern about these species to withstand any kind of temperature or climate shift. The populations of these live-bearing starfish species is pretty small and pretty restricted. Potentially any kind of abrupt habitat change could wipe out these starfish with these unusual life modes..

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    Tylocidaris clavigera from the Cretaceous of England Stunning image from the BMNH Echinoid Page. here
    SEA URCHINS! Everyone kinda knows the basic idea: round spiny ball that lives in the ocean but most folks aren't as familiar with how CRAZY the spines can get. ESPECIALLY in the fossil record!

    Most of these taxa are either cidaroid sea urchins or closely related to them. Cidaroids are considered a "stem group" among sea urchins. That is to say, they arise early in the evolutionary history of the group. They have a different jaw apparatus and vary in several other respects. Including the unusual absence of an epidermis from the spines, which permits growth of various other organisms on the surface. I've written about this here.  

    Cidaroids may also be very important in understanding deep-sea dynamics and the historical ecology of other echinoderms, such as crinoids (feather stars). See that article here.  They have been around for quite awhile.. and have been known since the Paleozoic..

    But some of the CRAZIEST urchins occur from the Mesozoic, that is during the time best known for the dinosaurs. Oceans were widespread during this time

    One of these neat urchins is the Mesozoic (Jurassic to the Cretaceous) to recent cidaroid urchin, Tylocidaris.

    Tylocidaris appears to have MASSIVE, club-shaped spines which were presumably used for defense..
    Sea Urchin (cast)
    Image of a cast by Ryan Somma
    Here is some bewildering diversity of Tylocidaris spines, which all look like maces or big notched watermelons!  Presumably these were used as defense against predators.

    MUCH thanks for the images from this Danish gentleman's excellent page about fossil sea urchins! 

    These spines are from a Cretaceous Tylocidaris sp.
    Image by Søren Bo Andersen fr. his website
    More Tylocidaris spines!
    Image by Søren Bo Andersen fr. his website
     ..and still more!
    Image by Søren Bo Andersen fr. his website
    Interestingly, the British Museum's sea urchin website also indicates that a LIVING member of this family is still kicking around.. the unusual Psychocidaris!
    Psychocidaris oshimai..

    Curiously, the spines seem to be made up primarily of this weird cortex like covering...
    Here's a video from a mineral/fossil show showing a bunch of fossil Tylocidaris-like urchins to a jazzy tune!


    SIMILAR URCHINS...
    the Jurassic Pseudocidaris mamossa Big CLUB like spines!
    www.fossilplanet.com,pseudocidaris mamossa,erizo fosil,fossil echinoid,jurassic,kimmeridgian,mesozoic ,fossilplanet
    Image by Fernando Bravo
    Gymnocidaris kochlini  (from Morocco)
    Gymnocidaris kochlini
    Image by USAgeology
    Asterocidaris mendrina  From Morocco (urchin is 3.7 inches across)
    Asterocidaris mendrina
    Image by usageology
    And just in case you thought only fossil urchins could have all the fun! here' an assortment of neat urchins that are alive TODAY which bear bizarrely shaped spines...

    But note that the spines aren't just huge and club-like.. they have all of this weird ornamentaton. What could their function be? defense? assist in reproduction somehow?

    Goniocidaris sp. from the South Pacific. (MNHN Paris collection)

    A second Goniocidaris species.. with very different spine patterns..

    Morphology-seemingly simple and straightforward... and yet, what do the animals use them for?

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    Coelopleurus exquisitus Coppard & Schultz, 2006
    There is a natural and wonderful symmetry to many natural objects and echinoderms have always had a certain appeal to folks with artistic natures. Their skeletons are pentameral and often have no shortage of patterns and visually interesting processes. Go here to seem my SEM odyssey of the urchin test!

    Sea urchins are no exception to this-and everyone I know who has ever found an intact sea urchin (or sand dollar) test on the beach is always delighted. A "test" is the name of a sea urchin skeleton. They don't have "shells".

    Here's a nice example of a cidaroid sea urchin test. The spines attach to the "knobs" (called bosses) that are present on its surface.
    Sea Urchin Shell
    sea urchin test by Rainy City
    Today, I thought I would present some of the many delightful examples that many of these tests have found their way into the creative processes of the wonderful artists on the Internet!  Then compare below with some examples of sea urchin tests with their own innate artful patterns!

    Cidaroid Urchins a la Warhol! by Calypso985
    Urchins a la Warhol
    A stunning underlit cidaroid urchin test by Mark Bolles
    Pencil Urchin Shell on White Plexi
    A neat repeating Urchin Spiral by Jeff Kreulan 
    Urchin Spiral
    "Red Tide" part of an art exhibit featuring urchins with a distinctive presentation. Pic by Selene Vomer
    red tide
    "Algae Bloom"  Image also by Selene Vomer. Chicken skeleton over urchin skeleton. Hm?
    algae bloom
    "Phosphorflock" Pic by Selene Vomer. I think its supposed to represent some kind of egg?
    phosphorflock

    Here it is illuminated...
    the sea urchin up close
    Image by tiboutoo

    Illuminating or highlighting urchin tests with lights, lasers, fluorescence is a common theme...

    An illuminated urchin by gmenut
    Urchin

    One lit up with fluorescent lighting... "Voodoo Moon" by Sea Moon
    Voodoo Urchin...

    "Sea Urchin Laser Fluorescence" by Bob Fosbury
    Sea Urchin laser fluorescence


    And there's this stop motion classic "Javelin" by Ian McAlpin


    Natural Beauty  In contrast, here's some tests in their natural glory...

    a cidaroid test by gripspix1
    Cidaris 1


    Another urchin test. Image by "fontplaydotcom"
    shell 6


    The test of Coelopleurus exquisitus, a recently discovered New Caledonian sea urchin species, described by my colleague Simon Coppard, who found tests of this species on Ebay a few years ago!

    Amazingly, the patterns? ARE NATURALLY OCCURRING. Those are on the test under the spines and all of the other structures and skin on the surface! They don't disappear after the animal has died. They are ingrained in the mineral structure of the test.

    Both images below are by Simon Coppard
    Coelopleurus exquisitus Coppard & Schultz, 2006
    Coelopleurus exquisitus Coppard & Schultz, 2006


    and we didn't even get started on Irregular urchins like Clypeaster and the other Sand Dollars..
    Sea urchin



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    <i>Pycnopodia</i> detail

    Today is a "report from the field" by Jonathan Martin, a research associate at Simon Fraser University, who is among other things, an ROV pilot, diver and photographer. His pictures can be found at this Flickr stream here.

    Martin has recently sent me a series of images and video that show a massive die off of the sunflower
    star, Pycnopodia helianthoides in the waters of British Columbia in 20-50 feet of water.

    A picture of the sunflower star in a healthy state is above. Pycnopodia is a prominent member of the Pacific northwest intertidal/subtidal marine fauna. It boasts about 20-25 rays and can get to be quite large (about 2 to 2.5 feet across).

    A couple of years ago I wrote about a huge Pycnopodia population explosion in British Columbia waters.

    ALL pictures in today's post were provided by Jonathan (except where noted otherwise).

    The Evidence: Images & Video

    Here's a video transect made by Jonathan


    See all that white stuff on the bottom?? Those are decaying, white tissues and ossicles from sunflower stars. You can see the fleshy remains all around the bottoms.

    His direct observations (dated August/September 2013):
    I just got back from a dive out in West Vancouver though, and there seems to be a huge mortality event of some kind with the animals, where they seem to waste away, 'deflate' a little, and then just... disintegrate. The arms just detach, and the central disc falls apart. It seems to happen rapidly, and not just dead animals undergoing decomposition, as I observed single arms clinging to the rock faces, tube feet still moving, with the skin split, gills flapping in the current. I've seen single animals in the past looking like this, and the first dive this morning I  thought it might be crabbers chopping them up and tossing them off the rocks. Then we did our second dive in an area closed to fishing, and in absolutely amazing numbers. The bottom from about 20 to 50 feet was absolutely littered with arms, oral discs, tube feet, gonads and gills, the the extent where it was kind of creepy.
    More pictures of Pycnopodia in various states of decay..
    P1050297
    P1050330

    P1050364
    Partial remains of a disk and white, dead starfish tissues..

    P1050366


    In some cases, arms were separated with tube feet still moving around
    P1050317P1050363

    What makes this such a concern?  OTHER starfish species in completely different lineages also seem to be affected. The sea star predator, Solaster dawsoni was also observed in various states of distress..

    Solaster feeds on other starfish and does feed on Pycnopodia, so is there a connection??  Especially with the recent population explosion??
    P1050360


    P1050344


    P1050397


    P1050395


    So What's Going On? 
    So, there were a number of different ideas that buzzed through my head. Again, this is all SPECULATION on my part...

    1. Is this related to the population explosion, observed almost 3 years ago??  Could the huge populations from 2010 be suddenly dying off? Famine? Disease? (see below) This would be an unusual (or at least poorly known) phenomena. I've seen Pycnopodia in aquaria  live out long lives, so I don't think this is some kind of "natural causes" thing...

    2. Could this be a disease?  Jonathan has mentioned the ciliate (Protist) parasite which inhabits sea stars in the Pacific Northwest. The ciliate effectively castrates the host, but has never been observed to actually cause much more damage than that. And accounts of the ciliate suggest that it occurs in a very small % of the overall population.

    There are accounts of many sea urchins being decimated by various bacterial infections, such as Bald Sea Urchin disease but my skim of the literature suggests that there isn't anything known about similar diseases in sea stars.  Most mass-mortalities of seastars have been associated with environmental changes- freshwater from rains, storm and wind, toxicity in the water from geological events and so on...

    Could this be related to what has been observed on the East coast with Asterias See also this report.Where populations of the well-known intertidal starfish (and btw, SAME family as Pycnopodia) have been undergoing population declines for unknown reasons.
    Purple Starfish
    Image by lifeboy252
    3. Why is it affecting other species? So we have one big Pycnopodia die-off. Why have all the Solaster stars ALSO been dying?  One immediate answer might be that whatever toxic substance is in Pycnopodia has been fed upon by Solaster, resulting in further mortality. Or it could be in the water.. More data and observations are needed.

    Have other species in completely different ecological regimes died? 

    SO FAR, this has been observed only in the British Columbia region. Hopefully, this is just an isolated incident and nothing that will be slowly moving in any other direction. 

    I'm not an ecologist or an invertebrate pathologist.. so maybe someone out there with an appropriately equipped lab will embrace this and seek out the answers?  and hopefully whatever it is, won't be much more widespread.. 


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  • 09/10/13--22:51: Starfish Wasting Disease!

  • Last week I reported on an unusually large die-off of the North Pacific sunflower star, Pycnopodia helianthoides (among other starfish species) in the waters of British Columbia. The story even got picked up by National Geographic!
    P1050360

    This sparked some good academic discussion here which I can only hope will lead to some further insight into what is happening.  One useful thing which came up was the mention of something that would be a good follow up to last weeks' report:  Starfish Wasting Disease!

    I have spoken of ciliate protist parasites in sea stars before but this is something different.

    Details of the post today about Starfish wasting disease is based on this paper in the journal, Diseases of Aquatic Organisms from an article by Amanda Bates, Brett Hilton and Christopher Harley in 2009

    Other information is from an account of starfish wasting disease in the Channel Islands by Ginny Eckert and colleagues. This paper is freely available here.

    I should also mention that my friend and colleague Dr. Allison Gong has documented an outbreak of wasting disease in her water table at UC Santa Cruz. I've borrowed many of her pictures below. My thanks to her for allowing me to use them! 

    What is Starfish Wasting Disease? 
    Symptoms of the disease are relatively straightforward:
    1. White colored lesions appear and grow rapidly
    2. There is a loss of body pressure (i.e., turgor)
    3. Body disintegration and autotomy of arms, etc. 
    4. and finally death...
    Bates nicely outlines the various stages of the disease in her paper focusing on Pisaster ochraceus, the ochre star.
    Fig. 2 from Bates' et al. 2009
    Allison Gong recently documented these symptoms in her blog

    Lesions...


    followed by decay and autotomy (i.e., arms begin to shed..)





    The effects DO seem very similar to what happened with the Pycnopodiadie-off
    P1050330
    fr. Jonathan Martin
    But what actually causes the disease?? Sadly, we are just beginning to understand it and so we don't actually know WHAT the causative agent is.  Molecular tests for bacteria haven't confirmed anything.
    Could it be a virus? A fungus? Some strange combination thereof?

    Its also unclear if it is the SAME agent at work in EVERY case. Different species? Different strains? Different diseases?

    The symptoms of the disease have been documented widely: on the west coast of North America. From British Columbia down to the Gulf of California. But also in the Mediterranean and the North Atlantic coast of North America.

    Nothing yet from the Southern Hemisphere.. Australia, New Zealand, etc.

    What Species Does It Affect?
    Wasting disease appears to be pretty widespread across MANY starfish groups. 

    The symptoms of the disease have been observed as early as 1972 from the east coast of North America in the "common" starfish Asterias vulgaris (now called Asterias rubens, pic on the left)

    In 1982, there was a mass die-off of Heliaster kubiniji in the Gulf of California, which was so severe that it led to local extinction in several areas where it had once been abundant. (Image of Asterias by "misenus1", Image of Heliaster by manzanita-pct)
    Northern Sea Star, Asterias vulgarisGulf Sunflower Star

    Eckert's account in the Channel Islands however, documents the widest spread where it was recorded affecting TEN species of most commonly occurring sea stars! Not to mention three sea urchins, two brittle stars, and one species of sea cucumber!

    Disease outbreaks in these species resulted in die-offs and significant population declines.

    In our recent example with Pycnopodia, which looks very much like wasting disease, we saw not just Pycnopodia, but also the sun star- Solaster dawsoni..(pics by Jonathan Martin)
    P1050397P1050395

    Solaster dawsoni feeds on sunflower stars..

    Similarly, Allison observed the bat stars, Patiria miniata feeding on decaying Pisaster ochraceus. Can the disease be conveyed as food? Will we start to see greater spread? 

    But again, we don't know the actual agent of wasting disease. The symptoms might be something that happens in parallel as a result of several different agents.

    Temperature! The Key to Wasting Disease
    Eckert's paper speculated that warmer waters in the Southern California region accompanied the onset of wasting disease in the species they studied.

    Amanda Bates & her team study studied Pisaster ochraceus in British Columbia and studied several variables and how they affected the disease. 


    Indeed, temperature turns out to be a very important factor in the spread of starfish wasting disease! 

    The graph below shows that the prevalence of the disease in starfish under experimental conditions is significantly higher under warmer conditions. This was also reflected by observations in the wild as they saw higher incidence of disease in the summer (June) than in August.
    Figure 3 from Bates et al. 2009
    One final and important observation that Bates and her team recorded was that the disease prevalence was higher in a protected inlet (GM=Grappler Mouth) versus an open wave-swept area (SB=Scott's Bay). 

    This highlights another aspect: What aspect of starfish in the protected inlet vs. the open area to the higher infection rate? 
    • Wave action? (and thus more current and temperature circulation)
    • Freshwater input? resulting in higher vulnerability? (starfish don't tolerate freshwater very easily) Sewage? 
    Aquaria, it was observed, also tended to show higher incidences of infection. 

    So, it appears there seems to be a good correlation with wasting disease prevalence and infection strength with higher temperature. Also being exposed to open ocean conditions vs. more enclosed conditions..

    Starfish Wasting Disease in the Big Picture

    1. Global Warming. If this disease and the ciliate castration parasite are both temperature dependent and we are seeing an across-the-board increase in ocean temperature, this could have significant or even profound effects on populations.  

    Higher rates of diseases and greater vulnerability to diseases affecting not just sea stars, but urchins, and other echinoderms could seriously impact populations of these species. 

    2. Impact? Many if not all of these sea star species (to say nothing of the other possible echinoderms that could be affected) are what's called keystone species, that is, in an ecosystem their presence (or absence) represents a profound effect on many other species. 

    Ochre stars for example affect mussels and other animals in marine ecosystems that cover rocky intertidal bottoms. Sunflower stars are a major predator of everything from snails to sea urchins, and sometimes other starfishes. 

    Diseases like this can decimate or remove these ecologically important species resulting in unforseen results! Just consider this case about abalone and otters as one example..


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    Bobbit worm (Eunice aphroditois)
    Photo by EunJae Underwater Photography
    There's a certain few marine invertebrates which for various reasons capture the imagination of the public and manage to get a foothold into popular culture. Bathynomus-the giant deep sea isopod!  Sea Pigs, such as Scotoplanes and their relatives-weird looking deep-sea sea cucumbers. 

    Among this pantheon of photogenic and/or striking bunch of marine animals is a formidible polychaete worm- in the genus Eunice, also known as the BOBBIT WORM!

    Here's video of this animal's remarkable prowess (more videos are here). These worms  reach 3 m (6 FEET) long and are raptorial predators which use spring loaded jaws to capture their prey... One record holder indicates a worm which was nearly SIX meters in length when collected! 

    Yes. That's basically a worm the size of a large SNAKE with jaws to match!

    This animal has been getting increasingly more exposure as various sites have been introducing marine invertebrates into their blogs and such. This is a good thing for those of us who study marine invertebrates. An animal once known only to specialists is now becoming accessible to everyone..

    I've noticed increasingly however that many of these newer accounts of the Bobbit Worm are missing something.

    Where did such a distinctive NAME come from?  Wired asked where the name came from! And they were not answered.  Even my colleagues at Deep-Sea News asked and were not answered! 

    This question has even been answered in professional venues, which has led to more questions.

    Where does the name "Bobbit Worm" Come from?? 
    In 1993 a case hit the headlines with such a resonant act, it came to be one of the defining news pop culture items of the decade. A woman, Lorena Bobbit, cut off her husband's penis with a knife. The penis was re-attached.  You can read all the gory details on Wikipedia.

    In the late 90s, circa 1993-1995, I was a grad student/ curatorial assistant in Invertebrate Zoology at the California Academy of Sciences.  (I'm ancient like the hills!)  I was working through my Masters and had not yet left for my PhD.

    Part of my time there involved my helping two of the curators, Gary Williams and Terry Gosliner, who were experts in soft corals and nudibranchs, respectively, identify starfish for their upcoming book on Indo-Pacific animals.

    During the research for the book, Gary and Terry returned from a trip to the research dive to the Philippines where they spied a crazy thing. A great story that was told one brisk Friday in San Francisco!

    (story recreated here with new images) A GIANT worm with spring loaded jaws the size of a SNAKE jumped OUT of its burrow and grabbed a freakin' FISH while it was swimming by! Images below by Eunice Khoo (Mer Mate)
    Bobbit wormBobbit worm stretch
    Bobbit worm attack
    Image by Jason Isley
    I didn't believe it. But there it was.

    Bear in mind. Digital cameras were just becoming available. HD underwater Video was nowhere nearly as good as it is today. YouTube was non-existent. The WWW was around but didn't have the size and scope it was today. Most people didn't even KNOW polychaetes were any larger than about a foot long at most. If you saw polychaetes in a coffee table book or marine biology photo magazine you were pretty lucky. The only people who ever saw these huge monstrous worms were divers, scientists and maybe the locals.

    Eventually on one of their trips back, Gosliner and Williams managed to collect a specimen AND a picture of the animal, which they caught a picture of and put into their book, published in 1996...
    (and which is quite good with many verified identifications. Go here to pick up a copy
    The specimen had been identified to genus, Eunice sp. but not to species (I'll explain more below), but Terry Gosliner felt that it a special beast worthy of distinction! And hence the name... (excerpt below from their book)

    So, Dr. Terry Gosliner, curator of mollusks and world expert on nudibranchs was the man who coined the name BOBBIT WORM. At the very least, this is likely the first account of the name in the literature. 
    The timeline and scenario is consistent
    • When divers started looking for books to ID the critters they were seeing, they went to Gosliner et al.'s 1996 ID guide. There were other Indo-Pacific field guides around, but none used the term. 
    • As we entered the era of YouTube, Flickr and kajillion pictures of the Bobbit Worm, how did an obscure 90s reference make it into such common use? The book named the animal and it circulated. 
    • Terry Gosliner verifies himself as the name's originator!
    Some clarification on various myths that have arisen....
    • The Bobbit worm name is based on the act of the knife cuttin off the Bobbit Junk. Further analysis (inappropriate blade type, the worm named for a phallus, etc.) is over thinking it. 
    • Other various stories about female Bobbit worms attacking the genitalia of male Bobbit worms are not just wrong but WAAAY wrong. Polychaetes don't have penises. 
    • And there are no reports (that I know of!) of Bobbit worms attacking tropical men swimmin' around with their junk out!

    So, what species of polychaete IS a Bobbit Worm??
    One major misconception that HAS arisen however, is that because the Bobbit worm is big and obvious that we know what it is! i.e. what species it is...
    Eunice (Polychaete?) Worm Detail
    Image by Mark Atwell
    After Gosliner & Williams collected the worm, they sent it to the Smithsonian's world polychaete expert Kristian Fauchald. He identified it to Eunice but stopped short of the species.

    Why? Because the group is... complicated and this has some bearing on exactly WHAT a Bobbit worm is. Allow me to explain.

    We often see the species name Eunice aphroditois used as the species name for the Bobbit Worm, such as here in Wikipedia and in many other places.  But this is almost certainly an oversimplification.

    Since its original use, the common name has been largely applied to almost any large, predatory polychaete, which most untrained "citizen scientists" such as divers, aquarists, etc.  are generally unable to distinguish.

    For example, is this a "proper" Bobbit worm?  It looks close, but lacks the same kind of jaws. So, probably not. But its not unsual for big, attractive polychaetes to get labelled "Bobbit Worms"

    This for example is another species of Eunice (I think..) but is it a "Bobbit worm"?
    9522 Bobbit worm
    Image by Ken Traub aka Diverken
    The genus Eunice itself, contains OVER 350 accepted species found all around the world! Go here to see a list of them.  Even if you pare down that list to ONLY the really big ones as was done in this article you're still looking at a HUGE number of species that have since fallen under the umbrella term "Bobbit worm."

    In fact, one hugely complicated problem is the definition of the "Eunice aphroditois" species concept itself. A problem outlined here by Sergio Salazar-Vallejo and colleagues.

    The problem breaks down like this:
    The 'Proper" Bobbit Worm was a species originally observed from the Philippines and may or may not be the same species frequently observed in Indonesia and thereabouts in videos and such. In fact, if you read the description above, it was originally thought to be a new species and still may be!

    This paper by Anja Schutlz further outlines methods that we might further understand the questions surrounding the question "What species is the Bobbit worm??" Population genetics of the world populations and further sampling of species from around the world.. (as well as people who can identify them correctly).
    The stuff of nightmares
    Beautiful photo by Eric Cheng! 
    So, conceivably we have not even SEEN the TRUE Bobbit Worm (i.e. the animal originally named as such) as a proper species yet!

    But because the common name "Bobbit Worm" seems to have become rather liberally applied to most large eunicid worms, its likely that name will stick. Not just to Indo-Pacific eunicids but to others..

    and THAT is the rest of the story...  (old-timers joke!)

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    Common brittle star
    Image by MatYts
    Brittle stars are THE most diverse of living echinoderms.

    There are well OVER 2135 species known and many more discovered every day.  However, its not enough to know that there are many KINDS of brittle stars, but another important fact is that they are also some of the most ABUNDANT echinoderms.

    They live everywhere..small cryptical hiding things. Under rocks, in crevices, on other animals, under other animals, buried in sediment, even hiding among OTHER brittle stars!

    Here, for example are brittle stars with their arms emerging from the holdfast (i.e. the anchor) on kelp!
    Brittle Stars Infestation of Holdfast
    Image by Mr. Lobos
    So, sometimes, it strikes one as kind of unusual when all of a sudden you see them literally CARPETING the seafloor!
    Brittle Star Carpet
    Image by Jylnott
    What's going on with these?? When we see this many of some OTHER echinoderm, we often wonder if there is some ecological problem.. For example, with sea urchins, we have a situation where we see "urchin barrens"   and really.. you can't help but wonder what's going on here...
    Purple Urchins
    Image by Anne Crawley
    In this case, the removal of predators has unleashed a huge torrent of sea urchins which devour everything in their path!  Hence the name "barren" because there is naught else but urchin!

    When one sees brittle stars en masse, one cannot then, be a little concerned...
    spiny brittle star
    Image by shawn_broes
    BUT fear not!  As it turns out, these massive aggregations of brittle stars are NATURAL. So while the effect appears the same, perhaps "barren" is not quite as appropriate or even accurate!

    What's going on? 
    So, I'll discuss two kinds of situations where brittle stars literally CARPET the sea bottom.

    In a cold-temperate water genus of brittle stars, called Ophiothrix which you can find in Europe, and in the cold-temperate waters of both the Pacific and Atlantic coasts of North America, they frequently occur in very dense, very abundant numbers!

    How dense?  One paper by G.F. Warner found that the mean population of O. fragilis in the British Islands was found to cover 23% of the ground in some areas, with a mean population density of 1330 indivdiuals per square meter!! 

    For example, here's a couple of nice shots of dense Ophiothrix fragiis beds them from Scotland (and thus the North Atlantic!)
    IMG_0187
    Image by MatYts
    Brittle stars. Ophiothrix fragilis.
    Image by hsacdirk
    This one is a pic of a different, Pacific species but it is a tighter shot and it gives you an idea of how the animals are positioned and what they look like individually.. Note that their arms are ALL extended up into the water!
    brittle star
    Image by echo&dust
    Spines are ALL over these things.. but they aren't necessarily for defense!
    Brittle stars. Ophiothrix fragilis.
    Image by hsacdirk
    Here is a nice video of Ophiothrix in Santa Barbara, where they completely carpet the bottom.  Or in the lower video, from deeper water in Monterey Bay.


    In either case, arms are extended into the water current where their spines capture organic food particles being carried along by the water....Spines are used in conjunction with tube feet for filter feeding!  WATCH those tube feet go!  An example of the original science of this can be found here.


    So, they're feeding. Fine.  WHY ARE THERE SO DANG MANY OF THEM???
    Wall of brittle star
    Image by Kristy Moore
    HOW did they get there???  Did they all migrate there?  Or did they all just kinda... START there and never went anywhere else?

    YES! This paper by Raphael Morgan and Michel Jangoux showed that larvae were encouraged to undergo metamorphosis into adults by the presence of OTHER adults.

    So, in theory, one or others settle down because they are taking advantage of a desirible water/current/food flow. And then another and then another..

    And before ya' know it the larvae in the water sense that other adults are around and THEY settle out and more and MORE...
    Brittle stars
    Imge by MatYts
    ...and BOOM there goes the neighborhood!  Even if you're a voracious Crossaster papposus "rose star" you can only eat and go through so many brittle stars...
    IMG_0175
    Image by MatYts
    If you're an urchin or a starfish trying to make an earnest living, you've got to push all the pesky things out of the way! 
    Unless you're a big ol' monster Pycnopodia- the sunflower star! 


    Filter Feeders can also be found in the deeps! Remember Brittle Star city?? Go here to see a nice write up of this massive colony of Ophiacantha living on a near-Antarctic seamount! 


    But What about in the Deep-Sea???
    I said TWO kinds of brittle star carpets! so here ya' go...    Ophiuroids are crazy abundant in the deep-sea as well.. comprising a HUGE amount of the biomass living on the bottoms!
    exp_R_levin_ophiuroids_001
    Image by Scripps Oceanography
    Here's a dramatic image by my Japanese colleagues at JAMSTEC from the Shinkai 2000 submersible of Ophiura sarsi carpeting the bottom...

    yikes.

    The story is in many ways similar to those at shallow water depth.. juveniles sense the presence of other adults and settle.. but arms are not upheld in the water as readily... What could they be doing down there?

    Many have indicated that they are possibly detritivores. Feeding on dead stuff and other organic material as it falls to the deep-sea bottom... as seen here (and fighting amongst each other for food!)


    In one of my earliest posts.. I also shared the delightful world of these brittle stars as PREDATORS of moving prey! A living carpet of OPHIUROID DEATH!   You can read more on that here. 
    thanks always to Steve Stancyk for the images!

    Ophiuroids! I wouldn't want to mess with a bunch of them in a dark alley! They're takin' over!


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    _MG_2243_0713
    Image by Yellowbeetlebug
    Crab IMG_1357-2
    Image by Jasdivr
    One of the things I find fascinating about sea cucumbers is that they're basically a section of intestine, including the mouth and the anus which has evolved to live on its own. We sometimes think of animals by their most prominent features.. jaws in sharks, eyes in insects...

    But Sea cucumbers are basically a big living gut! and have developed many unusual ways of living with this body plan..
    Sea Cucumber
    Image by WhiteBeachDivers
    It should not be so unusual that the openings to this "living gut" are especially important. The mouth of course, we see used in feeding but in sea cucumbers, of particular significance seems to be the importance of that second, most prominent opening.. the ANUS!
    Another Sea Cucumber Anus
    Awesome image by PacificKlaus
    This is of course, where inorganic sediment is defecated after the animal has eaten and removed the organic material that fuels its diet...

    But SO many other biological functions in sea cucumbers are now being observed in sea cucumbers..

    This account for example about how sea cucumbers can FEED through their ANUS. and of course, the simple fact is that sea cucumbers use the anal opening in order to process water over their internal "gills"...

    OPEN
    Open
    Image by Pacific Klaus
    and shut! 
    Closed
    Another fantastic image by Pacific Klaus
    And by the way.. Pacific Klaus has assembled an AWESOME photo gallery of echinoderm anuses on Flickr here

    But of course, sea cucumbers can host several commensal animals. That is, animals which live, in or around the animal as a habitat but which bring neither harm nor advantage to the host sea cucumber..

    The most striking example is the "fish-in-sea cucumber-anus" Pearl Fish. Go here to see this. 
    or there's video of course...


    and just because I can, lets not forget: Anal Teeth!
    Sea Cucumber Anus
    Image by PacificKlaus
    Awhile back I wrote about flatworms living in sea cucumbers and sea urchins..
    But another evocative animal living in sea cucumber anuses?  These little crabs!
    _MG_2243_0713
    Image by Yellowbeetlebug
    Many of these have been called Lissocarcinus throughout the internet.. but I'm not sure how dependable those names are. They appear to be scavengers taking advantage of any leftover food ..

    Is the anal habitation a matter of opportunity? Regular behavior? Species specific?

    But clearly, they do seem to make the most out of uh... living in the shadow of greatness...
    Sea Cucumber Crab - Where the Sun don't Shine from liquidguru on Vimeo.

    Another
    DSC_0353
    Image by Martin "El Grande" Sequerah
    Interestingly, there are also photo accounts of these shrimps living around sea cucumber anuses.. perhaps to take advantage of other organic material?
    IMG_2336
    Image by Eric Francis
    Here are more shrimp+crab anal assemblages...
    Lembeh Strait
    Image by Swaflyboy
    Incidental occurrence? or preference?
    shrimp on sea cucumber 2
    Image by ScubaSchnauzer
    This shrimp seems to have found itself completely embedded in sea cucumber anus!
    Imperator Shrimp - Periclimenes Imperator stuck in the anus of a Sea Cucumber
    Image by Prillfish
    Many questions-what do the crabs and shrimps get out of this? Are they species specific? Is this really a region specific habitat? Or do they just use the whole animal as a house with the anus as a door?

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    Crab on Crinoid
    Image by Raymond Dy
    Crinoids are always that weird member of the Echinodermata that seems to get out from under the "weird animals" category.. maybe because they can be so ethereal and frankly, just so damn photogenic!

    So, this week: Some Feather Star Fascination! Some Charismatic Crinoids!  Here's some neat "best of" links about crinoids:
    1. The Crinoid Life Cycle: How Feather Stars (comatulid crinoids) show their relationship to stalked crinoids!(here)
    2. Urchins Attack! And Why Feather Stars Swim (here
    More Swimming!
    2013 Shetland 093 301 Fetlar crinoid
    Image by tdpriest
    Feather star
    Image by Jules Nene
    031_adj_DSC0536 swimming crinoid
    Image by Erwin Poliakoff
    Flying feather star
    Image by Raymond Dy
    Not only was this one caught swimming-but there's a crab holdin' on! Yowee!
    Crab on Crinoid
    Image by Raymond Dy
    and of course this video that is just about as soothing as anything you will watch an echinoderm do..

    A crazy Splash of crinoid color!
    F016
    Image by Sea Dog Diver
    A colorful but more muted color crinoid combo!
    Crinoids
    Image by Rene Cazalens
    This one seems to be "standing" on its arms. Unusual behavior!?
    Standing Crinoid
    Image by Troy_Williams
    A fantastic one called "Crinoid Corona"
    crinoid corona
    Another one by Troy_Williams
    This one is called "Honshu crinoid sunburst." Nice. 
    Hoshu crinoid sunburst
    and yet another by Troy_Williams
    A nice shot showing crinoid and associated fish..
    7-27 zanpa boat crinoid and fish
    Image by Troy_Williams
    Wow! An unusual shot by Simon Marsh
    Crinoid
    A nicely posed Antarctic Promachocrinus kerguelenensis (maybe)
    Crinoid
    Image by Icy_Sea_Slugs

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    P1050360
    Image by Jon Martin
    UPDATE: You can upload new pics of starfish wasting disease to this website (iNaturalist). Help track its progression!

    Since I originally reported on the big Pycnopodia starfish die off in British Columbia, I've gone on to invoke Starfish Wasting disease which has led to much discussion and reporting of the issue all along the west coast of North America, including concerns invoking the die off of the east coast starfish Asterias, which is closely related.
    Meeting of the seastars
    Image by Jeff Goddard
    New developments since I last wrote:

    The disease (?) occurrence in British Columbia seems to be reported now from several places:
    Whytecliff Park (video here),
    Kelvin Grove (video here),
    Howe Sound (account at Aquablog) ,
    Croker Island, Sechelt Inlet and ... (I will continue to update).(thanks to Jon Martin, Neil McDaniel and others for their pics and records)

    Could Wasting disease also be headed for Washington? (via KUOW.org)

    The number of taxa seems to be broadening but is most acutely observed in Pycnopodia. But other accounts in BC waters have been seen in Mediaster, Dermasterias, and Solaster.
    P1050449
    image by Jon Martin
    Other places starfish wasting disease is observed (e.g., California) it seems to be more focused on asteriids, such as Pisaster. An excellent summary of what the disease in California looks like can be found HERE.

    Why Should We care? 
    With all the media picking up the story and carrying it around to multiple outlets, at some point someone will get beyond the "weird news" twist that has been put on the articles and ask "So What?" Here are 5 reasons I think understanding why this die-off MUST be studied.

    1. An Endemic Starfish Fauna.  
         A few years ago I wrote about the phylogenetic (aka the family tree) of forcipulate starfishes. The blog I wrote about it was here (w/paper cited within)

    Basically, one of the important facts was that all of the asteriid starfishes in this area, including Pycnopodia (the sunflower starfish), Pisaster (the ochre star), Evasterias, Leptasterias, etc. on the Pacific coast of North America are ENDEMIC TO THE COAST.

    That means, you could see a starfish which resembles Pycnopodia in Australia or Mexico and it will have LESS relationship to Pycnopodia than Pycnopodia has to Pisaster!

    Bottom line: You won't find these starfish species anywhere else in the world. These animals are an important part of the marine ecology of the Pacific coast of North America.


    2. Aesthetic & Cultural History
    Ed Ricketts, 1937
    Image by sjonnie van der kist
    “What do they find to study?” Hazel continued. “They’re just starfish. There’s millions of ’em around. I could get you a million of ’em.”
    “They’re complicated and interesting animals,” Doc said a little defensively.
    The starfish on the west coast of North America have become iconic. Pisaster ochraceus, aka the Ochre Star is THE model for the Keystone Species in Ecology.  The starfish of the west coast were in John Steinbeck's famous novel Cannery Row as part of the rich career of Ed "Doc" Ricketts:
    What if there weren't a million of em any more?  More on this below under #5-ecological impacts. These are animals which have become part of our culture. Conservation of these species is important.

    Montastraea Cavernosa With Active Black Band Infection
    Image by CIOERT
    3. We don't know what causes it. At the moment, there are a bunch of ideas. Bacteria. Virus. Some
    kind of microbe?  But as we see in Coral bleaching diseases, microbes are present.
    They might be the cause OR they might be the RESULT of some shift in their surroundings? such as temperature or overall water quality. Sea stars DO have a natural microbial fauna (here) What if that fauna/flora goes bad because of changes in some greater part of their environment?

    If this isn't a communicable disease per se but is instead more of a series of symptoms related to poor or changing environmental factors, which activates/corrupts/modifies that fauna, THAT could be a concern which leads us to our next point...




    4. Canary in a Coal Mine- Global Warming? I think the thing that always concerns me about this whole thing is whether this whole phenomena-the die offs in British Columbia, the wasting disease observations in California and elsewhere - are all tied to a particular environmental change. I have written about echinoderms as the "canary in the coal mine" animals before..but for specific environments such as Antarctica. What if something is happening and this is an early warning that we aren't picking up on?

    The original paper by Amanda Bates (here) observed that wasting disease seemed to be most acute when it was warmer.  What happens if Starfish Wasting Disease takes on the scale of the various coral wasting diseases?  Vigilance and data are an ongoing concern....

    5. Widespread Ecological Impact. Here's the million dollar issue.. What happens if diseases change abundance or remove these species from their habitats? WHAT HAPPENS? What COULD happen?
    Sea Stars
    Image by Phil Williamson
    Sunflower Star at Rest
    Image by Daniel Johnson
    The thing is, that BOTH of these species occupy important ecological positions. As mentioned earlier, Pisaster is a keystone species. The presence or absence of a keystone species in an ecosystem can dramatically change the interactions of that ecosystem. 

    For example, Ochre stars (Pisaster ochraceus) removed from the intertidal would likely result in a significant overgrowth of mussels and other invertebrates which ochre stars typically feed upon. Mussels might come to dominate an ecosystem and prevent other animals from inhabiting that area. There could be a cascade of other consequences of course...

    Similarly, Pycnopodia is a dominant predator of MANY other invertebrates species, sea urchins, abalone, snails, clams, etc.

    But MORE than that there could be an unpredictable cascade resulting from fluctuating populations of any of these taxa. An increase in sea urchins, resulting from an absent predatory starfish, for example might result in additional sea urchin "barrens" (as I've described here)

    What is perhaps most concerning is how MANY starfish species seem to be affected. Many of their ecological roles are poorly understood but are likely to be important. The effect on the ecosystem is likely to be significant. 

    Thanks to many discussions at Science Online Oceans this past weekend for discussions that inspired this post! 



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    October 26, 2013. UPDATED with more! 

    PARIS! I've just arrived and hard at work with my colleagues at the Museum national d'Histoire naturelle!  But this week has been crazy. Wi-fi down, taking care of last minute projects and so forth on top of travel and jet lag.

    So this week the blog is about a curious set of street art I've seen. OCTOPUSES all around Paris! 

    These are often painted or posted surreptitiously around Paris in strange corners and rarely travelled nooks around the city. Based on the arm length and overall appearance they appear to most closely resemble the "dumbo" octopus -something like Grimpateuthis or Opisthoteuthis but I'm pretty sure the artist has mainly taken the image from his own imagination...
                               dumbo octopus

    This one actually bears a striking resemblance





    They all have the same basic shape but vary by character....  The following I have seen...









    These I found on Flickr and elsewhere...  
    KRUSTY! 
    Gzup_8449 rue du Temple Paris 03
    image by meuh1246
    The old Japanese superhero Spectreman! 
    Gzup_3585 passage Lisa Paris 11
    Image by meuh1246
    Cyclops from the X-Men
    Gzup_5111 rue Vavin Paris 06
    Image by meuh 1246
    King cyclopopod! 
    Gzup_8666 rue Jean-Marie Jego Paris 13

    and extra bonus! GIANT CEPHALOPOD mounted on a Paris building wall!


    Some Halloween fun next week!


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