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Articles on this Page
- 03/12/14--04:52: _Echinoderm & The In...
- 03/18/14--06:25: _Echinoblog Travelog...
- 03/26/14--22:17: _Echinoblog Travelog...
- 04/01/14--03:49: _EVERYTHING there is...
- 04/08/14--15:30: _What are the DEEPES...
- 04/15/14--19:06: _Watching Brittle St...
- 04/22/14--15:50: _Learning about Luid...
- 04/29/14--21:18: _5 Echinoderm Highli...
- 05/06/14--20:51: _Stalked Crinoid Rou...
- 05/13/14--20:38: _New Paper! New Spec...
- 05/20/14--19:47: _Brittle Stars are E...
- 05/27/14--21:04: _Snails that eat Sta...
- 06/03/14--21:45: _P is for Parasitic ...
- 06/10/14--13:25: _The Hippest Post yo...
- 06/17/14--21:02: _The Cousin Itt of S...
- 06/20/14--15:44: _The Things & Critte...
- 06/24/14--19:21: _5 NEAT things about...
- 07/01/14--05:07: _5 EPIC Deep-Sea Gia...
- 07/09/14--06:58: _The Colorful Challe...
- 07/15/14--21:00: _Sea Cucumber Skin U...
- 03/18/14--06:25: Echinoblog Travelog! Pt. 4 Stories from Tsukuba & Japan!
- 03/26/14--22:17: Echinoblog Travelog: Japan: the things I will miss.... Pt. 5 (final)
- 04/08/14--15:30: What are the DEEPEST known echinoderms??
- the Bathyal at roughly 700 to 1000 m
- the Abyssal at about 2000 to 4000 m
- the HADAL from 6000 to 10000 m
- In the upper two boxes is Perlophiura profundissima, which has been collected between 2265 and 8015 meters.
- Lower, left box is Homalophiura madseni, collected from 6156 to 7,230 meters!
- and finally in the lower right hand box is Bathylepta pacifica which occurs between 5740 and 8006 meters! (thanks to Sabine Stohr for tipping me off to the correct species!)
- 04/22/14--15:50: Learning about Luidia! 5 Things about The OTHER Sand Star!
- 05/06/14--20:51: Stalked Crinoid Round-Up!
- 05/13/14--20:38: New Paper! New Species! How the Blog Informed my Research!
- 05/20/14--19:47: Brittle Stars are EVERYWHERE: 5 EXTREME Ophiuroid Habitats!
- 05/27/14--21:04: Snails that eat Starfish! Predation in the tropical Indo-Pacific!
- 06/03/14--21:45: P is for Parasitic Snail! Enter: The Eulimidae!
- 06/10/14--13:25: The Hippest Post you Know! New Hippasteria species!
- 07/01/14--05:07: 5 EPIC Deep-Sea Giant Isopod (Bathynomus) Observations from JAPAN!
- Stuffed plushie toys (3 sizes There are gold & silver variants
- Tiny candy & bottle top toys
- various "designer vinyl" kaiju toys
- Mobile iphonecase (in silver AND gold!)
- White, translucent white plastic Bathynomus figures/statues
- and of course, the Numazu Aquarium exclusive SOCKS!
- 07/15/14--21:00: Sea Cucumber Skin Up Close! Bizarre & Beautiful!
To me, THAT is a huge message. There's folks in Japan who buy these because they think these creatures are interesting! You can even buy deep-sea biology books at 7-11 in Japan!
Plush toys are gaining momentum, there's even a set of Paleozoic invertebrate plushies!!
The National Museum of Nature and Science of Tokyo had a fun set of Paleozoic invertebrates made into plushies! Here's a carpoid! (Paleozoic echinoderm) But there was a whole Cambrian set which I'm not showing here...
4. But the BIGGEST THING? small toys. Also known as gashapon! As mentioned earlier, tiny little 2-6 cm replicas of the real thing. Part of different sets following various themes for collectors..
For example, highly detailed Paleozoic invertebrates! Eurypterids and trilobites! (carpoids & others are also available).
|This image from the Monterey Bay Aquarium Research Institute!|
Where better to live/feed than on the "top dog" starfish predator like Solaster? (or any starfish for that matter!)
Travelling to foreign lands and new places means trying new foods and dishes that you don't normally get to try when you are at home. Sometimes, these dishes can be quite exotic.
Case in point: after a presentation at the University of Tokyo, I was treated to some hospitality including the opportunity to try hoya aka raw sea squirt or tunicate!
The shower is nozzle connected to the sink faucet. Very efficient. There's a shunt switch that routes water either to the faucet OR to the shower head. The shower head is used in the bathtub, where it can drain. But it is stored on the wall up there over the sink.
Sometimes you forget that the shunt switch is turned to "shower" instead of "sink" AND you have replaced the shower head on the wall.
Looking to brush your teeth and BOOM! That was messy.
|Info for the quake can be found here.|
Hopefully, this trip will only be Part One!
Sweets!but not chocolate or the usual western types...
P.S. These are surprisingly accurate....
(Happy April First! based on an old joke by Alex Kerr!-used with apologies)
and of course 2012 was James Cameron's big dive in the Marianas Trench!
|Image from NPR|
Echinoderms are DEEP. They live in the deepest depths of the ocean..
But how deep are we talking?? Most folks think of "deep" as anything beyond the intertidal.
Many biologists think of "deep-sea" as anything below 200 m, which is where roughly where light stops penetrating. But then you get beyond THAT... then you start entering the REAL deep sea... the ones where biologists start saying stuff like "THAR be where dragons have lease..."
Here is a chart from CNN (from the Cameron dive) which gives you a sense of scale about what these zones mean..
|Image from CNN here|
Sources for this survey include Belyaev's "Hadal Bottom Fauna of the World Ocean", the former Online Echinoderm Newsletter World Records page and the Smithsonian NMNH specimen database!
Pourtalesiidae: The "coke bottle" urchins! I have written about these bizarre deep-sea sea urchins before. YES, these are sea urchins, albeit highly strange ones.
They have EXTREMELY thin and delicate skeletons, which can be almost paper thin. They live by burrowin through and digesting mud on the deep-sea bottoms. Records for the genus Pourtalesia sp. (usually only fragments are recovered) have been collected from 6,850 meters in the Java Trench.
Freyellid brisingidan starfish: Freyastera sp. and Freyella sp. Brisingids are starfish that use their arms to pick food out of the water (more here). All the members of the Freyellidae occur in the VERY deepest depths. Typically below 1000m, but many occur between 4000-6000 m. But the deepest record for a freyellid was Freyella kurilokamchatica from 6860 meters.
"Mud Stars" Family Porcellanasteridae. NOW we're talkin. This entire family lives on muddy bottoms deep on the ocean floor, where they swallow massive amounts of mud for food. Similar to the mud star Ctenodiscus (here). The specimen figured below from the NMNH collections is from 6, 250 METERS below the ocean surface! Deepest record for this species, Eremicaster vicinus is from 7,614 meters! These live in the deepest abyssal-hadal bottoms around 4000 to 8000 meters.
Here's a post about their shallower relatives. And you can always find more on my blog about them. Pic below is from 2000 m.
The deepest record for Hymenaster is for a species from 8,400 meters in the Kurile-Kamchatka trench! So, Hymenaster (species remains undetermined) currently holds the record for deepest starfish. But who knows what new specimens and video remain to be discovered!
The plate below is from this paper by Belyaev, G.M. & N.M. Litvinova, 1972: New genera and species of deep-sea Ophiuroidea. - Byull.mosk.Obshch.1spyt. rir. 77, 3: 5-20. (In Russian)
|From Belyev & Litvinova 1972|
|Bathycrinus carpenteri from the SERPENT website|
There's a LOT of diversity of sea cucumbers at the >5000 meter depth range. All of the swimming sea cucumbers live at these depths (click here)
And of course, our old friends, the SEA PIGS!! (the one shown from 1500 m). Many members of the Elpidiidae, the group to which the sea pigs belong are among the deepest known. Several species occur as deep as 9,500 meters!
But the winning sea cuke? the DEEPEST ones? Members of the Myriotrochidae, including Myriotrochus. Records for these sea cucumbers go down to 10,687 meters!!! The NMNH has records of Myriotrochus bruuni from the Philippine Trench at depths of 10150 to 10190 meters! So yeah, if Cameron didn't see any of these when he was down there? That's HIS problem!
This pic is from a Myriotrochus from the Kara Sea, but you get the idea.
|this image from this Russian page|
So, yeah. Sea Cucumbers. Deep. And don't you forget it!
Today, a cool assortment of unusual videos of brittle stars digging themselves into the sediment!
hmm.. yes, I know that doesn't sound all that special but brittle stars are some of the most abundant animals on the planet. In some settings, such as the deep-sea they are thought to comprise an incredible amount of biomass. As I've written about before, the Amphiuridae, which often make their home in sediment and hiding in mud are among the most diverse groups of brittle stars.
For the topic at hand, some of these videos are pretty amazing. Enjoy!
We start with an Antarctic species, Ophionotus victoriae doing its thing in a special aquarium and its thing is AWESOME.
A gorgeous video of Amphiodia occidentalis from Bodega Head in the North Pacific!
Here is a typical burrowing type of brittle star from the family Amphiuridae, in the genus Amphiura shot here moving through some loose sediment.
If you want an idea of how important the movement of these individual brittle stars is ultimately importatnt, scientists have made videos of their communities in the sediment. They "turn over" and process the sand/mud pretty readily.
Being buried all the time also helps in preservation of brittle stars as fossils...
and we close out with one of the most gorgeous brittle star videos ever shot "Emerging" by Robert Suntay featuring what looks to be Ophiopsila sp. as it emerges from its burrow..
EMERGING from Robert Suntay on Vimeo.
|Luidia clathrata from the Wikipedia page! thank you!|
Some species, such as this Luidia alternata from the Southeast United States were recently mistaken for brittle stars by some, no-doubt, well intentioned but misinformed journalists! (here) Just to clarify: these are NOT brittle stars. Go here to see some characters you can use to tell them apart.
This group of starfish is named for the Welsh naturalist Edward Lhuyd who went by the latin name Luidius!
Luidia was an important animal in the big "Which starfish is primitive" arguments in the early 20th Century, and there was one time when this animal was part of a big argument that raged in the pages of the journal Nature...
Let's learn about Luidia!
1. Where Do They Live?
Sea stars in the genus Luidia typically inhabit shallow-water, tropical to temperate water places among sand or mud. Basically, wherever loose sediment is found. In this respect, they are similar to the better known "sand stars" in the genus Astropecten. (Also a reason why common names don't have much use for scientists).
They use their spines and feet to bury themselves into the sand, or mud or whatever sediment they live in/on....
Here's a big Luidia maculata buried in the sand. Disturbed and then turned over..
I would note that the reason you often see these washed up after storms is because so many of these stars live on sandy bottoms. When you have any kind of turbulence they get "blown" up and washed onshore.
2. What Do They Look Like?
Luidia can be pretty plain looking. But body form in these is pretty distinctive.
Arms are long and straplike (Luidia clathrata from the SE Atlantic shown here).
These vary in size on the center of the disk relative to those on the sides.. Spines are present on the lateral edges of the animal....
Some have elaborate patterns.... (L. maculata from Singapore)
Some with sharp spines!
3. Diversity: How many kinds are there?
As mentioned earlier, there's some 49 species of Luidia known. They occur in the Atlantic, Pacific and Indian Oceans in temperate to tropical waters. A few live in deeper water.
Some, such as this Luidia clathrata from the SE Atlantic coast of North America are 5-rayed and kind of plain looking. Albeit with some coloration..These are pretty medium sized (see pic above) but the disk is maybe about the size of a quarter or a half dollar...
Others, such as this Luidia superba from the Galapagos are HUGE. This species is one of the largest known (see here). This species gets to be easily 2 feet across....
4. What Do They Eat? and How?
Luidia (and the family Luidiidae) are members of the Paxillosida, which is to say the "Mud stars." Almost all of these swallow either prey in sediment or sediment in order to find food.
Luidia is predator and feeds on a variety of prey which live in mud, sand or other sediment. Prey items vary but they include sea urchins, snails, clams, brittle stars, other starfish (see below), sea cucumbers and even tiny crustaceans...
But, as with other members of this group, they lack an eversible stomach (such as what you would see in say, common intertidal starfish). So, they actually just SWALLOW what they eat WHOLE.
You can get an idea of how this works by watching this..
|From the SERC Invertebrate Gallery|
If its one thing I've observed a lot of since starting this blog is how many sea stars are actually HABITATS for other animals. aka 'commensals' wherein the host is unaffected by the presence of the critter taking advantage.
I've written about how closely some polychaete worms have relationships with sea stars before. (here).
A 2002 paper by H. Kohtsuka at Notojima Aquarium and my colleague Toshihiko Fujita at the National Science Museum of Tokyo (Reports of the Noto Marine Center 8: 17-27) shows that several polychate worms live in association with at least two different species of Luidia, including Luidiaquinaria and the large, multi-armed L. maculata in the Sea of Japan.
See below Fig. 1 from their paper showing worms in various living positions...
And from awhile back, was this fascinating video by Blennywatcher of this crab running along in association with this L. maculata. Undoubtedly there are more associations but these two are good examples....
Other BONUS FACTS about Luidia??
A big multi-armed Luidia on its tippy toes? is REALLY WEIRD... For more info on this GO HERE.
As a big marine/deep-sea biology nerd, I've been following the recent NOAA Gulf of Mexico Expedition undertaken by the Okeanos Explorer via the live stream on their website. For those who may not be familiar, the Research Vessel (R/V) Okeanos Explorer deploys an ROV (Remotely Operated Vehicle) aka a robot submarine which can deploy to 6000 meters.
The ROV has cameras that basically broadcast a High definition signal back to the ship, which then provides the stream to everyone via the Internet. You can see this here. The feed is usually narrated by two scientists who provide running commentary on the many biological and geological points of interest which they observe.
BUT they have a direct line to scientists on shore, who can instantaneously provide their expertise and/or knowledge without having to actually be on the ship. I am one of these experts and I've called in every so often to observe or point out some interesting and/or useful point.
Last year I was able to help provide some identifications and/or commentary for the 2013 Northeast Atlantic Canyons Expedition undertaken by the Okeanos Explorer. Go here to see a roundup
The current expedition was from April 10 to May 1st and its last cruise will be this week.
I've been watching their live feed as best as I can between various projects and day-to-day work. Many screengrabs and so forth have been made by several folks on Twitter, including myself (@echinoblog), Dr. Chris Kellogg(@DrChrisKellogg), the Voss Laboratory (@VossLaboratory), Steve Auscavitch (@steveauscavitch), NOAA Ocean Explorer (@oceanexplorer) and of course, the Okeanos Explorer itself (@okeanosexplorer)...
BUT, the video feed can be long and filled with mostly uneventful transit and/or deep-sea bottoms until something interesting pops up! And even under the best of circumstances, important observations are missed and/or the ROV has to move on.....
So today, I've taken the liberty of rounding up 5 echinoderm-related observations condensed from the last 2 weeks of expedition video stream which I thougtht were interesting!! (sorry if you were more drawn to fishes, sedimentary structures or coral....)
These are presented here with my own personal comments on each! Enjoy!
5. Swimming Sea Cucumber Pooping!
Swimming Sea Cucumbers! MANY were seen in the first couple of weeks of the expedition on the abyssal bottoms! (>2000 m depths). They in fact, saw many different species. I've written about swimming sea cucumbers here...
But perhaps one of the most photogenic and frequently seen is Enypniastes. These live a combined bottom and swimming life. They live primarily on the bottoms, extending their mouth tentacles to the bottoms looking for fresh, organic (but nutritious!) goo which has fallen to the sea bottom...
But what made this Okeanos observation so memorable?? Enypniastes was shot not only eating.. but DEFECATING!!!
You can see its intestine RIGHT THROUGH the transparent body! And that's the "cleaned" sediment pooping out of the end!
Its likely that the processing of organics through these sea cucumbers is important for organic and carbon cycling on the deep-sea floor...but here are FIVE good reasons why sea cucumber poop is so important! (not all reasons may apply to deep-sea species but these give you a good idea why seeing this happening is important).
4. Goniasterid starfish (Peltaster?) feeding on glass sponges
All throughout my PhD, I worked on goniasterid starfish. This is a family of sea stars with over 256 species! One of the most diverse among the Asteroidea. But there was maybe less than a dozen species that we knew anything about their biology or had even EVER seen alive.
What do they eat? What color are they alive? Most goniasterids live in deep-sea habitats and so, very few of them had ever been observed doing well... anything, really.
So, every new observation, even anecdotally is potentially important and definitely interesting!
So, here we have a "cookie" shaped goniasterid, possibly Peltaster or something related (positive ID unclear from the pics)... but hunched over some glass sponges upon which it is most likely feeding.
A closer look.... I can only wonder what it gets out eating a glass sponge which really doesn't have much in the way of tissue to digest...
When we talk about deep-sea starfishes, ESPECIALLY the ones that live below 2000 meters, we really don't know a lot about their biology. At one time, seeing ANY deep-sea starfish alive was biased by having to keep it in a cold-water aquarium AND by having to bring it up to the surface. RARELY have these species been seen alive, much less in situ (i.e. in their natural setting)
But even basic questions were often unknown. What was its natural posture? What color was it when alive? What was it eating? What was it doing? How was it moving?
This species, Dytaster insignis has been known primarily from dead specimens, usually with a gut, gouged full of mud similar to this porcellanasterid...
Another great starfish we got to see alive and in situ (i.e. in its natural setting) is a goniasterid starfish species called Nymphaster arenatus.
2. Mysterious 6-rayed starfish. Ampheraster alaminos or ???
Perhaps the BEST of the various stories that come out of watching these videos is wondering which ones are possibly NEW species.
So, take this for example. Seen on this expedition in the Gulf of Mexico but ALSO on the North Atlantic cruise last year.
1. What are Sea Urchins doing on Seep Mounds?
Perhaps one of the most intriguing series of observations on this expedition came from a group that I don't personally work on: the sea urchins aka the echinoids.
So, early on in the dives the ROV spied these huge chemosynthetic communities, including MANY mussels as well as bacterial mats and other associated faunas...including these sea urchins (genus Echinus perhaps? )
What's weird about this? Well, most echinoderms are pretty dang sensitive to water quality, especially when the water's filled with hydrocarbons or other unpleasant materials in it. So that's one thing. But okay... let's say they are tolerant, what's ANOTHER weird thing?....
When you take your basic Invertebrate Zoology course, you get told that "regular" urchins (i.e., those which are ball shaped like this one vs. sand dollars, and etc.) mainly eat plant matter, kelp, etc. Now, I've discussed in past posts how diverse the feeding modes of sea urchins can be...ranging from herbivores to filter feeders or even carnivores!
But we don't see any of the usual food. So WHAT are they there for? Bacterial food? Perhaps something growing on the chemosynthetic mussels??
1a. BONUS Sea Urchins Feeding on Corals!
First.. a big THANK YOU to Steve Auscavitch and the Voss Laboratory for capturing this image while I was off doing other things...
But yes. Sea urchins feeding on corals. We saw lots of this in the North Atlantic Okeanos expedition last year. It was new then and remains new here....
Extra Non-Echinoderm Observation: PALEODICTYON!
These were traces observed on the deep-sea bottom. Its unclear exactly which organism creates them but similar traces have been see since the Paleozoic.
One famous oceanographer, Dr. Peter Rhona made it a life obsession to find out what they were... (see this piece in the NYT).
and another account of these as "crop circles in the deep sea" at Hindered Settling. According to various sources on Twitter, Paleodictyon was also a favorite topic of the famous paleontologist Adolf Seilacher, who passed away recently..
Most modern crinoids go by the name "feather stars" (for example here) because their adult forms no longer retain the long stalk present in these older forms. This heritage, however, IS retained in feather stars, which have a stalk when they are juveniles (see this post).
Crinoid feeding biology is fundamentally a simple matter. Arms are outstretched into the water current and food is caught by the branching on the arms and moved to the mouth present in the cup (also called the calyx which is a damn good Scrabble word).
Of the approximately 600 species of crinoids alive today, about 95 of them are stalked but belong to a diversity of different genera, family and species. Nearly all of these live in the deep-sea where they occur at great depth, ranging down to the deepest known depths (9000 meters!)
NEW species of stalked crinoids continue to be discovered!! Such as this Antarctic species described by my French colleagues at the Museum national d'Histoire naturelle in Paris.
One of the primary differences in overall morphology is how and whether they are attached.. As you can see, the yellow Hyocrinus (family Hyocrinidae) on the left side is permanently anchored to the rock, whereas the Endoxocrinus (Isocrinidae) on the right side has a stalk that ends as kind of a tail, which allows it to crawl around and move. (presumably to escape predators as outlined here).
Feather Stars (i.e., unstalked crinoids) occur mostly in shallow water and can actually swim if threatened.. (see here).
Today, I just thought it would be cool to share the diversity of stalked crinoids that are around TODAY. Life modes of fossil species can be pretty amazing as outlined here.
We start with an unusual stalked crinoid.. Neogymnocrinus richeri in the Sclerocrinidae...
These have a short stalk with these thick, unusual arms and a palm-like cup. Its possible these feed a little more aggressively than their other filter-feeding cousins...
Endoxocrinus? (I think) from the tropical Atlantic
An interesting stalked crinoid I don't recognize with distinct segments on the stalk.. from Indonesia)
Another interesting one (unidentified) with only 5 arms..(from Vailu'lu Seamount in the central tropical Pacific)
The distinct yellow stalked crinoid Hyocrinus from the North Pacific
A red stalked crinoid species from Indonesia
Another interesting red stalked crinoid from Indonesia. Note the weird fuzz on the stalk? Possibly hydroids or some other kind of animal....
Some of you may remember that we saw a stalked crinoid in the North Atlantic via the Okeanos dive last year which ALSO had these interesting growths on the stalk...
Here's one of the deepest occurring kinds of stalked crinoids, a bathycrinid which seems to be anchored in sediment..
|image from SERPENT archive|
|photo by Dan Blake, via the ATOL website.|
Chondraster grandis? from the North Atlantic. We know almost nothing about this species..
|From this EOL page via SERPENT|
And this line of thinking from the blog eventually made its way into a nice part of the paper discussion! which for me, leads to a nice paradigm shift about this poorly known group of animals!
The internet observations had colored and further fleshed out my published work! Who knows how it will be corrupted by blogging next? Woo!
Brittle stars are EVERYWHERE. They are not only the most diverse (over 2000 species), but also the most ABUNDANT of echinoderms (go here for the full thing)
The truth is that they live frakkin' EVERYWHERE. The diversification of brittle stars is thought to have been successful mainly because they've found a niche just about anywhere and everywhere they can! They live in all the nooks and crannies on the marine bottoms: buried in sediment, rocks, sponges, corals so on and so forth..
Some Brittle stars live in some of the deepest places on earth down to >8,000 meter depths! (here)
But brittle stars also manage to find some pretty crazy, unusual and just downright SURPRISING places to live. Are there ANY habitats which which they cannot exploit???
Here's a few of them....
Ophiuroids GO where other Echinoderms fear to tread!
1. Floating Plastic Garbage.
Although garbage/debris is created by humans, it may functionally serve as just another venue for brittle stars to practice rafting, which is one means for animals that don't swim as adults, to be dispersed widely via ocean currents.
I've also written about the tiny, 6-rayed brittle star, Ophiactis which has likely been transported all around the world via human activity, probably like this and several other ways.....
Speaking of one of those other ways??I wrote about brittle stars "rafting via jellyfish" in one of my posts from 2009! (here) But the short version is that some species are regularly found inside jellyfish for uh..... various possible reasons (go see the post to see the discussion why..)
another great pic of this can be found over here!
|via Thomas Peschak Photography|
Here is ANOTHER place you generally don't expect to find echinoderms. Why? Because most of the environment around hydrothermal vents is not just, very, VERY hot but also filled with toxic chemicals, such as hydrogen sulfide.
|East Pacific Vent from this R. Blake's page|
Observe Ophiolamina eprae from the East Pacific Rise. And there are actually about three others that live in and around vent settings...
This species actually looks like it lives directly in the path of some of the hot water and toxic materials...
|Image via Florida shellfish ID guide|
Salinity in ocean water ranges about 30-50 ‰ (ppt) and freshwater is generally less than 0.5 ‰ (ppt). A lot of sea stars, for example start to get unhappy when you drop below 30ish ‰ (ppt).
Another species in the Amphiuridae, Amphipholis squamata has been recorded as withstanding salinity as low as 5 ‰ !!
Here's one species, Ophiomaza chaotica a strikingly black and white species which famously lives on feather stars! A short write up on it at Wild Singapore here.
and I found this pic of a tiny striped brittle star living on Ophiomastix annulosa Another example of commensalism?? Maybe one just incidentally crawling on the other? It wasn't actually clear and unfortunatley I couldn't actually find a record Ophiomastix-on-Ophiomastix action..so for now a mystery...
There ARE some accounts of brittle stars living symbiotically on other brittle stars but for various reasons, those are the subject of a future post!
UPDATE: Should also have mentioned that brittle stars live on that other extreme deep-sea habitat-WOOD. But that's a story for another day...
|Borrowed from my friends at Deep-sea News|
In cold and temperate water habitats, starfish, especially asteriid starfish are often predatory. ESPECIALLY on mollusks! Famously on bivalves and clams but also quite a few gastropods aka snails.
The Triton Vs. Crown of Thorns (Acanthaster planci)
Just walked out of Godzilla and want to see two big monsters fight it out?? You've come to the right place!
The "Triton's Trumpet" is a large snail with a shell that is often up to two feet long. Because it is large and showy, it is often sought after as a souvenir. Here we have not one but TWO videos of these giant snails attacking the very spiny Crown of Thorns starfish, a voraceous predator of corals
When the snails get to work, they often appear to be successful. But even if not, with the crown-of-thorns starfish there's *literally* many more fish (or starfish) in the sea!
this did not end well for the starfish.
The Triton vs. the "Blue Linckia" aka Linckia laevigata
Here..what you are seeing is NOT a hermit crab, but one of these giant triton snails finishing off its dinner, a blue Linckia laevigata, eating it disk first with the legs sticking out of the shell's opening..
Here's what this looks like with a bit more perspective...
The Triton vs. the Cushion Star (Culcita novaeguineae)
Another target species? The big, round, almost pillow shaped starfish Culcita novaeguineae!
A pic to give you some perspective...
Other Indo-Pacific species include Choriaster granulatus
Nardoa novaecaledoniae (Ophidiasteridae)
And in the Atlantic Caribbean (Cozumel), this "triton" snail attacking the tropical Oreaster reticulatus. Honestly, I'm not sure if I've ever heard of this.. maybe something new? Will have to check...
Attacking a small specimen of Oreaster.. maybe O. clavatus?
|via Wikipedia from NOAA photo library|
And of course, its not always, the BIG snails.. the tiny ones can be predatory as well.. Here are individuals of Phos nodicostatum (Buccinidae) feeding on the arm of a crown of thorns..
At some point.. I will add Pt. 2 to this.. PARASITES!! WOOO!!
|From the Eulimidae EOL image gallery-Moorea Biocode|
Behold the Eulimidae! A family of snails, whose primary means of nutrition is feeding on echinoderms...specifically as PARASITES! They pretty much attach themselves to every class within the living Echinodermata: urchins, crinoids, brittle stars, sea cucumbers (remember the sea pigs?) and today's subject... starfish!!
Eulimids are insanely diverse. There's over 85 genera and easily hundreds of species. With likely more being discovered as they are found on their hosts..
If you guys ever need a one-stop shop paper on the Eulimidae, you are in luck! This paper (behind a paywall) includes a summary of biology as well as an overview to all the genera. The acknowledged world expert on these is Anders Waren, a scientist at the Swedish Natural History Museum
Basically, eulimid snails feed by sticking their proboscis into their host and sucking the tasty, delicious juices out of them. This in itself is kind of interesting because most echinoderms use a kind of specially treated seawater (filled with body cells called coelomocytes) as a bodily fluid.
Apparently, its these cells-the coelomocytes upon which the snails feed... Note below, the extended probsocis...
This snail was described as Melanella with what appears to be its proboscis extended and gives you a general idea of how these snails operate...
|Image from EOL's Eulimidae image gallery|
|From the Eulimidae EOL image gallery-Moorea Biocode|
2. Endoparasites! On the OTHER hand..some eulimid snails, get pretty "dug in" and have literally buried themselves in their work!
They basically embed themselves in the host, attach their proboscis directly to the internal arm canals and just suck on em' all day.... This one, Parvioris fulvescens looks like its embedded itself in what looks like Ophidiaster (?)
|From Femoreale Shells via EOL|
3. Parasites of the Deep!
and lest, you think that eulimids only parasitize shallow water reef species, let it be known that many deep-sea starfish are also parasitized by snails! Here is Asterophila japonicus as reported by Sasaki et al. in: Sasaki, T., Muro, K. & Komatsu, M. 2007. Anatomy and ecology of the shell-less endoparasitic gastropod, Asterophila japonica Randall and Heath, 1912 (Mollusca: Eulimidae).Zoological Science 24(7): 700-713.
This species seems to be a host in the astropectinid sea star Leptychaster,where it has burrowed UNDER the disk and lives right above the stomach!
One deep-sea snail parasite, Asterophila rathbunasteri described only in 1994! lives as a gall in the arms of the deep-sea, multi-armed asteroid which lives off the west coast of North America...
This new species was a little tiny thing collected by the Monterey Bay Aquarium Research Institute from Pioneer Seamount in the North Pacific (southwest of San Francisco) in 2005
The third new species we described was found among specimens sent to us from the New Zealand Institute of Water and Atmospheric Research. It resembles the North Pacific Hippasteria heathi but the genetic and morphological data support it as being distinct..
|Image by Dr. Steve Lonhart Via SIMON|
|Image by Neil McDaniel (check out his website here)|
OTHER Related Posts:
New genera and species of Hippasteria related starfish species!
Deep-sea Corallivore Video from MBARI!
So, I thought I would compare with some specimens without the spines.... The genus name Echinocardium means "Spiny heart" and cordatum which also means "heart shaped", so the whole "heart shaped" thing seems to be a theme...
Here's the skeleton (called the test) of one without the spines. (individual alive with spines is the white one shown above) so, yeah, they have a heart shaped skeleton. This is the top surface..
One more cool thing? Echinocardium has a decent fossil record! AND one of the neat things that have been found are the filled in casts of the BURROWS of Echinocardium (or something related) that these animals lived in.. (this one from the Pliocene near Tuscany, Italy)
11. Sunflower Stars! (Pycnopodia helianthoides)
|Image from STRI's O. reticulatus page|
The species name "reticulatus" refers to the net-like pattern on the body surface whereas "Oreas- refers to "mountain"... So breaking it down, the latin name means "Reticulated Mountain Star."
O. reticulatus is a pretty iconic animal for this region. It is so, distinguished that it even occurs on the 1 cent coin on the Common Wealth of the Bahamas!!
These have been made into CUFFLINKS!
and postage stamps!
The genus Oreaster only in the tropical Atlantic, on both the east and west side and is known only to occur in shallow water. Oreaster reticulatus tends to be thought of as being primarily a west Atlantic species.
The east Atlantic/African species of Oreaster is called Oreaster clavatus and varies in color and spination...
|Image borrowed from this excellent French site for identifying marine fauna "Sous les Mers"|
Moving on! Adults do vary somewhat in color (note also juveniles below)... Some lighter
Most times, these are 5 rayed, but occasionally you get the odd one with 4 or 6..
But enough with the intro!! Here we go!
5. Oreaster reticulatus are omnivorous feeders but eat a lot of algae and encrusting food. Often, they feed in feeding "fronts"
So, one of the seemingly constant assumptions (I would say misconceptions) that are often made of sea stars is that they ALL adhere to the feeding modes of shallow-water asteriids, such as Asterias.. i.e., the old trope of "all starfish feed on mussels or clams"I have written at length about the diversity of feeding modes in sea stars. You can see more of that here. and here..
O. reticulatus feeds primarily on microalgae and/or on other kinds of encrusting food. Work by Scheibling (1980 in Marine Ecology Progress Series 2: 321-327) shows them feeding on a seagrass bed where they obtain nutrients from a likely combination of organisms on the seagrass, the seagrass, and organic materials in the sediment, etc. but what's interesting? is HOW they do this...
When Oreaster reticulatus feed, they do so in a FEEDING FRONT!! Kind of like an army across the sand bed...
The pic below hails from the paper cited. The authors describe this feeding front:
A feeding front of the sea star Oreaster reticulatus off St. Croix, U.S. Virgin Islands. The front is moving from left to right. Feeding mounds (fm) of darker sediment surrounded by lighter halos can be seen behind the front on the highly turbated sand bottom. In advance of the front, the sediment appears darker because of a microalgal film which has developed in the absence of sea star grazing in the previous weeks. Average sea star diameter is 0.26 m
|This from Jean-Sébastien Lauzon-Guay, Robert E. Scheibling, and Myriam A. Barbeau. 2008. Formation and propagation of feeding fronts in benthic marine invertebrates: a modeling approach. Ecology 89:3150–3162.|
Also worth noting? Food varies with location. Some feed on algae, but others feed on sponges. In some places, up to 61% of the species were feeding on MANY different sponge species (see Wulff 1995 in Marine Biology 123: 313-325)
Even MORE interesting? Feeding by O. reticulatus is so specific that they can actually tell apart different species of sponges that humans cannot recognize! (see Wulff 2006 in Biol. Bulletin 211: 83-94)
3. Juveniles are a different color/appearance than the adults.
Oreaster reticulatus are members of the family Oreasteridae. As adults, these are big, massive very heavily armored individuals. But when smaller, most have a VERY different looking juvenile form.
This, for example, is a photo of the many growth forms that the Indo-Pacific Cushion star, Culctia novaeguineae undergoes as it gets bigger.
This one is more brown...
3. O. reticulatus "home in" on large aggregations of other O. reticulatus
|Image from Echino LifeDesks. Photo by Simon Coppard|
They performed an experiment, where a big bunch of individuals present on a large sand patch were moved off the patch to about 20 m (about 66 feet) into the surrounding seagrass bed.
As the internet is fond of saying "What happened next, WILL AMAZE YOU!" (or at least, I thought it was interesting...) the starfish then, re-oriented and then moved BACK to the patch, re-grouped with the others within 24 hours! That is, they HOMED in on the OTHER starfish and MOVED there.
How? Probably through some kind of chemosensory cue in the water. i.e., something that those starfish leave behind that informs the others how to find them. So, yes, they can tell where they are and determine where others are as well.
2. O. reticulatus is closely related to another species in the East Pacific!
One of the cool things about many of the animals which are found in the tropical Atlantic and Gulf of Mexico, is that you can often look toward the East Pacific (i.e. the other side of the Panamanian isthmus) and find ANOTHER species which often bears a close resemblance!
I wrote a story awhile back about a starfish species, Heliaster kubiniji, found as a living from in the East Pacific, but ALSO as an extinct, fossil form from Florida.
Long story short? About 10 million years ago the isthmus of Panama was not yet closed. And it was an open waterway between the "Gulf of Mexico" and the eastern Pacific (south of Baja California).
There were MANY species in this area were once connected. Some were one continuous species while others just kind of showed a close genetic connection. Then the isthmus formed about 3-5 million years ago and formed a barrier, separating these two populations.
Before we had better genetics and fossils to tell us about the precise timing, these were often assumed to be "sister" species. In other words, two sides of the same coin.. closely related by only a few million years of separation. But it is now clear to us that several of these diverged from one another much earlier than that. And are thus much more distantly related than was previously thought...
1. O. reticulatus faces "predation pressure" from tourists and studies on populations and reproductive biology do not suggest it will do well if overfished.
Yeah, sorry, this one is not quite as fun or neat as the others, but its important. I've written about the pending threat of "overfishing" starfish species in the Indo-Pacific. This includes the widely occurring Protoreaster nodosus as well as several other fished species (Archaster, etc.)..
In the tropical Atlantic, O. reticulatus is regularly taken as fodder for tourist shops and so forth. The pressure on this industry has become significant and in many places the populations of this species have become locally extinct.
Based on work by Scheibling & Metaxas (see this and MANY other refs) the population of this species are relatively low, ranging from 1 to 5 individuals per 100 sq. meter and don't turn over very quickly. It is unclear how much growth goes into a large sized, adult individual, but it doesn't seem that these are very fast growers.
The species is dependent on the algae and other food found on seagrass beds, which suggests that between collection of the adults and habtiat destruction or disruption, this does not bode well for the big familiar "cushion stars" of the tropical Atlantic..
So, here is a species that seemingly everyone takes for granted but if it has an ecologically important role, maybe one we haven't fully understood? and we're taking it for tourist baubles and souvenirs??
Something to think about...
....and one extra! .. I'll be honest and say I'm not sure if this is pooping...or spawning..
|From the Toba Aquarium's Twipple Account|
In the big world of the Internet, its easy to start dropping names. Not many taxonomists, and too little information. So, let me take a moment to talk about diversity in "giant isopods" aka Bathynomus.
Bathynomus is a genus of deep-sea isopod which occurs throughout the Atlantic, Indian and Pacific oceans, roughly between 200 to 2140 meter depths. Isopods are of course, crustaceans. You may be more familiar with their terrestrial counterparts which go by many common names: "potato bugs", "rollie pollies" or "wood louse". But they're all members of the same group of crustaceans, the Isopoda.
Its easy to get caught up with the excitement associated with the most famous of all the Bathynomus species, Bathynomus giganteus. It is among one of the largest of marine animals and has an easy name to remember. Its species name literally means "Gigantic"Bathynomus.
by Lowry & Dempsey in 2006, Deep Sea Benthos (here) they divide he various species into "Giants" which only reach 150 mm (about 6 inches) and "Supergiants" which reach up to 500 mm (almost 2 feet long!).
Yes. They can get to be bigger than a CAT.
B. giganteus, which occurs only in the western Atlantic is a "Supergiant". About half of the known species are "supergiants". A great summary to B. giganteus was written by the famous (now retired) Kevin Zelnio here, from many years ago..
The Japanese species, Bathynomus doderleini gets to be a decent size. About the length of a hand or foot. But it is apparently collected with some abundance in Japan and as such, has been put on display in several aquaria, permitting many interesting things to be learned about its biology.
There was one account earlier this year of an individual (apparently B. giganteus brought from the Gulf of Mexico) at Toba Aquarium which famously refused food for FOUR YEARS before it finally died in 2013.
|From the Toba Aquarium Twipple|
The Japanese have a surprisingly consistent naming system used in labelling animals. As far as I can tell, this system is used in addition to the standard Latin names used for various significant species around the world. I've discussed some of these for starfish here.
The popular term for Giant Isopod in Japanese is the word for the armor worn by shogun! Gusoku! You can sort of see the resemblance: the overlapping plates and the helmet, etc..
"oo" basically means "big", "guosku" refers to the armor of the samurai. and "mushi" refers to "many legged insect", "bug", or "critter"
|From the Numazu Twitter pics|
What's that? You want MORE??? here's a bunch of amazing observations, spied via social media and etc. about everyone's favorite deep-sea isopod! Some biological. Some cultural...
5. Bathynomus feeding.
Here is a tank in Japan filled with what is presumably Bathynomus doderleini, Watch the fish put in at 0:15-0:20 then, followed by FEEDING FRENZY and subsequent flesh-free fish skeleton!! Forget piranha.. throw James Bond into a pool full of these sometime!
4. There is a surprising abundance of Japanese Bathynomus products
I gotta say. They KNOW a good thing when they got it!! I'm an echinoderm fan, but I respect a culture that loves deep-sea crustaceans!
3. People EAT Bathynomus??
Yes. The full story is over here at Rocket News 24. From what I've seen, this tends to be only B. doederleini, and not the Atlantic B. giganteus.
I only add that Bathynomus is probably NOT a good animal to depend on as a sustainable food source. But according to my colleagues, yes they are edible and not surprisingly, they taste like crab. and are pretty crunchy. Mostly they seem to be deep-fried. But I've heard they also eat them as sushi.
Video report in Japanese is here. But you'll get the idea.
2. Bathynomus Molting
Its not a secret that crustaceans molt. Crabs, lobsters, shrimps. All of them shed their exoskeleton as the body grows. And yes.. isopods also molt. Its been observed in more conventional species.. But has it ever been observed in Bathynomus?? (I couldn't locate an account but maybe it is out there?)
But here is something from the Toba Aquarium's Twipple Account (Twipple is a photohost service). An AWESOME sequence of a deep-sea Giant Isopod undergoing a MOLT!
How many times do you get to see THAT??
First photo was recorded at 9:21 AM (Japan Standard Time),
|From Toba Aquarium Twipple|
|From Toba Aquarium Twipple|
|From Toba Aquarium Twipple|
The Atlantic species. B. giganteus broods eggs, and some terrestrial isopods brood, so brooding juveniles in this species is not a big surprise. Its not clear to me if the Atlantic "gigantic" species does this.
But, clearly, this Japanese species does this. Priceless and awesome.
|From the Numazu Aquarium's Twitter Account|
|From the Numazu Twitter pics|
The other day, I was helping some folks out with an identification of a starfish they had photographed diving, but I stopped short of giving them the full species. "Why?" they asked. "Isn't this just the the XXX?" (they quoted the most common and easily identified species).
"Well. Its complicated."
Hard to explain these things in a a few lines on Facebook or on Twitter so I thought I would take an example of how complicated the whole taxonomy and identification process is, using a widely photographed example, a starfish called Fromia monilis.
F. monilis occurs widely throughout the Indo-Pacific. It goes by many common names, Necklace star, Tiled star, Candycane star, Peppermint star, etc. Scientists don't use those names because they're so inconsistently used and often because its a contrived name in a field guide, created as a convenience for readers.
This species is often seen in the wild and is a common species in the aquarium trade. You can see it in shallow-reefs from Okinawa to New Caledonia, in the Philippines, Indonesia, etc. and over to the edge of the Indian Ocean.
Bottom line: This species is distributed over a VAST area. Because it does, the range of variation (discussed below) is likely to be greater.
F. monilis is a bright red and white species with a distinctive color pattern. The plates on its body surface (i.e., the many circles and shapes you see on the body) are also pretty diagnostic. Most of these starfish are about 2-3 inches (about 5-6 cm) in diameter. So far so good.
Here is what I would say is the most commonly encountered and "typical" form of this species.
|From Wikipedia. Here|
Some of these specimens have been in museums for, literally hundreds of years and remain essential to our understanding of how these species are defined.
Many of these species get distinguished by fine character differences on these specimens. Some might vary by plate pattern arrangements, or by the number of spines present on the underside, or the particular shape of granules present on the surface. Its often difficult to synch up these characteristics (i.e. the species definitions) with qualities of the animal when it was alive.
BUT, because of dry specimens above, we can usually look at a specimen like this crazy thing below and tell that it is STILL Fromia monilis.
Specimens in museums, accumulate over time and can be very abundant, giving us an idea of the natural VARIATION of a species. Size. Body forms. Aberrant shapes. etc.
For a species that we have virtually no understanding of, any character variation (without seeing its presence in the population) might be used to distinguish a separate species. Without an understanding of this kind of variation (or having population genetics data of course), someone who has never seen a human being before could separate me from Morgan Freeman as a different species.
The one above (w/the red disk) is from Borneo.
Is this the same species? But simply with a different color pattern?? Or a different species?? Some species of starfish are thought to vary by color based on their food, does this one as well?? How important is the color as a feature in identification?
Here is another closely related species, Fromia nodosa which occurs primarily in the Indian Ocean. This species is primarily distinguished based on the larger and more prominent round plates running down the radius of each arm. But it looks familiar, doesn't it??
This individual is from the Maldives (tropical Southern Indian Ocean). It shows the same pattern as F.monilis above and the distinguishing characteristic is kind of variable itself. In other words, it doesn't always hold up. Does that mean it should just be consolidated into F. monilis??
This strange thing is from the Philippines. It adheres to the definition of Fromia nodosa (big radial plates, etc.) but its a different color (or at least I assume this is not some photo artefact)!!
And then to make it even MORE confusing.. we have these things from the Red Sea and adjacent areas...
I initially thought this was Fromia monilis but in fact, they might actually be a separate, already established , but this species might actually be a species in a poorly known genus called Paraferdina. Further examination of specimens and research is needed to figure out which one is which... This specimen is from the Red Sea.
This is mainly to demonstrate the limits of how the colors and patterns get complicated quite quickly.
And yes, at some point, someone may work this out.. Lots of diving and subsequent DNA lab time. Plus looking over photos and museum visits! Woo!
But this also explains why scientists, such as myself, are often more reluctant to give you a full species name for a picture when its sent for identification without a specimen. Are these one species? MANY species? Which ones correspond to pre-existing species?
Falling back on the one, most common name can often disguise the truly rich diversity in these wide-ranging, closely related species which are only now, just becoming understood. I argued that this was also the case with the "Bobbit worm" (Eunice aphroditois)
So, yes. Knowing more doesn't necessarily give you all the answers, but it does give you some pretty exciting questions!
|Thelenota ananas Via Wikipedia commons. Photo by Nick Hobgood|
Some of these give you an idea of how colorful and unusual the skin in sea cucumbers can be. This one is called Thelenota rubolineata (the species name literally means "red lines"). This is an example of what the whole animal of one of the pics below looks like...
What do they feel like? Sort of soft and rubbery. Firm. And yes, people eat these species...
Here's a nice roundup of similar closeup photo essays of other echinoderms
Some striking full body pics...