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Articles on this Page
- 09/29/15--07:22: _Let's Learn About M...
- 10/07/15--07:40: _Some great Macro Sh...
- 10/13/15--06:18: _October 29th will b...
- 10/21/15--06:27: _Japanese Invertebra...
- 10/29/15--03:36: _Melibe Ghostly Nudi...
- 11/09/15--14:57: _Paris 2015: The Sta...
- 11/18/15--16:46: _Paris! Urchins in A...
- 11/30/15--22:28: _Imaging Brooding Br...
- 12/09/15--10:21: _What's up with dead...
- 12/24/15--06:50: _Happy Holidays! Pro...
- 12/30/15--06:16: _An Eventful Echinob...
- 01/13/16--08:40: _LyrocteisThe Imperi...
- 02/02/16--06:21: _What's New in Sea S...
- 02/10/16--11:58: _Heart Urchins! Burr...
- 02/23/16--19:16: _Zen of the Feeding ...
- 03/02/16--04:52: _Echinoderms with Sp...
- 03/09/16--05:28: _Purple invertebrate...
- 03/18/16--05:13: _Taxonomy Day 2016! ...
- 03/30/16--11:52: _Natural History Art...
- 04/05/16--21:46: _Crinoid Fossil Fore...
- 09/29/15--07:22: Let's Learn About Multi-armed OPHIUROIDS!
- 10/07/15--07:40: Some great Macro Shots of shallow-water Tropical Urchins!
- 10/13/15--06:18: October 29th will be #SEASLUG DAY!!
- 10/29/15--03:36: Melibe Ghostly Nudibranchs for Halloween! Happy #SeaSlugDay 2015
- 11/09/15--14:57: Paris 2015: The Starfish Mouth in Abstract
- 11/18/15--16:46: Paris! Urchins in Abstract!
- 11/30/15--22:28: Imaging Brooding Brittle Stars Babies!
- 12/09/15--10:21: What's up with dead starfish washed up on beaches?
- In almost EVERY instance that this has been reported, there have been reports of either storms or high winds. Even if this was not necessarily reported in the news report itself. For example in the case of the Queensland Pentaceraster case, there was a reported storm involving hail the day before!(here)
- Bear in mind that storms don't JUST mean high winds and rough water current. It also means FRESH WATER input. Echinoderms are notoriously intolerant of low salinity/freshwater. Low salinity water might serve to weaken or otherwise just disable enough of them to be washed ashore.
- The species in question: Luidia clathrata, Pentaceraster sp., Asterias forbesi, Asterias rubens etc. (and others) are all known to occur on sandy or unconsolidated (i.e. loose sand) sediment bottoms. So its not unreasonable to see how strong water currents associated with inclement weather could serve to pick them up and drop them ashore. These species all tend to occur with rather high abundance so they tend to end up washed ashore in great numbers.
- 12/30/15--06:16: An Eventful Echinoblog in 2015! #Recap!
- 01/13/16--08:40: LyrocteisThe Imperial Harp Shaped Comb Jelly!
- 02/02/16--06:21: What's New in Sea Star Wasting Disease?
- They are now more obvious because the adults are gone (and we are looking)
- They have become more bold because the adults are gone.
- Are there more of them present now because of absent adults?
- How fast do they grow? Will they enter in the former adults ecological setting?
- 02/10/16--11:58: Heart Urchins! Burrowing their way into your Valentine's Day!
- 02/23/16--19:16: Zen of the Feeding Sea Cucumber
- 03/02/16--04:52: Echinoderms with Spines for Walkin'
- 03/09/16--05:28: Purple invertebrates in the Abyss!
- 03/18/16--05:13: Taxonomy Day 2016! Museum Collections are the Taxonomist Habitat!
- Identifying economically important pests or invasive species
- Long term environmental monitoring (such as this one in the Gulf of Mexico)
- Identifying species used in medical research
- Identifying species with direct economic importance (i.e. corals or shells for jewelry)
- Geochemical analysis to study past environments
- Identify toxic/poisonous/venomous species
- Identifying bird feathers involved in airplane accidents
- and of COURSE my favorite application of museum research collections: Identifying weird bugs from a crime scene to help locate a murderer!
- 03/30/16--11:52: Natural History Art Spotlight: John Meszaros & Nocturnal Sea!
- 04/05/16--21:46: Crinoid Fossil Forest Revisited!
I've often talked of my love of multi-armed sea stars. BUT brittle stars can have more than five rays (arms) also!!
So wait, there are ophiuroids (brittle stars, basket stars, etc.) that have MORE than 5 rays??
Most sea stars (close relatives to ophiuroids) have 5 rays, but a significant number of them have more than five rays and there are some entire groups of sea stars (e.g., the Brisingida) which are characterized by having multiple arms (six to 20ish). When sea stars have more than 5 rays there tend to be about 7 to 15 of them. But some, such as the Antarctic Labidiaster can have up to 50.
What one sees in most starfish species is that multi-armed sea stars tend to be large, highly mobile and predatory. This tropical, shallow water Luidia maculata for example demonstrates all of those qualities.
Generally none with intermediate arm numbers (i.e., 8 to 9) and no species are known with more than 12 rays.
(My thanks to Dr. Sabine Stohr for assistance with names!)
Most brittle stars have 5 rays. Having more, implies that the extra arms are somehow adaptive or suggest that the added investment to develop one further body part is somehow consistent with the life mode of the animal. Most ophiuroids appear to have a much more invested skeleton compared to asteroids, so it would seem that adding more arms is much more of an investment in development,
Low numbered multi-rayed brittle star species, those with about six to eight arms are not uncommon and seem to show a fairly diverse range of habitats. But the ones with more than 10 rays are more seldom seen.
This one for example is Ophiothela danae. 6 rays. These occur in tropical-shallow water habitats and live with their arms wrapped around the stalks of sea fans and sea whips. Does the sixth arm help facilitate this lifestyle??
This species appears to be successful. It occurs widely in the tropics and has "invaded" the tropical Atlantic from the Pacific.
Here is Ophiactis savignyi, a brittle star that reproduces both sexually and asexually (i.e. it divides in half) brittle star which occurs globally all around the world (read more here). Perhaps its sixth arm is part of the asexual condition? Or maybe its cryptic life style?
Here is Ophionotus hexactis. Six arms. Adaptive? Predatory? Highly Mobile? An animal I'm not sure much is known about it.
But on the OTHER hand, here are some Antarctic brittle stars, such as Ophiacantha vivipara which have SEVEN arms. Its a brooding species (i.e., the adults raise babies on their bodies). Not sure how this benefits the animal. Maybe in feeding? Aids in parental care somehow? Or maybe its just an incidental feature?
From Antarctic ophiuroid blog https://brittlestars.wordpress.com/2010/01/27/some-peculiarities-of-the-antarctic-ophiuroids/
There are a few more species of ophiuroids that show six to seven arms than I've shown here. But for various reasons (i.e, I either didn't have pictures of them, space, etc) I haven't included them. Several species of serpent stars in the genus Asteromorpha for example can demonstrate six or seven arms.
Species with more than 10 arms
Ophiacantha enneactis & O. decaactis. The genus Ophiacantha, is kind of unusual because it includes several species which possess more than 5 arms (see O. vivipara above).
Two of them, O. enneactis (illustration-top) and O. decaactis (below) have been collected from the Aleutian Islands in deep-water. O. enneactis is from 549-881 m. And O. decaactis is from comparable depths.
These are similar species and both are pretty small. What they do down there in the deeps with all their arms is "poorly understood." (i.e. we don't know). Perhaps suspension feeding? Predation?
Belyaev & Litvinova 1976
|Image from Belyaev & Litvinova 1976|
I thought Basket Stars already had more than five arms??
Basket stars are a subdivision of ophiuroids called the Euryalida. They tend to have big, thick arms with fleshy tissue covering over their skeleton. These ophiuroids extend their arms into the water column and usually have hooks or long arms to feed on food or prey as it swims by..
I've written about one particular basket star, Gorgonocephalus here. But there are a fair number of basket stars in cold water and tropical habitats.
Note that although there seem to be many arms, there are in fact ONLY five. But they branch...
Below is the underside of Gorgonocephalus, the cold-water basket star from the Arctic/subArctic. Note that only five rays radiate away from its mouth. The arms bifurcate or split for several iterations away from the five primary rays on the disk..
That's what makes A. sol, so unusual. It actually has 10 to 11 arms!! Making it the ophiuroid (not technically a "brittle star") with the MOST number of arms!
Its species name "sol" refers to sun, which likely alludes to its arms radiating away from the mouth.
This species occurs in the Antarctic in fairly deep depths 300-1200 meters. It was described by the famous echinoderm taxonomist/biologist Theodor Mortensen in 1936 in his HMS Discovery monograph. We apparently don't know much about its biology aside from the fact that its a brooding species and tightly hugs its substrate...
|Image by Igor Smirnov via WoRMS|
|Hypselodoris zephyra image by Steve Childs via Wikipedia|
Let it be announced herein that October 29th of this year (Thursday) will be SEA SLUG DAY!! #seaslugday
So, why "sea slug" and not "nudibranch"? We're going to be focused primarily on nudibranchs, but there's actually a lot of different type of "sea slugs" which many people mistake for nudibranchs or which often get lumped in with them. A brief summary on these relationships are nicely written up on the Wikipedia page.
Sea hares for example are actually a distinct group from nudibranchs. But they are often regarded as "close" to nudibranchs.
So, to avoid "nudibranch VS. sea hare" or "nudibranch VS. sacoglossan"arguments and etc. I'm just going with "sea slug". For the biologists out there: No, its not monophyletic. But its an easy catchall term. and the hashtag is slightly shorter than "nudibranchday".
Why October 29th for Nudibranch Day?
Nudibranch Day honors Dr. Terry Gosliner! Biologist at the California Academy of Sciences and one of the world's pre-eminent experts on nudibranchs!! Go here to see more about him October 29th is his birthday!
Terry also coined the popular term "Bobbit Worm" for the raptorial polychaete Eunice sp. (many are E. aphroditois).
Why have a Nudibranch Day? Because they are fantastic animals and I just thought it was just LONG overdue. So I'm just doing it. To be honest, there was an earlier attempt at "nudibranch week" here. But frankly, other than "during Shark Week" there's no fixed date indicated. Its also not my style to honor something by holding it up a contrarian force to something else. Positivity!!
We also have Halloween that weekend! I wouldn't mind at all if it extended out to Friday or even the weekend! To 'branch out as it were!! (ha!)
What better time to celebrate nudibranch diversity???
trong interest in Japanese science fiction and pop culture. One of my starfish has even been made into a toy!
My research over the last few years has taken me not only to Japan but also gotten me interested in the nomenclature of various Japanese starfish species!!
Although many of these are essentially common names, they are surprisingly standardized and are widely recognized in addition to the western Latin names. While studying these I also encountered a few other cool stories about invertebrates which have been part of Japanese folklore and myth.
So this week: The Invertebrate-Japanese folklore connection! Names & monsters/spirits inspired by invertebrates!!
I thank Matt Alt of AltJapan and Dr. Toshihiko Fujita of the National Museum of Nature & Science for providing me with some of the the information in today's post!
1. The Oni Hitode
So, the termyokai (妖怪) refers to a spirit or ghost , most of which have a strong root in Japanese folklore and myth. There are a great MANY types, some of which are listed here and Wikipedia of course! Perhaps one of the types of yokai which I see popularly presented in pop culture and literature and in some Western sources is a demon called an Oni, of which one face is represented below...
Here's another kawaii I found of the Oni-hitode, which from what I understand was part of a"Kill the crown of thorn starfish" campaign. Acanthaster planci, is a fairly well known predator of coral and has been undergoing massive population booms leading to frequent efforts to remove them.
|From this Japanese site|
2. Higuruma Hitode (or not?)
Another cool Japanese starfish name is one this deep-sea brisingid starfish, Brisingaster robillardi.
I've described brisingid sea stars at length here. Deep-sea species which feed on prey in water currents using "velcro" (tiny claws) on their spines. More great images of these animals here.
The common name for this species is called the Higuruma Hitode which sounds GREAT! Hitode is Japanese for starfish. But What is a "Higuruma"??
Higuruma is apparently one name for a ghost/yokai called Kasha (whose name apparently translates to "flaming chariot" who carts the corpses of sinners off to the underworld (thanks to Matt Alt for this info). I suppose in this case the "corpses of sinners" are represented by small crustacean prey! Muahaha!
The resemblance between the flames (the arms) emerging from the wheel (the disk) is how this starfish was likely named! Pretty neat!
|Image from Dr. Fujita|
|Image via the Yokai Attack! FB group|
3. The Sazae-oni aka the "Snail Ogre" 栄螺鬼
This yokai is apparently one of the more malevolent ones and according to Yokai.com is a dangerous spirt that pretends to be a beautiful drowning woman in order to lure and feed on sailors.
There's a whole mythology about these yokai which involves pirates and monsters biting off their testicles. You can read the colorful version here.
|Image by Toriyama Sekien via wikipedia and also this Japanese site|
This species of snail is widely familiar to the Japanese and was even made into a kaiju called Gogo in the show Ultra Q, the precursor to Ultraman!
4. Hekigani ヘイケガニ The "samurai crabs"(the crab Heikeopsis japonica)
This "ghost" is actually more of a ghost story. It basically relates the story of this crab, Hekeopsis japonica which often have a very human-like face on their carapace (i.e., the top side of the skeleton).
warriors defeated at the Battle of Dan-no-ura as told in The Tale of the Heike. Wikipedia has a nice summary of this event.
But here's a gorgeous painting which shows this event in various stages..
|Image by Utagawa Kuniyoshi via Wikipedia|
4a. The Kani-Oni: DEMON CRAB!!
While doing research for this post I came across this creature, the Kani oni! aka the Crab Demon. I couldn't find out much about it, but I did realize one thing..
So this particular ghost isn't actually based on an invertebrate..but it gets honorable mention..
The name Umibozu translates to "Ocean or Sea, Buddhist Monk" and have been explained as the ghosts of drowned buddhist monks. They are apparently haunted spirits of the ocean and mentioning their name invokes bad luck for ships at sea.
|Image photographed by Martin Buschenreithner. Borrowed from the US Slug Site!|
Given its proximity to Halloween and my propensity for sharing cool stuff about weird animals my post this week is about one of my favorite bizarre sea slugs: The ones in the genus Melibe!
Melibe (in the family Tethyiidae) includes 17 currently recognized species which are known Primarily from the tropical and temperate Pacific but with a minority of species from the Atlantic, including South Africa and the tropical west Atlantic (Bahamas, Florida, etc.)
Personal caveat: I am not an expert in nudibranchs and have gone with names used by the photographers. If you know better let me know and I will correct them.
This species is fairly well known. With nice brief write up by Monterey Bay Aquarium but many others as well.
A close up on the lobes on the body reveals these fine branching structures-the digestive glands! Which function in digestion of food
What happens when you take these digestive glands to the extreme? Along with a transparent body?
You get Melibe colemani, aka the "Phantom Melibe!" named for the photographer Neville Coleman, who was a noteworthy photographer, diver and natural historian from Australia.
Most of the species seem to crawl around or stay in one place, but given the motivation, some species can swim.. Here's what I think is Melibe viridis, based on this article in the Sea Slug Forum but kind of swimming in the water column..(identified as Melibe japonica, since synonymized)
Melibe diversity is fairly mind boggling.
This one from Lembeh, Indonesia. This one is also identified as Melibe viridis, but which seems to vary somewhat from the one from Japan. These can get quite large with some individuals reaching almost a foot long!
There's a nice write up on Melibe viridis here on the Slug Site. Here.
Melibe engeli from the Philippines
Bonjour and Greetings! My apologies for missing a post last week! I am currently on a research visit at the world famous Museum national d'Histoire naturelle in Paris! Between jet lag and getting my work set up, things got away from me!
Here is a collection of close ups and abstracts from echinoderms in the Tokyo Museum.
Spines serve a protective function in many species but are also part of how the animal feeds. The full range of how these structures function is not clear. In contrast, other mouths are surrounded by granules or plates presenting a somewhat different interpretation.
but certainly.. these might even evoke more artistic interpretations from others!
Euretaster, a tropical slime star. Spines galore!
Last week was all about starfish mouths & their spines, etc.
I've blogged before about sea urchins from Paris. Here's one...
and an older one..
And a similar type of blog from my visit to the natural history museum in Tokyo!
Oral spines on this cidaroid urchin. Yikes!
t presented in GigaScience by some colleagues at CapeTown University in South Africa whom I met while I was visiting a few months ago!! Jannes Landschoff, Anton duPlessis and Charlie Griffiths.
Their study actually surveys THREE species of brooding brittle stars!
What does this mean? In MOST echinoderms, following fertilization juveniles pretty much settle out on their own and are left to grow/rear out on their own. But in some unusual instances there is actually parental care!
So, yes, some adult echinoderms rear juveniles! Yes! Baby echinoderms! I've detailed this behavior in starfish in some detail here. and of course, who can forget the life and death struggle of tiny asterinid starfish hermaphrodites who attack and eat one another in the "womb" of the mother?? (here)
Jannes' study focuses primarily on three brooding species in the South African area, including Amphiura capensis, Amphipholis squamata (both in the Amphiuridae) and one called Ophioderma wahlbergii
Jannes' work was actually surveyed here in GigaScience's own blog Jannes and co authors use three dimensional visualization tools, including x-ray micro tomography scans to unobtrusively visualize brooding juveniles without destructively sampling the original specimen. Neato!
This gives you an idea of what Amphiura capensis looks like..
|Image borrowed from Eastern Cape SCUBA diving! Go check em' out!|
Asterias forbesi from South Carolina via http://wbtw.com/2015/02/10/1000s-of-starfish-wash-ashore-on-sc-island/
So, for whatever reason, I've been noticing an uptick in the number of reports (and questions from the public) about moribund or otherwise dead starfishes (aka sea stars) being washed up on beaches en masse.
And I've seen a host of different reports. Many from the southeast coast of the United States, in the United Kingdom and even from Cape Town, South Africa.
I thought I would take a moment to provide what seems to be the MOST likely explanation: During storms, violent or strong water currents pick starfish up off soft sediment bottoms and wash them ashore.
Different species of starfish in different parts of the world are affected but all share certain commonalities.
|Image taken by Jan Mees. From the World Registry of Marine Species|
This is a shallow-water tropical species known primarily from the western Indian Ocean, especially on the east African coast. The species descriptor "lincki" is named for the German naturalist Johann Heinrich Linck, the author of a noted monograph on sea stars, De stellis marinis liber singularis published in 1733. Johann Linck is also the namesake of the familiar starfish genus Linckia. Many years ago I wrote a little bit about where funky starfish names come from before, especially Nardoa and Luidia.
Image taken by Adrian Pingstone 2005 at Bristol Zoo Aquarium, Bristol, England via Wikipedia|
The spines on this species and other oreasterid starfish likely serve against larger predators. Its unclear if they are effective against smaller specialized echinoderm predators such as these harlequin shrimp
Variation! The skeletal patterns on these sea stars are broadly consistent and distinctive for this species. But in the same way that people can have different hair and skin color, different facial features, etc. starfish show variation in spination, pattern and even color...
Here are some examples. Its unclear if the differences are simply random or if they correspond to some kind of environmental factor such as food, etc.
Tanzania, African coast.
Tanzania, African coast
Zanzibar, African coast
and the occasional 6 armed variant..
As with the Indo-Pacific species, P. nodosus, this species is fished for the tourist trade. Data about its reproductive abilities and "carrying capacity" for a fishery aren't well documented.
ART! For some odd reason, this species has also served as the inspiration for many distinct types of art. This postage stamp...for Mozambique in 1982 and the more recent rendition below it, including the pastel and of course TATTOOS!
starfish tattoo by SunofKyuss on DeviantArt
Happy Holidays from the Echinoblog!
One of my most memorable trips was from April-May when I visited the Iziko Museum in Cape Town, South Africa!! Thanks to a collaboration with Dr. Lara Atkinson from their marine environmental organization, SAEON (the South African Environmental Observation Network) I was able to visit their marine invertebrates collection and study the collections.
Stalked crinoids, benthic ctenophores and enormous sponges! (go here)
|Picture by Robert F. Bolland from the Okinawa Slug site|
During this visit, Curator Bart Shepherd, a colleague of many years from our days at Steinhart Aquarium indulged me in showing off this recent collection from the Academy's scientific expedition to the Philippines: the benthic ctenophore Lyrocteis! Possibly Lyrocteis imperatoris..
Here's the species we saw in the Hawaiian Islands during the Okeanos Explorer cruises in September. In theory.. there are only two species.. the Antarctic one and the tropical Pacific species.
Its possible (and even likely) that there is more diversity (i.e., more species) but the animals don't make it easy to study them.
Why? Because they aren't seen frequently and when they do, collecting is difficult. The individuals
aren't easy to sample and for whatever reasons, the body of these animals is extremely difficult to preserve..so intact specimens aren't generally available to study...
Here were some spectacular red ones from Okinawa..
— Bart Shepherd (@SteinhartBart) May 1, 2015
— SeaKeys (@SeaKeysSA) August 22, 2014
One of the nice things about our modern age is that video and image observations have become easy and of high quality
If you have Facebook, here's a feeding video of the Lyrocteis collected by Steinhart Aquarium from the Philippines..
Here's a nice one of a Japanese species with tentacles extended... from SHINKAYABLOG which translates to "deepsea" blog This is basically similar to the way that swimming comb jellies feed...
|from @deepsealife https://twitter.com/deepsealife/status/605369053209755648|
今回このようなマグネット物も作りました。オオグチボヤとコトクラゲなど pic.twitter.com/cc5hLD16vr— 紀ゐ@デコトコノマ展 (@yu_kiz) September 10, 2013
Dr. Komai, in his 1941 description of this species recounts an interesting story about "when" this species was discovered. Because apparently, although he described it in 1941.. he was NOT the first one to have encountered it!!
What makes the story of the discovery of this remarkable ctenophore more interesting is the fact that another specimen of evidently this form had been obtained previously from the same Sagami Bay and recorded by a Japanese zoologist, but without any idea of its real nature....
...in August, 1896, we find a short note in Japanese by T. N. (obviously Tokichi Nishikawa, the inventor of the famous cultured pearl) entitled " A curious animal" with rather good illustrations, one of which is reproduced in Fig. 3. The accounts and figures clearly show that the 'curious animal' was no other than a specimen of the present platyctenid.
" Nobody who saw The real nature of this form clear forty-five years later. T. Komai. it could tell at that time what thus remained enigmatic only to be made clear forty-five years later."..and don't worry, I haven't given up echinoderms! But travelling makes you appreciate opportunistic topics!!
|image by Jonathan Martin|
So about two weeks ago I was in Seattle at the Sea Star Wasting Summit, hosted by the Seattle Aquarium!
This was an informal gathering of about 35-40 people who work on the west coast of North America, ranging from Alaska to Southern California to report on various aspects of Sea Star Wasting Disease (aka Starfish Wasting Disease aka Starfish/Seastar Wasting Syndrome).
What do we know?
1. Who? The disease seems to affect sea stars in the family Asteriidae most acutely. This includes Pycnopodia helianthoides (aka sunflower star), Pisaster spp (esp. P. ochraceus-the Ochre star), Evasterias troscheli (mottled stars) and Orthasterias koehleri (rainbow stars). Pycnopodia helianthoides, the sunflower star seems to have been one of the hardest hit...
but ultimately the disease seems to affect nearly every shallow-water seastar species on the Pacific west coast. So that includes leather stars (Dermasterias), Bat stars (Patiria), sun stars (Solaster) and so on...
There were a few species which showed much lower incidence of being infected but its unclear if that's simply an artefact (i.e. they aren't seen that often to begin with), less vulnerable, but there is really no further data...
|Image from this article in Vice: http://www.vice.com/read/the-wasting-0000650-v22n5|
|map from http://data.piscoweb.org/marine1/seastardisease.html|
There is another "die off" event on the east coast but it has not been as thoroughly evaluated, so not sure. This 2012/2013 blog by Elena Suglia documents some of this phenomena
|image by Allison Gong|
This is will likely be important in piecing together the actual cause of how the disease actually kills the sea stars, which remains poorly understood.
Challenges: figuring out what causes the disease is difficult and remains elusive.
So, by now many people have likely seen Ian Hewson et al.'s (2015) article showing identification of the Sea Star associated Densovirus (SSaDV) with the disease. Popularly reported here and in other news outlets..
This was an important first step. But its important to realize that we still do NOT KNOW that this is the actual CAUSE of the disease.
Probably one of the most important lessons I picked up from the meeting was how careful the work of disease pathologists needs to be.
Correlation is NOT Causation!
Powerful genetic tools have allowed us to characterize the SSaDV virus and experiments show that it is ASSOCIATED with the disease. But we have yet to identify exactly HOW Starfish Wasting Disease actually works. In other words, what actually happens to the animal to initiate death?
Just because we have this "disease associate" does not actually mean that it causes the disease.. it could simply be present with the disease as part of the suite of entities (e.g., bacteria, protists, etc.) taking advantage of the sick animals. Or it could be something already present that has become fouled or modified by some other factor.
My take away message was that MULTIPLE lines of evidence (genetics, tissue analysis, external observations, etc.) should all converge on the same conclusion. In other cases, pathologists are able to actually observe the agent (virus, bacteria, etc.) perform whatever action it takes to create the disease and thus the symptoms..
At this point, we are still working on what actually causes the "wasting symptoms" to occur. This is not to say we are clueless about it..but a definitive cause has not been shown.
One of the biggest issues we have right now? Understanding starfish biology.
A LOT of the study of invertebrate physiology went "out of style" in the 1960s along with a bunch of natural history research. There are many instances when we just don't understand what "normal" is for sea stars (or their relatives for that matter).
And so..the other powerful tool at play? Careful critical thinking..
(and yes.. what this means in the real world is that NO zombie or science fiction disease movie is likely EVER going to be solved in two hours!!)
What Tools are being used?
So now that I just got done saying a whole bunch of stuff about care and critical thinking, that is NOT to say that scientists are not throwing a whole arsenal of scientific tools at this problem to try and obtain as many different types of data as they can!
Dr. Felicia Nutter and student Eric Littman at Cornell University for example utilized sophisticated imaging techniques ranging from traditional X-rays to CT scans in order to look at the endoskeleton in afflicted sea stars, which it was thought, might be showing decreased skeletal density.
|Image from http://phys.org/news/2016-01-imaging-technology-combat-disease-endangers.html|
But as mentioned above, all roads should lead to Rome.. and with any luck, the results from these studies should all be consistent with one another...
Are there/Will there be Ecological Effects??
So, although a LOT of the attention both public and scientific is on the disease itself, many folks often forget that the after effects of the disease will also be very significant!
Sea stars such as Pisaster ochraceus and Pycnopodia helianthoides occupy very important roles in marine ecosystems. Called keystone species, their presence and/or absence as predators is thought to have a HUGE effect on the organisms around them.. (I wrote up a little of this on Pisasterhere)
So what happens when those predators are suddenly gone??
This one for example, allege that there has definitely been a shift in abundance of prey species..such as sea urchins as mussels.
That basically means that the loss of a predator triggers an increase in prey (here was an earlier blog post about urchin barrens).
Some scientific observations suggest that we might be seeing some of this.. but not necessarily everywhere. Environments across the coast vary.... so what you see in some parts of California might NOT be the same situation in some protected cover in Oregon....
Time, further data and experiments will tell..
1. Are all the starfish on the coast extinct? Is my favorite species (e.g., Pycnopida, Pisaster, etc.) extinct??
In NO instance is ANY of the species surveyed thought to be completely extinct. Some individuals and news agencies have either misreported or exaggerated the the impact of the disease. MANY populations have been decimated. Localized populations have been wiped out...but there STILL are healthy populations of all afflicted sea stars species.
So, some species are "locally extinct" which means that you might not see any at your favorite local rock pool or pier but there's no evidence for complete and total extinction.
2. What about the juveniles we are seeing?
There are many reports (such as this one in Nat Geo and this one in the OregonLive) of smaller individuals of various species, Pisaster, Pycnopodia, etc. being seen widely along the west coast where adult starfishes have been wiped out by SSWD.
There were MANY reports of these out in the intertidal zones along the coast. The significance of the juveniles is unclear at this point. Possible reasons and questions as to why we are seeing them:
If you see any, you can report them to the Seastar Wasting Website here.
You can download a nifty GUIDE to identifying tiny juvenile sea stars HERE.
3. Is the worst over?
Yes. It seems to be, but mainly because most of the adults which carried the disease are themselves all gone. Its unclear what factors are at play insofar as why some populations have been more heavily hit than others.
4. Do Any of the standard aquarium antibiotics work?
Many of the standard aquarium drugs (antibiotics, etc.) seem to be most effective against the secondary bacterial infections which attack the animals after becoming sick. But unfortunately, they don't seem to curtail the actual disease much if at all.
5. Is Climate Change/Temperature a factor?
I would say yes. And others would agree with me (here). There have been several informal experiments and observations of seasonality which suggest that higher water temperature is, at least, significant and worth investigating as a factor. But, at the time of this writing, a clear paper has not been published which establishes a rigorous link.
6. Is the wasting disease caused by Fukushima/Republicans/Democrats/Cthulhu/Extraterrestrials/ Atlantis/Inner dimensional beings from the 7th Parallel?
Nope. Not even a little.
My thanks to Lesanna Lahner, Ian Hewson, Melissa Miner and the other participants at the Sea Star Wasting Symposium!
Standard caveat: i've done my best to represent a LOT of information. Any mistakes are my own.
The Sea Star Wasting Site at UCSC:
Ian Hewson's blog about SeaStar Microbial Ecology: https://seastarwastingdisease.wordpress.com/
iNaturalist: Tracking Sea Star Wasting Disease:
A useful summary page from Sanctuary Integrated Monitoring Network (SIMoN)
Heart urchins are in fact what's called "irregular urchins", a subgroup known as spatangoids.. These are sea urchins which DIG into sediments. They are closely related to sand dollars (both of them are considered "irregular urchins"). I've discussed this in detail here. Spines and jaws in these animals are specific adaptations for this life mode.
I've actually written about one of the better known heart urchins, Echinocardiumhere. Note the name of that genus, Echinocardium which breaks down into its root words Echino for "spiny" and -cardium for "heart."
As I've discussed elsewhere, heart urchins live primarily in sandy or sediment-type bottoms. They occur widely around the world and although most people don't immediately recognize them, they are pretty diverse, about 18 families with many, MANY living species and even more fossils...
They even go by many, many colorful common names "sea potato", "sea eggs", "sea hedgehogs", etc.
When people think of sea urchins, they usually think "spiny ball" and heart urchins are no different! BUT they have urchins that are modified as part of their life style to burrowing/digging through sediment..(as we'll see)
SOME species, such as this Lovenia (top) and the Eurypatagus(?) below have very long and pointy spines most of which you'll notice, are all directed backwards. They would otherwise seem rather ungainly for digging..but these live in shallow-water habitats and the spines, sort of akin to those of a porcupine, seem to aid the animal as defenses...
But the spines can also be used to aid in movement and these urchins move quickly when they want to...
5. They Dig into and eat sediment!
Let's face it, heart urchins are frakkin' adorable. They look like little underwater moles! Here's a nice cartoon of how they live.. basically they love being buried under the sediment/sand and stick their tube feet up out of the top to respire and so forth..
|From Nichols 1959|
4. Bioturbation is important
You don't often SEE heart urchins that often, but that doesn't mean they are unimportant. They are fairly significant bioturbators! i.e. animals that dig through, aerate and mix up the sediment!
NIWA's Drew Lohrer wrote this really nice summary(2003) of the importance of the heart urchin Echinocardium and their primary impact: bioturbation.
Basically, animals that live in sediment, DIG. And their digging imparts an important biological impact: This distributes nutrients, mixes up the sediment allowing oxygen to be transported around, basically leaving the sediment in a place where OTHER animals would be able to use it.
Here's is Lohrer's simple but lovely diagram showing how this works...
As a result of the heart urchin habitat (being buried or mostly so), their skeletons are favorably inclined to be buried and preserved as fossils.
So, you want to know how animals with "academic interest" have a practical use?? Well, as it turns out Japanese heart urchins, including Spatangus leutkeni, Brisaster latifrons and Echinocardium cordatum were among three species used as indicator species to detect Cesium in and around Fukushima!
These were only a few indicator species of course, the others including sea cucumbers and polychaete worms. BUT these are all part of the infauna..that is the animals which live in the sediment and digest the organic materials from the mud and so forth.
Many infaunal echinoderms were used as part of this, apparently as yet, unpublished study...
Extra! REPRODUCTION! Massive aggregations & spawning video!
And of course, there's SEX. I wrote, wonderingly, about the massive reproductive aggregations of Maretiahere. I still don't know much more about it.
Here's a cool video of a heart urchin from Bonaire. So on that note, Happy Valentine's Day if that's your jazz...
Sea cucumbers are versatile creatures. Some species can actually feed with filter feeding apparatus inside their anus (shown below). If you're not feeding from the front there's always the other end...
it turns out that this serves a vital function to ecosystems in both shallow and deep-sea ecosystems (see the secrets of sea cucumber poop here! ) Sediment is aerated and "turned over" and doesn't just build up anoxic organics... etc.
here is where it all starts!
Some nice video of a Japanese species showing aforementioned feeding tentacles which are used to pick food off the substratum
Lembeh Magnum Sea Cucumber from liquidguru on Vimeo.
Sunday, the ROV spied this awesome beast, a weird sea urchin in the genus Aspidodiadema. Although there's at least one species known in this area, A. hawaiiensis, I'm not sure that this is the same thing.
I've talked about this urchin before. The spines bow out from the central body and touch the bottom rather than simply projecting outward as they do in other species. They are unusual in that they use their spines to "walk" along the sea bottom.
Here's a diagram of another species but with the "walking tips" clearly deployed on the bottom
On Sunday, they spied ANOTHER Aspidodiadema sp. But the video actually captured the unusual TIPS of the walking spines!!!
Look at the red arrows below pointing to the "walking cups" on the spines that the urchin uses to move!
Think of the spines like the long legs on the spider robot from Johnny Quest!
This all makes sense though. Spines are how these animals interact with their environment. In these deep-sea habitats where you have a lot of water currents and unstable bottoms, these spines help them. Either as support or to help move efficiently where a soft tube foot might not.
Weird. But I love figuring out strange sh*t like this!!
One thing I noticed while reviewing the recent dives and those from last year was just how much COLOR you see in the deep-sea.. black, white, ORANGE... and purple!
Purple is of course, the color of kings! In Chinese painting, purple represents the harmony of the universe because it mixes red and blue. There's a whole bunch of meaning which you can find on Wikipedia..
Functional explanations for animals with black, white (such as this Henricia) or transparent/translucent body walls seem to be explained pretty readily by light-related/lack of pigment type explanations.
1. There's this big echinothuriid urchin, Tromikosoma As discussed last week, these walk around on the deep-sea floor with spines modified into walking legs.
The shallow water relatives of these urchins are VERY poisonous and brilliantly colorful! As presented here, a few years ago.
Curiously, another purple echinoderm is this feather star (crinoid), Sarametra triserialis (Zenometridae) as ID by Chuck Messing.
As has been mentioned before, these are big blobby pillow shaped starfish that emit a noxious mucus when annoyed..
AND this handsome soft coral, Clavularia!
So, I don't know anything about the issues surrounding this hiatus BUT I thought that this year for TAXONOMY DAY, it would be a GOOD time to refresh the public as to what services natural history collections perform for both the scientific and "greater good" of society...
As I described in one of my last posts, the Natural History Museum is essentially THE HABITAT for the taxonomist (as well as many other scientists!)
1. Specimen libraries that help us ID and understand biodiversity
Most people don't realize that behind the exhibit floors of dinosaurs, shells, minerals and other awesome displays there are actually large collections of natural history artifacts- shells, plants, insects, skeletons, and many more specimens of different organisms and mineral specimens from all over the world. Some local, some from very far away.
Just to be clear, these aren't just "stored" to get them out of the way, these specimens are ACTIVELY STUDIED and researched by scientists all around the world. I would say that this is the primary function of natural history museums. They house and care for biological (and in some cases geological and cultural) specimens that serve the scientific community.
Collections like this one are RESEARCH centers for these kinds of natural artifacts. In the context of biology, if you want to know what some Antarctic fanged rotifer looks like? Find the museum with all the Antarctic rotifer specimens and compare yours with professionally identified one in the collection!
If you think you have some kind of fossil that you'd like to check as being from specific stratum of rock? Compare it against the one in the natural history collection!
At one of the museums' I've worked at, they actually have a representative of EVERY phylum of animal! So yeah, you wanna know what a loriciferan is? And finding one isn't convenient? You can go look it up and find it!
What makes Natural history collections so critical to taxonomy? This is frequently where the vouchers or TYPE COLLECTIONS are deposited.
As I've described earlier, these are sort of the "first issue" of a new species. Essentially the voucher showing the original "intent" or concept of a species by its original author
These type specimens are kept for collections of all sorts of plants, animals and fossils in natural history museums all around the world. They allow scientists and other researchers sometimes HUNDREDS of YEARS down the road to confirm what a particular species looked like based on a particular author's description..
Sometimes, this preserved material also retains useful DNA for subsequent extraction and study to understand ancient relationships or other study areas.
2. New Species are Described from Natural History Collections
So, if you remember from the recent Okeanos Explorer dives to the Hawaiian Islands, we saw on several occasions, THIS starfish species. A goniasterid, called Circeaster arandae, was a species I described in 2006!
On multiple occasions I've described how I've descried new species from different parts of the world. I've got the new species I've described listed here and I'm up to around 31 of them by now.
Natural history museum collections are a natural place to describe new species because in many instances, you ALREADY have the other species present as a reference species for comparison as well as much of the literature.
Once a new species is described. It remains with the museum until one of three things happens: the specimen fades away OR the museum collection fades away OR human society ends.
Either way.. vouchers for species are supposed to be kept "in perpetuity" and that's a LONG time...
I have literally met the 4th generation of descendants of scientists visiting the museum who had specimens deposited in the museum based on work finished in 1846!!!
3. Museum Collections: Where Scientists Gather
During one of my last visits to Paris, a convergence of about half a dozen scientists from 4 countries led to a workshop on New Caledonian marine biodiversity!
These efforts benefit everyone as folks get their "heads together" to pool data and resources in order to solve bigger problems and to examine big issues in conservation, biology and other related fields.
4. Museums & their Collections are Research/Conservation Hubs
As part of this whole dynamic, many, MANY government and non-profit organizations hang their hats in and around natural history museums. You've got biodiversity databases and taxonomic information? Then you've got researchers and others who need to research that information and manage it.
Showing people "the real deal" is the often the BEST way to educate. Models and such are nice but when you are able to hold a 450 million year old fossil shell in your hands? A REAL piece of history???
Plus, you often have scientists and educators who know their way around specimens and are more than happy to share the details and explain in the best way possible??
AND, many, many citizen scientist and natural history fans gather at museums. Many, MANY artists often sit and draw/illustrate specimens in the main display halls of many museums. Many citizen organizations meet at natural history museums..essentially inspired by the collections!!
Collections motivate all of the activities above! But remember that they don't necessarily happen on their own! Sometimes you can take one from column A and one from column B!!
How can you beat that??
So.. SUPPORT your natural history museum and their COLLECTIONS. They play an important role in supporting biology and research.
Even WITHOUT money for research activities, there's a lot of costs that go toward supplies.. labels, boxes, and most importantly trained personnel to help maintain the collections.
Happy Taxonomy Day!!
Inner Space 2 by NocturnalSea on DeviantArt
Cabinet of Curiosities: An Anoxic Metazoan by NocturnalSea on DeviantArt
Sirius Passet fauna by NocturnalSea on DeviantArt
Lobopods by NocturnalSea on DeviantArt
Anomalocaris group by NocturnalSea on DeviantArt
False Ammonite by NocturnalSea on DeviantArt
Haeckel Yithian by NocturnalSea on DeviantArt
crinoids hereand a few from the Hawaiian Okeanos expedition.
Here's a hyocrinid "pinwheel" crinoid form the Okeanos dive to Indonesia! (INDEX-SATAL 2010)
For those who might not be familiar with stalked crinoids, they are the ancient ancestors of modern day feather stars (aka comatulid crinoids).
Stalked crinoids are fundamentally composed of three main regions: the calyx (or cup), arms and stalk which is very nicely illustrated by this diagram from the Field Museum in Chicago!
Stalked crinoids feed on food particles in the water column using their arms which they move down to the mouth located at the top of the calyx (or cup). The stalked and unstalked forms have an unusual relationship which you can read about in an earlier post here.
Let's start off with this gorgeous one calledAcanthocrinus rex! from the lower Devonian of Germany. This image was reported by crinoid scientist Hans Hess as "certainly one of the most beautiful crinoids ever found.." Sadly, this specimen was lost in World War II.
|This image from: https://geo-ebooks.tumblr.com/post/127610816184/acanthocrinus-rex-j%C3%A4kel-from-the-lower-devonian|
Here is: Onychocrinus ulrichi a fossil crinoid from the Edwardsville Formation, Lower Mississippian; Crawfordsville area, Montgomery County, Indiana, USA.
Christmas star theme for #FossilFriday ? Acanthocrinus spinosus from the Devonian Windom shale of New York. pic.twitter.com/KejobiKyJR— David Clark (@Clarkeocrinus) December 18, 2015
Still searching for info about my Acanthocrinus spinosus from Dev. Windom shale in NY. #crinoid #fossil pic.twitter.com/CdWOSMWt— David Clark (@Clarkeocrinus) May 2, 2012