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Articles on this Page
- 02/16/13--17:59: _Saturday Night: WHA...
- 02/20/13--05:44: _The Anus as a Secon...
- 02/22/13--11:34: _Extra! Solaster fee...
- 02/24/13--08:13: _One of the most gor...
- 02/26/13--21:09: _Stalked Crinoids! A...
- 03/05/13--21:52: _Off topic: Stunning...
- 03/12/13--22:57: _A spotlight on Echi...
- 03/20/13--07:57: _Antarctic Echinoder...
- 03/27/13--05:07: _Off-topic! Fire Wor...
- 04/02/13--22:16: _Happy Spring! Here'...
- 04/09/13--15:25: _Starfish or Sea Sta...
- 04/16/13--23:42: _Natural History Mee...
- 04/19/13--06:34: _More mysteries with...
- 04/23/13--22:39: _How many starfish s...
- 04/30/13--22:06: _Flukes in Cukes! Fl...
- 05/07/13--19:29: _Flatworm Color Expl...
- 05/14/13--22:29: _Biophysics Meets Ol...
- 05/21/13--22:05: _Starfish Macro Shot...
- 05/28/13--22:49: _New "Tam O Shanter"...
- 06/04/13--19:47: _FIRE Urchins! Brill...
- 02/16/13--17:59: Saturday Night: WHAT is this thing?
- 02/20/13--05:44: The Anus as a Second Mouth! A Sea Cucumber that feeds via its butt!
- 02/22/13--11:34: Extra! Solaster feeding caught forever in the museum!
- 02/24/13--08:13: One of the most gorgeous brittle star videos ever shot!
- 02/26/13--21:09: Stalked Crinoids! A Forest of Fossils!
- 03/05/13--21:52: Off topic: Stunning Crab Photos from Arthur Anker!
- 03/12/13--22:57: A spotlight on Echinoderm Art
- 03/20/13--07:57: Antarctic Echinoderms:Canary in a Coal Mine for Ocean Acidification?
- 03/27/13--05:07: Off-topic! Fire Worms! Chloeia Video & Picture round up!
- 04/09/13--15:25: Starfish or Sea Star? Asteroid? 5th Anniversary Post!!
- Starfish/Sea Star is a term that VERY SPECIFICALLY refers to the ASTEROIDEA-one of five living classes within the phylum Echinodermata (the others include sea urchins, sea cucumbers, crinoids, and ophiuroids).
- It is incorrect to refer to OPHIUROIDS as "sea stars" or "starfish", per se. Ophiuroids are an altogether DIFFERENT class of animals from asteroids. Go HERE to see some characters that tell them apart. Common names of ophiuroids include: brittle stars, serpent stars, basket stars. I find it acceptable that certain echinoderms are referred to as "XXXX stars" under certain circumstances. A separate class of echinoderm-the Crinoidea (lacking a stalk), for example are often called "Feather stars." I'm cool with that. The specific terms "sea stars" and "starfish" should only be applied to ASTEROIDS.
- Note that this is one of the few groups in which the common name DOES correspond to a 'real' classification. Terms such as "crab", "coral", or "jellyfish" actually do NOT refer to a single natural classification of animal-but rather several similar looking kinds of often distantly related animals. This video about "jellyfish" explains the issue nicely:
- 04/16/13--23:42: Natural History Meets Data Mining! A case study in Porania pulvillus
- 04/19/13--06:34: More mysteries with Porania pulvillus! Yay for Crowd Sourcing!
- There are about 1900 species of starfish and that number is climbing.
- They live everywhere in the ocean! Especially in cold-water habitats like the deep-sea!
- The family Goniasteridae is the MOST diverse (i.e. most number of species)
- MANY more species of asteroids remain to be discovered!
- The fossil record shows that starfish have been around for a LONG time, since before big reptiles roamed the Earth!
- 05/07/13--19:29: Flatworm Color Explosion! Off topic! A Panoply of Playhelminths!
- 05/21/13--22:05: Starfish Macro Shots! Up Close Tropical Edition!
- Mostly deep-sea urchins found all over the world (many in greater than 1500 m depths-in NZ they range from 100 to 5000 m!), but with some shallow water relatives (aka the Fire urchins, I'll save these for another day)
- They often have very sharp and poisonous spines. And yes, the deep-sea ones too...
- They "walk" around on the sea bottom with special spines that have hoof like tips
- They were described FIRST as fossils and the living animals were found AFTER...
Working late alone in the lab, going through a dish of marine inverts collected from a random sample in the Pacific Ocean and you find...something.
Sometimes someone is around to share it with, sometimes not. What does THAT feel like? This video isn't mine but it gives me the same feeling of discovery.
I just found this and I don't know what it is. THAT's saying something..
|Image by Ken-Ichi|
This week, Echinoblog brings you:
A sea cucumber that feeds not just using its mouth but ALSO via its butt!!
First, Let's look at some basics...
Jaeckle and Strathmann were studying the Pacific Northwest species Parastichopus californicus-the handsome fellow pictured above (and below)! These occur along the west coast of North America in relatively shallow water...
|Image by Bill Pennell|
|Image by bswift|
As a generaltiy-sea cucumbers can pump quite a bit of water in and out through their anus-with tropical species measured between 40 to 860 milliliters/hour..that translates to about 3.6 to 4 cups of water per hour!
Sea cucumbers are essentially a big fleshy tube with a mouth and a butt that pumps water through itself! Here's the basic anatomy below...
Folllowing the trail of traced algae through the sea cucumber, Jaeckle and Strathmann tracked the isotopes throughout the body and found out where they were most abundant.
Enter The Rete Mirabile! (this sounds like a great episode of Star Trek doesn't it?) Basically after exposing the sea cucumber to tagged algae they found the tags taken in and were present in highest abundance in the Rete Mirabile which connects the respiratory trees with the gut..
This supports the notion that organic food is drawn in from the respiratory trees and eventually transferred to the gut..
|Fig. 3 from Jaeckle & Strathmann|
On top of everything else, histology of the INSIDE of the respiratory trees shows internal tissues that you might expect to find in a gut: such as microvilli (tiny finger like doodahs that serve to absorb or secrete. We have these in our intestine) as well as certain kinds of cells in the stomach lining that are recognized in other animals for digesting food.
Note above that they also found tiny ciliates (protozoans) swimming around inside living commensally. ANOTHER feature common to spaces where food is digested.
|Image by bswift|
But the evidence above suggests but rather something more akin to digestion or UPTAKE of nutrient-like material
In other words: They use their anus as a SECOND MOUTH!
This phenomena is what the authors term "Bipolar Feeding"
To be sure, its not likely that this means of feeding is as substantial as its primary feeding mode (taking organic materials from sediment or from the bottoms via the mouth) but it does appear to be significant. Also, obtaining food in this way may be an important way to supplement its main feeding mode.
Perhaps the sea cucumber version of an apéritif with dinner?
How does this fit into the "Big Picture"??
Another indicator of how echinoderms might be the ecological "canaries in the coal mine" perhaps?
Information like this may seem like an unusual natural history factoid but conceivably things like this can ultimately be VERY important to the big picture...
and the prey (where the arm comes from)
Solaster is one of the few starfish which is known to feed primarily (at least in some species) on OTHER starfish! Here was something I wroteawhile back on the Pacific Solaster dawsoni...
and here is a nice pic of the North Pacific S. dawsoni feeding on Hippasteria
It is so fearsome that EVEN the sunflower star Pycnopodia RUNS from it!
andhere's a nice bit about when starfish are eating and uh... overreach...
NOM! NOM! NOM!
|Isocrinid stalked crinoids from the Mariana Arc in the tropical Pacific.via NOAA|
So, the other day someone complained to me that the Echinoblog didn't do enough with fossils. So, this week FOSSIL CRINOIDS to the MAX!
The fossils below look like the ones above..kinda. Isocrinids? from the Jurassic. Image by Kevin Zim.
Some nice crinoids from the Houston Museum of Natural Science. Not sure which species. Images by malts8
These are the crinoid Jimbacrinus bostocki from the Permian of Australia. More info at the Museum Victoria page here. Images by malts8
An awesome rhombiferan (Caryocrinities ornatus)-not quite a crinoid-but something closely related. Another image by malts8
Pentacrinus (Mesozoic to Cenozoic) Image by fa11ing_away
A nice Seirocrinus subangilaris from the Jurassic Poseidonia slate of Germany. Image by Zoltan.sylvester
Phanocrinus formosas and Tholocrinus spinosus from the Mississippian-Glen Dean Formation in Grayson Co. KY. Image by malts8
Cool looking Zeacrinites magnoliaeformis fr. the Mississippian-glen Dean Formation in Grayson Co., YI. Image by malts8
Onychocrinus exsculptus. Mississippian? (Paleozoic) Image From the Houston Museum of Natural Science
More from the Mississippian! Talarocrinus planus. Image by G.S. Springer
From the Mississippian of Iowa. Dichocrinus inornatus, and Rhodocrinites kirbyi. These fossil pics from Piedmont Fossil- The Iowa Historical Museum
some nice fossiliferous limestone
A veritable FOREST of crinoids! Rhodocrinites kirbyi, Dichocrinus inornatus, Pachylocrinus globosus, and Rhodocrinus nanus along with unidentified brachiopod and bryozoan.
Agaricocrinus splendens from the Mississippian
Onychocrinus exculptus from the Mississippian of Crawfordsville Indiana
So, remember awhile back when I wrote this controversial post about swimming/floating crinoids?? There was this diagram that had been presented about how this one crinoid, Scyphocrinites enjoyed a pelagic type lifestyle with a positively buoyant "float"
Here are some neat photos of what these floats look like in similar crinoid species.
In this case, from Camarocrinus ulrichi. Images by malts8
They are sometimes abundant in the field!
And down in the Cambrian we have...Gogia, an Eocrinid blastozoan (a different but closely related group of echinoderms similar to proper crinoids) Cambrian, from the Langston Formation, Spence ShaleImage by malts8
Are there echinoderms I'm not giving enough time to? Let me know!
Today, a little diversion from echinoderm as we feature, once again, the stunning invertebrate zoology photography of Arthur Anker featuring some of his favorite animals!
A "strawberry crab" (Pelia mutica) from the Honduras
wow! A festive decorator spider crab called Cyclax suborbicularis (Majidae) from Moorea, French Polynesia
A "christmas lights crab (Paractaea rufopunctata)
The spectacular deep-water crab Rochinia crassa
An awesome looking leucosiid crab, Heteronucia venusta from Guam
A stunning Chilean hermit crab (Pagurus edwardsi) infested by a parasitic barnacle (=a rhizocephalan called Peltogasterella gracilis)
A striking striped crab, Liopetrolisthes mitra
An interesting grapsid crab, from French Polynesia
A gorgeous polka dot xanthid crab, Cycloxanthops vittatus from Panama
Stunning red xanthid crab, Liomera rubra from Guam
Fire crab! (Hirsutodynomene sp.)
More polka dots! (Trapezia tigrina)
A flat-rock elbow crab, Cryptopodia fornicata
and wow..there's more which I will add in another post some day!
Things got a bit busy this week and I've been discovering the wonders of the natural history side of DeviantArt!
MANY creative and wonderful artists out there and I thought it would be cool to showcase some of the notable ones, especially the ones that can be compared against the "originals"
Frankly, I'm pretty impressed. At one time, a LOT of these animals were known only to a handful of specialists in the world. And NOW?People make them into art!! That's amazing!
Here's a few...
Enypniastes! The deep-sea Swimming Sea cucumber! I blogged about these HERE.
Enypniastes eximia by *NocturnalSea on deviantART
Swimming Sea Cucumber Enypniastes eximia by ~JadaFitch on deviantART
Swimming Sea Cucumber by ~veeohlay on deviantART
Here are some video of the original inspiration!
SEA PIGS! The sea cucumber called Scotoplanes! I wrote a bit on this HERE.
Sea Pig by ~YavKementari on deviantART
and holiday classics!
Yeti Crab Santa by *NocturnalSea on href="http://www.deviantart.com">deviantART
An interesting one with a Chinese art theme
Sea Pigs by ~HangingLeaf on deviantART
SEA PIG HUMOR!
Sea Pig by ~ToonSkribblez on deviantART
A digital sea pig
cute as a sea pig by ~apostlebird on deviantART
Here's a link to a neat one called "Sea Pig Nouveau" that sadly, was not embeddable..but click here.
and of course, here's the original..
What follows here are some PALEOZOIC fossils, with added colors and "reconstructed" onto a Paleozoic sea bottom as if they were alive...
I try to compare some of these with actual fossils...
Ophiocistioids!Strange Paleozoic forms! I wrote about these only awhile ago HERE.
Volchovia species by =avancna on deviantART
Sollasina and Eucladia by =avancna on deviantART
Here is an actual fossil of the ophiocistioid Eucladia from Yale's collection
Cystoid echinodermsfrom the Paleozoic! I'll blog more about the various Paleozoic echinoderms some day, but there's easily as many extinct echinoderm fossil groups (most of them with stems) as living groups. This image has a nice assortment of them from the Ordovician of New York..
Glyptocystites multiporus by =avancna on deviantART
Here are the three primary critters for comparison! The light olive one in the upper right corner, wrapped around the bryozoans is called Cupulocrinus jewetti
|Image by Paleoportal. Photo by Joe Koniecki|
|Image from Paleoportal. Photo by Joe Koniecki|
|Image from Paleoportal. Photo by Joe Koniecki|
This week a 2011 vol. 119(5): 457-466 paper from the Journal of Geology by Antarctic biologist James McClintock, my colleagues at the University of Alabama (M. Amsler, R. Angus, R.C. Challener, J.B. Schram, C.D. Amsler), myself and colleagues at the University of South Florida (J. Cuce and B. Baker).
Our paper addresses how Antarctic echinoderms but specifically sea stars (=starfish) and brittle stars are likely to be vulnerable as the climate changes, creating a more acidic ocean environment.
Here is a quick video that nicely summarizes the broader phenomena of Ocean Acidification (abbreviated OA)
But here is where we add further details-the acidification? affects different kinds of calcium carbonate (the material which composes shells, coral skeletons, etc.) differently...
Most of the shells and skeletons that you read about in the news are usually made either out of different forms of calcium carbonate-either aragonite (wikipedia has a nice summary here) or calcite. Aragonite is usually what's seen as associated with shells, skeletons, etc..
But, of course, echinoderms being echinoderms have something a little different going on... Echinoderms have skeletons with a high concentration of magnesium (Mg).
Their skeletons are composed of Mg-calcite (magnesium calcite)
One can see many recent stories about how aragonite in shells is easily dissolved by ocean acidification.
Mg-calcite is even MORE soluble (and more vulnerable) than aragonite!
Looking at Mg-calcite in Antarctic Echinoderms
Of all the echinoderms? Which had the HIGHEST amount of Mg-calcite by % weight??
Several species of Starfish!
I would note that ophiuroids were not heavily sampled-below but in all liklihood they are just as if not more important here..
Specfically, this very widespread species, Porania antarctica dsplayed among the HIGHEST % weight of Mg-Calcite
|Photo by Dirk Shories at this site.|
This total amount of Mg-calcite was compared relative to OTHER %of Wt. values across different latitudes (0=equator, higher = closer to Antarctica)
2. Mg-calcite is most vulnerable to dissolution.A study on coralline algae (that's algae which builds a skeleton for itself using the mineral Mg-calcite) showed that when 8-12% by wt. of a calcite skeleton is composed of Mg-calcite it becomes HIGHLY soluble.. Look above at the Table 2 from the paper most sea stars have 9 to 10% by wt. Mg-calcite skeletons!
|Image by Ben Naden|
This one shows some burrowing action at the end...
Here's one eating...
This one is a stunning iridescent green! Image by friscodive
Chloeia fusca. Image by Ben Naden
Another similar one. Image by divemecressi
And yet another by friscodive
An awesome one from the Panama Canal. Image by Arthur Anker
Back atcha next week with more echinoderm blog love!
|Fantastic image by Arthur Anker-Colochirus quadrangularis|
My thanks again to Arthur Anker, WildSingapore and other photographers who have put their images up to enjoy!
|Fantastic image by Arthur Anker-Colochirus quadrangularis|
|Cercodemas anceps by Arthur Anker|
A nice one of Cercodemas with the feeding arms extended
And here's BOTH Cercodemaas AND Colochirus!
Pseudocolochirus olivaceus. Images below by Arthur Anker, Singapore Marine Biodiversity Survey.
Another nice Pseudocolochirus shot by Jeff Mullins (underwater komodo)
The feeding end of Pseudocolochirus. Image by Arne Kuilman
A nice close up of the tentacles in a sea apple. Image by Pat M. Williams
and finally, here's a video of one in its habitat (this one from Hong Kong)
|thanks to Paul G. for the photo!|
A topic that has found bitter and vicious debate at museums, aquariums, marine biology and even paleontology programs around the world!
Undoubtedly upon this post reaching public circulation, many of my colleagues will probably stop returning my email and spit upon me as I walk by them (although some of them do that anyway!)
I speak of course, of the dreaded "Starfish or Sea star (seastar)??" controversy!
Which common name should we use for these frequently encountered and familiar marine animals???
But where to start? Let's define some terms, so this discussion doesn't get completely out of hand.
Let us make no mistake-when we talk of this debate that we speak of members of the ASTEROIDEA.
These reflect various arguments I have heard/collected over the years. While I have my conclusions at the bottom...please feel free to take these different perspectives to your classrooms, aquarium education courses, and grad school discussion groups to discuss at your pleasure! Yell at me in the comments if you wish!
1. The term "asteroid" (from class Asteroidea)
We Should Use the Term Asteroid Because:
The latin name from the group, ASTEROIDEA was officially put to paper by the notedFrench zoologist Henri Marie Ducrotay de Blainvillein 1830 from the Greek aster and eidos referring to "star (as in the sky)" and "form or likeness."
Nouns are derived from the scientific name.. so "asteroids" is technically the proper term for animals that we would refer to as "sea stars" or "starfish".
We Should NOT Use: No, we can't use the term "asteroid" because it might be confused with a giant space rock hurtling through space! OH NOES!
|From Nat Geo article about asteroid collision|
1. The word starfish is widely used and "I" like it.So why change what ain't broke?
Google recovers 13, 200,000 hits relating to "starfish"including use in religion, politics, obscene rock lyrics, hitting the bed and splaying out on the surface, charity organizations, nuclear bombs, and yes, sometimes it even refers to animals!
2. So what if the word is a misnomer? Plenty of words in the English language are inaccurate. Greenland is icy and Iceland is green! Sea horses aren't horses! Why can't we just put up with one more? That's life! C'est la vie!
3. Starfish is the oldest known western term. (thanksto John Lawrence, at USF for the info) According to the Oxford English Dictionary (OED) this dates back to 1538 referring to "Stella, a sterre, also a sterrefyshe."(from Elvot, dic.) This usage corresponds to the first definitiion given for "fish" in the OED: "In popular language, any animal living exclusively in the water"
These days of course, our terminology has been much revised based on tons of evidence showing classifications among animals and we acknowledge that "fishe" had a much different meaning 475 years ago, but the term has stuck with us and its not likely to be going away anytime soon.
I'll bet that scientists and students are probably not as big a majority user of the term "starfish" as they believe themselves to be. The term is widely used throughout the many aforementioned outside disciplines and probably won't find much change even if scientists begin to radically suppress the term...
The term is inaccurate since any MODERN definition of "fish" refers to proper vertebrates and NOT invertebrates! Inaccurate terms are SO confusing! People and students who have not had basic biology will not know that asteroids are NOT fish! Oh Noes!
3. The term "Sea Star (or Seastar)"? (yes there's even a controversy over whether "sea star" is one or two words!)
USE the term Sea Star!
1. The term is more accurate. Asteroids aren't true fish so why call them that ?? (other than historical tradition, which is dumb!).
1. The term Sea Star gets less use than Starfish. "Seastar" (one word gets 2,660,000 hits) but note that "sea star" (two words gets 475,000,000 hits-but many of these may be random combinations of "sea" and "star"). Its dumb that we use such a wishy washy word that other countries use!
2. Sea Stars are not stars. Asteroids may not be "fish" but nor are they big burning balls of space gas! I once used the "sea stars are not stars" thing jokingly-but it turns out, the reference to stellar bodies has a real basis!
The FIRST definition for "sea star" in the OE dictionary (and indeed Websters as well) (date uncertain) is of a "star which guides mariners at sea", the Star of the Sea, with only the SECOND definition referring to proper asteroids.
|Blue Star. by negombo83 on Flickr|
1569... A kind of fishe called Stella or Sea starre, bycause it hath the figure of a painted starre (fr. Fenton-Secret Wond. Nature)Curiously a subsequent definition reads
1594..The fishes called Sea-starres, that burne one another by excessive heat. (fr.Nashe, Unfort. Trav.)3. Asteroids are not always star-shaped! Sometimes they are pentagonal...almost to the point of being round..
Other times flat and almost paper-like..
And still others can be almost ball-shaped
In the 90s (or thereabouts) there was a huge revolution in educational programs across museums and aquariums throughout the US, and inevitably beyond. Many of the various common names ended up getting names that people felt were more accurate. So jellyfish were called sea jellies. Hagfish were called sea hags and so on.
At about the same time was the big "political correctness" revolution from the late 80s, early 90s which was intended at diffusing offense and infusing more respectful terminology among public and political dialog-with extensive changes to almost all terminology.Here is a full workup of that scene at Wikipedia.
Naturally, it was widely assumed that common names in science had befallen the same fate. But as indicated above.. the term "sea star" has been around since the 1700s. And across different languages. And since, ultimately, asteroids DON'T really care WHAT you call them, it does seem unecessary to apply political correctness to echinoderms.
Are European terms the only one we should consider?
At a certain point in this discussion it becomes readily apparent that the "common name" argument for asteroids emphasizes the western/English terms. Do terms for starfish in other languages offer more attractive options? Let's look at a few!
*hitode (ヒトデ). This word means "palm" in Japanese.Here is a post I wrote about Japanese starfish names! Records of the term hitode date back to 1712!
*tapak sulaiman.In Malay, this word literally translates to "Solomon's Footprint"! Snazzy, eh?
*불가사리 In Korean, the word for starfish refers to "Immortality"!!!
(my thanks to Yoichi Kogure, Marcus, Tai-Lin and Taekjun for their helpful insights!)
These are all awesome. and hmm.. Solomon's Footprint is a pretty cool name for an asteroid!
Ultimately, though these terms seem to work out best in their homelands where the cultural context makes the terms more useful (and perhaps less confusing in English). Although I dunno... I'm still kinda fond of Solomon's footprint..
What was the oldest name again?
1569: sea starre
Yup. Its "starfish" and not technically "sea star"..so if you're a big taxonomic synonymy fan but not a big fan of "starfish"..uh.. sorry...
Within the international rules that dictate proper scientific names for animal species, it is generally accepted that the OLDEST term has seniority over the others.
But does that change anything for people who prefer "sea star"? Probably not. These rules generally only apply to the proper Latin species names and not the "common" or popular names. But as far as established 'legal' criteria goes this is one of the few which seems to apply. And it does seem to be the "senior" name...
Finish it up! I ain't got all day!
These are things that are not negotiable
1. Asteroids are starfish/sea stars. NOT ophiuroids (aka brittle stars). I often see a wide variety of individuals in the popular arena apply the terms mistakenly. That is improper use and thus, is disapproved of. Hrrumph!! Double Hrrmumph! PLEASE STOP IT!
2. The term "asteroid" is technically correct. As indicated above, this is a NOUN based on the actual scientific name of the animal? HERE YOU GO. But of course, we could still confuse a big space rock with a giant interstellar starfish.
I prefer to use "asteroid" as a scientist of course, but barring that?
WHY NOT USE ALL THE TERMS?
Many languages have different words for the same thing. I accept that there are different words with the same meaning. I trust context to decide usage. I tend to use "sea star" around students and/or an audience that might not be familiar with asteroids. I use "starfish" around people who know better.. and I use "asteroid" among my colleagues..but obviously there is interchange.
But yes, please know that a "starfish" is NOT a fish before you begin using it. :-)
Over the years, the whole argument has started to sound kind of silly...
1. We can't use "asteroid" because we could confuse it with a space rock! Oh NOES!
2. Okay. Let's use starfish or sea star instead.
3. We CAN'T use starfish because people would confuse it with a FISH! But I HATE the term "sea star!" Not always star-shaped! Blah! blah!
6. Oh NOES! Space Rock!
HAPPY 5th ANNIVERSARY from the Echinoblog!
|Image by Geir Friestad via Flickr. Norway I think.|
|from this EOL page via SERPENT Media Archive|
Note that the white "dots" above and the finger-like yellow bits below are the papulae- aka the gills! This is how the animal "breathes".. Image by Mark Craig
In 1915, zoologist James F. Gemmill described what he observed to be filter feeding using the numerous tiny cillia covering the body of this species.
Dr. Gemmill was quite an authority..being an M.A., M.D. D.Sc, F. Z.S."!!! And is pretty well known historically for a number of significant contributions. He dropped little red carmine particles (basically a red dye made up of a fine powder) on P. pulvillus and watched them move over the surface..
A quick reminder about basic biology of this (and all starfish). The epidermis COVERS the body! The epidermis is in turn covered by tiny hair-like structures called cilia, which are usually in constant motion.
These little particles were moved over the body and apparently headed towards the mouth. Here's his diagram showing the little arrows apparently indicating how water was flowing to the mouth.
|Fig. 2 from Gemmill 1915|
|Image by Christine Howson via Flickr|
Is this Porania pulvillus getting ready for a big banquet? Or is this the echinoderm version of those "1 dog, 1 pig, and a cat" pet adventure stories?
|Image by www.ilreporter.com|
It turns out that what we are seeing here is probably something unreported! NEW!! A previously undocumented feeding interaction!!
|From this EOL page via SERPENT|
Here's a nicer pic of the sea pen...
|Image by Jarle Strømodden via Flickr|
Again-this was a NEW discovery! What does it mean for this animal's ecology? Does it mainly feed on yummy cnidarians? Is the species more opportunistic than thought? More predatory than previously thought??
And of course.. there's the impact on the bottom fauna.... I've written about goniasterids that feed on deep-sea coral (here) and here's a video about them from MBARI a few years back...
These types of interactions are important owing to our interest in deep-sea corals and their role in biodiversity and conservation of deep-sea ecosystems..
But after looking at the pic above from the SERPENT pool on EOL, I discovered several more...
Some further interesting feeding observations of Porania pulvillus, such as this one of it hunched over this rock and possibly feeding on the polychaete worm Pomatocerus sp. (which makes up the tubes). And of course, there could be hydroids or other encrusting goodies on there as well...
|EOL page link here SERPENT Media|
|From this EOL page working w/ SERPENT Media|
|From the EOL page here SERPENT Media|
|From EOL page by SERPENT media|
|From the EOL page SERPENT Media archive|
Bear in mind-if these things had been thought of as primarily suspension feeders for years and years-and it turns out they're big time predators??? That would represent a big shift in understanding the ecosystem/food web in this area. Sometimes it can all be in the details..
And there's MORE??
With my appetite teased I spread out a little more and went looking on Flickr!
Feeding on some green stuff! Algae? Hydroids? Image by Gordon.Milligan
Or maybe gettin' ready to go after those tunicates in the upper right hand corner?
Feeding? Or getting ready to spawn?
|Image by Mark Craig via Flickr|
Thanks to Jen Hammock, EOL, the SERPENT Media Project and all the photographers cited!
Thanks to this weeks' blog, a new mystery photograph from Diver/photographer George B, who sent me an image of this strange swelling on Porania pulvillus. Image was taken from the west coast of Scotland at 20 m depth.
Is it feeding and have a distended disk (as other starfish do here)? Does it have a parasite? Some kind of tumor? Not sure it has ever been reported before!!!
This is a neat highlight, that even though you have a species which has been recognized since 1776 and lives in the North Atlantic where many divers and scientists are active, many of these species remain poorly known.
It also highlights the value of crowd sourcing. Images on Flickr and YouTube add so many more eyes and observations...
|Images here from the Encyclopedia of Life|
I can't tell you how many times I've read something about starfish in pop culture or even in pop sci-and the writer assumes that starfish are the SAME all over the world! As if there was only one type.
This gets to be annoying..so let me just make sure everyone knows: There's a LOT OF DIFFERENT KINDS OF STARFISH. And they live in different places all around the world.
Similarly, I've talked about my field work in Antarctica and in the middle of my story, someone stops me to ask "Wait, there are starfish IN ANTARCTICA??"
So here are five things about the diversity of sea stars that will razzle your dazzle and make you a favorite at echinoderm-themed invertebrate zoology parties (esp. those where people are ignorant of starfish)!
1. How Many Starfish Species Are there?
here), but I assure you, that I am doing everything I can to kick that 1900 up a notch every chance I get!
Here's a post where I keep track of many of my new species!
More importantly, that's 1900 species in 36 FAMILIES. That means there's 36 different distinct groupings found all throughout the world in different habitats at different depths in different settings. So, its not just 1900 different kinds spread out all over the place- its 1900 species divided up into 36 distinct body types adapted to living in many different ecological niches!! (note that 1900 is a rounded figure due to questionable status for some names)
For those who need to know: the full list is in the PLOS paper listed above. So feel free to click and go!
Of the many weird kinds, there's Tremaster, as I discussed here awhile back..
the deep-sea brisingids! Crazy lookin' things that live in the deeps! Here
This Antarctic monster! Labidiaster annulatus! The Slime Stars! Yay Mucus!
Predatory Sun Stars! And just for good measure- here's a neat assortment from Hawaii!
2. Where Do Starfish Live?
All echinoderms, including sea stars, live in the ocean-on the sea bottoms (although their larvae swim in the water column). They are among the few groups of animals which live exclusively in marine habitats.
Starfish live in all the oceans! Atlantic! Pacific! Indian! Arctic! Southern!
And in answer to the question "Do starfish live in Antarctica?" and "Under the Ice?" Yes!
The video below is from the famous "brinicle" video released awhile back showing starfish (Odontaster validus, probably) getting around some hardcore Antarctic ice! (narrated by 30 Rock celebrity Alex Baldwin!)
Of the 36 living families of sea stars, nineteen of them occur exclusively in the deep-sea (436 species)! Four families are mostly deep sea but with some shallow-water members (1191 species) and several families include large numbers of deep-sea members. Only 8 families live ONLY in tropical habitats (218 species).
It turns out that MOST starfish live in cold-water (or temperate) settings, such as the deep-sea or in the polar or near polar regions!
So among those deep-sea starfish species, which ones live most deeply? As it turns out several starfish groups occur in the deep abyss below 5000 meters!
One of the most commonly encountered deep-sea asteroid groups at that depth is the Porcellanasteridae.
|Image from the EOL page|
3. Which Group of Sea Stars is Most Diverse? (i.e., Which one has the most species?)
What's weird about this question is that the group with the MOST number of species is probably the group you are least familiar with... Enter: The Goniasteridae!
Goniasterids vary in size and shape as you can see.. but some get REALLY large! Such as this monstrous Mariaster giganteus from Japan !! (held by my colleague Yoichi Kogure!)
Goniasterids are diverse-and there remain MANY different species yet to be discovered....They are ecologically important in deep-sea AND shallow waters.
I'll probably do a full post on this group at some point-but in the mean time here's a bunch so far!
Tosia-the biscuit star: hidden species and brooding behavior! here!
New genera and species of deep-sea corallivores! here! and some video!
4. How Many Undescribed Starfish Remain to be found?
|Image by Island_girl|
Sea stars/starfish are big, obvious creatures. One would think that we have found most of them...but you'd be wrong!
One subject group: The Goniasteride has 256 species in 65 genera. Out of the total # of genera and species: 14% (approx n=9) of genera and 12% (approx n=31) of species were discovered ONLY recently (since 2001).
I have further unpublished data on many MORE new goniasterids! Which suggests that the total number of newly discovered genera could go up to 37% and the number of new species could go up to 32%!!
These are rough estimates from one group. Most people might expect that new species would be found in inaccessible and poorly studied places such as the deep-sea or perhaps in distant tropical lands such as New Caledonia. But another possible source may already be right in front of us....
Cryptic species are those which are distinguished by genetics or reproductive differences, some other source of evidence OTHER than external morphological characteristics to demonstrate they are separate species. Molecular genetics shows great potential as a tool to discover diversity where cryptic species are concerned...
Again, the case of Tosia-the biscuit star: hidden species and brooding behavior! here! is a great example.
5. How Long Have We Observed Starfish in the Fossil Record?
|Hudsonaster USNM 40882, early asteroid from the Ordovician. Copyright Dan Blake. Image via www.tol.org/Asteroideahttp://tolweb.org/Asteroidea|
Some very early ancient forms (i.e., predecessors to modern day "proper" asteroids) are observed in the Paleozoic (540 to 250 million years ago!).
|Left to right: Trichasteropsis weissmanni (specs. MHI 843/1, SMNS 3173/5 and Noriaster barberoi (MPUM 8420) on far right. Images copyright Dan Blake, Images via www.tol.org/Asteroidea|
|Fr. Discovering Fossils UK|
|Image by Claire H|
|Fantastic image by Chelsea L. Wood|
And to the flatworm and parasitic worm people reading this? YES, I know flukes aren't free-living flatworms. It rhymed! So go with it for now. thanks for your patience!
Flatworms aka the Platyhelminths (in Greek-literally the "flat worms") look like living carpets. They are mostly predatory, but may also feed on small organic particles and live all over the place. They can be parasites, such as tapeworms or free-living beasts such as the one featured in the collage below.
These include the familiar Dugesia-that you find in high school biology (brown with arrow shaped head and two weird eyes) to these big, colorful species that live throughout the tropical Atlantic and Pacific. There are some 4500 recognized species of free-living flatworms..
|An awesome collage by Arthur Anker!|
another in Biological Bulletin 169: 182-198 (also by Shinn) and this one, from Canadian J. of Zoology 61(4): 750-760 which describes the species living in the sea cucumber
What's interesting about the ones that I'll be talking about is that none of these is exclusively parasitic (such as a tapeworm or a trematode). These are free-living species..but they live INSIDE the body cavities of echinoderms!
Think of it as if you ended up living in the intestine or the body cavity of a whale. Lots of space there and potentially...a lot of food. Plus protection from predators, the elements and a safe place to reproduce!
So, technically they aren't really parasites (where the host 'loses') they are commensals that are considered just kind of benign.
|Image from WallaWalla University Inverts site!|
It turns out that there's something in the neighborhood of SEVENTY species of different free-living flatworms that live in echinoderms as hosts! A nice list of these can be found in this paper here.
Most of these hosts appear to be sea cucumbers with sea urchins and sea stars. Some in cold water but also in the tropics! Crinoids and brittle stars seem to be among the minority as hosts for flatworms..probably because there's not much "living space" inside their body cavity. Or maybe they're just not as well studied?
Here are two well-documented worms from the North Pacific coast.. one that lives in several Pacific urchins and one in a North Pacific sea cucumber...
The Urchin as a "House" for flatworms!
Urchins on the west coast of North America (in the Pacific Northwest) include the well-known purple sea urchin (Strongylocentrotus purpuratus)
|Image by Joe McKenna|
|Image by Dan Hershman|
|Image by NOAA Photo Library|
|Image by Chelsea L. Wood|
|Image by Chelsea L. Wood|
|From the EOL page for S. dendrastrorum|
|Image by Patrick Warren|
|Image by Cheryl Moorehead|
What do they do in there?Mostly, these live in the intestine feeding on the host's intestinal lining (the tissue) AND apparently also like to eat on the symbiotic protists (the ciliates) that ALSO live in the intestine of the host. But this apparently doesn't create any detrimental effects on the host. So-commensal rather than parasitic.
Apparently, the worms produce egg capsules are released into the intestine of the host and released outside with the feces. When the capsules are eaten by a new host, they become active.... probably a reaction to the intestinal fluid and proceed to live out their new life in the new host's intestine.
Flukes in Cukes!
A free-living worm lives in the Pacific NW sea cucumber Parastichopus californicus.
|Image by T. Van Nunnery|
|Image by Chelsea L. Wood|
This species reaches the body cavity by penetrating the wall of the intestine..usually through the respiratory trees (feathery structures colored in blue in the pic). I've briefly mentioned this area as where some sea cucumbers can feed via their butt!
The eggs are spread out via the anus with the feces until they are devoured by a host.
|Image by Chelsea L. Wood|
So, there aren't a lot of records of flatworms that live in/among sea stars. Six were recorded in asteroids..and oddly enough, the one below was not included. So maybe its something new?
Description of this pic indicated the cold-temperate North Atlantic asteriid species Leptasterias littoralis. Is this a commensal flatworm moving within the tube foot groove? Moving around on the surface? Something new? A convergence of two species by chance?
|Image by Nick Sleptov|
Go to this pic of Echinaster callosus and look closely at the short, striped things crawling on the swellings! this one has a tighter shot that shows them a little more easily..note the brown squares with the white stripes.. (and includes a shrimp to boot!) WOO! Acoel flatworms?
How many remain to be discovered??
Today, here in Washington DC, we have an overcast day with a rather dreary storm raining down on us..and a quick skim through the news is filled with all kinds of blah and bad news, Sequester is the buzz of the town.. so..meh. What to do??
FLATWORM COLOR EXPLOSION!!!!!
A striking yellow/greenish Pseudoceros dimidiatus from Osprey Reef,Coral Sea.
|Photo by Richard Ling|
If you remember those funny arrow-headed ones that you could cut and via regeneration give it two or more heads? That was a flatworm! Many, many species are found throughout the world.
Free living flatworms are mostly predatory-feeding on immovable animals, such as tunicates to other smaller animals and worms. There's a LOT of different species with many interesting biological stories! Some (go here) are mimics with nudibranchs!
But most folks don't realize just how colorful and gorgeous they are in the tropics! Here is a bunch....
Pseudoceros bifurcus from Kenya.
|Photo by Jim Anderson|
|Photo by Wild Singapore|
|Photo by Arthur Anker|
|Photo by Pauline Bosserelle|
|Photo by "Jason" aka Jasdivr|
|Photo by Bill Stohler|
|Photo by Christian Loader|
|Photo by Chris Dow|
|Photo by Philippe Guillaume|
|Photo by Dyana Wu|
A neat one with a different texture! A "papillose flatworm" Thysanozoon/Acanthozoon? From Madang, Papua New Guinea.
|Photo by Arthur Anker|
|Another gorgeous pic by Arthur Anker|
|Photo by Eunice Khoo|
|Image by RJadams55|
And that in turn gives you insight into past events and other things around you. Cryptic? Yes..but I will explain.
This week's post is from Kurtis Hayne and A. Richard Palmer, University of Alberta in Edmonton
who have written a swell, new paper in the Journal of Experimental Biology 216: 1717-1725 (here)
(my thanks to Kurtis for an offprint of the paper).
It studies the reaction of the classic workhorse starfish Pisaster ochraceus as it reacts to one of the harshest of environmental stresses: the ocean itself! WAVES!! SPLOOSH!
|Image by Lance and Erin Willett|
Hayne and Palmer collected numerous individuals in and around Barkley Sound near the Bamfield Marine Sciences Center on Vancouver Island. Individuals were collected and measured to assess values for drag and lift. Some were tagged and returned to the field for various field transplant experiments (look below).
Specimens were also surveyed in the field and correlated with the power of various wave forces.
3. Sea stars were transplanted between sheltered sites to more wave-exposed sites revealing that they became LIGHTER per unit arm length, developing narrower arms after 3 months! There was a tight correlation between water flow and the body shape which strongly supported the idea that wave force was affecting the body shape.
The exposed form below is overall smaller in size, weigh less, and with a higher aspect ratio (arms narrower, etc.) and with a more dense skeleton.
1. This is thought to aid the individuals in a wave-exposed environment from being washed away. Not as much lift and not as much drag.
2. The heavier granules offer more protection against the crashing forces of the waves.
3. BUT, having a higher aspect ratio comes with some costs:
a. such as being more prone to overheating. Sheltered are much more effective at resisting
overheating and water loss. Although heating may be offset by cooling temperatures from
waves and such..
b. having smaller areas available for gonads. This results in lower overall production of
reproductive material and so on..
Image by jkenning
Image by Shannon Robalino
The protected body form
These make more sense in protected areas away from the harsh, crashing wave-swept regions:
1. Larger animals are more likely to be caught and washed out to shore. (greater drag and lift at play)
2. BUT the larger, thicker size involves more water retention and thus better thermoregulation and better cooling.
3. Greater volume for gonads! More potential offspring!
from Scenic Beach State Park in Washington
From Samantha Russell
Bear in mind-that in order to test these interpretations, animals were actually transplanted between protected vs. wave-swept areas. Transplanted animals (from protected to the exposed wave-swept areas) decreased in mass and increased in aspect ratio over time.
Environemntal factors directly affected the body shape of ochre stars!
Biophysics Meets old fashioned Taxonomy!
The great Stanford starfish biologist and Director of the Hopkins Marine lab, Walter K. Fisher identified several "forma" or distinct morphological variants of Pisaster ochraceus in his giant 3 volume monograph documenting and describing the asteroids of the Pacific Northwest from 1930.(sadly the Asteriidae is not in the volume linked).
It is difficult to escape the inference that the characteristic small spinelets of the abactinal area are correlated with queit water, but that this is ot the only factor is evidenced by the presence, along with confertus, of forma ochraceus and nodiferus, the latter found on open coasts and also in deep water (Monterey Bay).
Sometimes, these "forma" turn out to be distinct taxa-perhaps subspecies or species. But sometimes its just some variation in body form in reaction to the environment.
Just as if we took a flabby, couch potato from his comfy TV room with silk bedsheets and put that person into an underground mine to dig minerals for a living. We would perhaps see changes in musculature, bone structure, and maybe even hair/eye color.
So there you have it! A cool convergence between a modern biophysics story with a fun footnote from classical taxonomy/natural history!
Are these considerations we might apply to other intertidal asteroids in similar settings? (Stichaster australis from New Zealand). Image by Jon Mollivan
Want to know more about the Ochre Star: Pisaster ochraceus?
Here's my post about Pisaster ochraceus ecology and role in climate change.
and what explains all the color variation in Ochre Stars?? (here)
Want to see a sea urchin that lives in a high-energy wave swept environment? See Colobocentrotus! The Shingle Urchin.
|This fantastic image by Tyson Jerry from North Sulawesi|
Those pictures were close ups of asteroids from cold-water settings in the North Pacific & North Atlantic. There's a very different fauna of asteroids in those parts of the world compared to the tropics.
Most of the starfish in the tropical Indian and Pacific Oceans show a lot of granules, spination and armor and of course are composed of very different families of asteroids compared to those which live in the far North.
If you'd like to see some pics of the mouth armor in these types of starfish go here!
I start with the above : a STUNNING shot of Protoreaster nodosus, a commonly encountered sea star found throughout the Pacific. Shots below are macro shots showing skeletal features and colors of different tropical, Indo-Pacific starfish species.
More close up on Protoreaster with more pointed spines. Image by Nick Robertson Brown (Frogfish Photos)
What are these weird threads? Feeding tentacles from a benthic ctenophore? Gametes? Weird. Photo by MerMate (Eunice Khoo)
The strange soft-warty structures are a distinguishing feature on the surface of Echinaster callosus! Function unknown. Images by Optical Allusion
Some fantastic detail on the ophidiasterid Nardoa. Image by Stephane Bailliez
Here's a close up on Gomophia gomophia. Image by Okinawa Nature Photography (Shawn Miller)
An awesome close up of the disk on Fromia nodosa from the Maldives. Image by Philippe Guillaume.
Close up of Fromia indica. Image by Jesse Claggett
The papulae (aka the gills) and spines of Acanthaster planci-the Crown of Thorns starfish. Image by Barry Fackler.
another tight shot of a brittle star (Ophiothela?) living on the asteroid Nardoa. Image by deco4macro
Surface spines on Pentaceraster. The tiny white circles on the brown spaces are papulae aka the gills. Image by Friscodive.
The original NIWA press release is here. These urchins have been getting all sorts of keen press, includinghere in the N.Z. Herald and here in The Sun. And of here on New Zealand's Maori news..
and I thought.. EVERYONE needs to know more about these exciting urchins! and so today is a bit of a "refresher" on echinothurioid sea urchins!
I wrote a short summary about these for Deep Sea News several years ago...(here) and wrote a short bit about the commensal relationships between these urchins and fish here.
The quick summary version is:
|An Atlantic species by Hankplank|
|Image by Neptune Canada|
|Also by Neptune Canada|
Here's the spine close up showing the "walking tip"
|Image from the NIWA Benthic Inverts Facebook page|
|Image from SERPENT project here|
|From the NIWA page on this story|
For those who are not as keen on Scottish headwear, a "Tam o Shanter" is a cap, sort of like a beret (wikipedia here) and you can sort of see the resemblance.
|Image by DrHaggis|
|Image by H2omom.2006|
|Image by Neptune Canada!|
These were all discovered and described by looking at a variety of different characteristics. Some as straightforward as body color as well as spine shape and location. But some characteristics are more subtle. These are the individual pieces of pedicellariae-little claw like structures that are present on all sea urchins..which were studied using a Scanning Electron Microscope to yield distinct shapes...
|Fig. 28 from Anderson 2013|
|Figure 28 from Anderson 2013|
|Image by Aboireoujtulchien|
"Spiny" urchins are distinguished by the presence of an Anal Cone. See that white bulb on top? THAT is where the poop comes out! You don't see that in "proper" fire urchins as we'll be seeing.. Note also that the spines are much longer.
These urchins all belong to the genus Asthenosoma which includes six species spread throughout the Indo-Pacific region. Here's a neat video that gives you an idea of what they look like..
Yes, the colors are a huge shift in appearance, but similar to their deep-sea cousins, Asthenosoma also has the distinctive "walking" spines...
On this image of Asthenosoma varium the walking spines form a fringe around the lower oral side composed of distinctly yellow spines. My understanding is that most of these prefer soft, muddy bottoms.
|Image by Ben Naden|
|Image by NEPTUNE Canada|
But they remain venomous...
|Image by JianXu|
And if its not clear by now, YES. They're pretty damn venomous. My understanding is that its very painful.. but typically not lethal.
and they certainly do seem like they do, don't they??
|Image by Bruce Magun|
|Image by Daniel Stassen|
Close ups! showing some of the brillaint colors, spine patterns and etc.. I suspect most of these are Asthenosoma varium
|Image by MerMate|
|Image by Daphna130|
|Image by lupopeye|
|Image by maractwin|
|Image by Nick Hobgood|
|Image by B. Maither|
|Image by Russell Taylor|
From the Red Sea, Asthenosoma marisrubi with a more mellow look...
|Image by Key of Life|
|Image by Le Congre|
|Image by S1mon Mar5h|
|Image by Clark Chang|
|Image by Jesse Claggett|
|Image by Richard Barnett|
Urchin Riders from liquidguru on Vimeo.
Some of the little buggers actually "hollow" out a space, clearing out spines where they can live! You can see the bare patch on this one...
|Image by Klaus Stiefel|