Echinodermata! Starfish! Sea Urchins! Sea Cucumbers! Stone Lillies! Feather Stars! Blastozoans! Sea Daisies!
Marine invertebrates found throughout the world's oceans with a rich and ancient fossil legacy. Their biology and evolution includes a wide range of crazy and wonderful things. Let me share those things with YOU!
As many of you picked up on last week, I've been busy working on starfish at Museum Victoria in Melbourne working with my colleague Dr. Tim O'Hara, one of the world's leading authorities on ophiuroids! aka the brittle stars and basket stars!
While talking to Dr. O'Hara he informed me of of some neat, NEW SPECIES he's described from the deep-sea habitats of the South Pacific New Caledonia in late 2015! These were just too neat to pass up a post on!
1. The Impeller Brittle Star As Dr. O'Hara tells the story, he was once called upon to aid a ship's engineer during his attempted crossing of the Bass Strait on the yacht Irene. A similar looking impeller failed the yacht's engine thus indelibly impressing its shape onto his mind's eye!
Fast forward many years.. and Dr. O'Hara is describing this new amphiurid brittle star from the deeps of New Caledonia.
The large shields on the disk trigger a memory that reminds him of the impeller's shape! and voila! Enter: Ophiodaphne impellera
2. The Game of Thrones Brittle Star: Ophiohamus georgemartini!!
Probably the most STRIKINGLY amazing brittle star Dr. O'Hara described was this one, a new species in the genus Ophiohamus (family Ophiacanthidae), collected from a depth of 275 meters off New Caledonia!
Here's a nice shot of it holding onto this sponge stalk... Note that its most striking feature? Those big crazy spines that are coming off the disk!
If we take a closer look at those big thorny spines coming off the disk...
and compare them with the sharp thorns coming off the crown depicted on the cover art from Game of Thrones: CLASH OF KINGS! This provided the inspiration for the Species name for THIS new species of brittle star!
BOOM! Tim named this one in honor of the AUTHOR of one of his favorite shows: GAME OF THRONES!!
Ophiohamus georgemartini!!
3. Ophionereis sykesi(family Amphiuridae)in honor of his wife who as Tim O' Hara put it "has had to put up with him rummaging around the world's museum collections for years"
An animal with a gorgeous disk plate field which I'm sure is a fitting honor for the Mrs!
4. And finally, Amphipholis linopneusti, described by Dr. Sabine Stohr in 2001.
NOT a new species but an interesting one from the New Caledonia region in that its one of the few echinoderms that I know of which is actually sexually dimorphic! That means there are actually ways of determining males from females using external characters!
The lowermost basal arm spines of males are enlarged, sometimes flattened and hour-glass-shaped, whereas on the females they are cylindrical with a blunt rounded apex. Its a subtle difference to be sure but it exists, which is more you can say for a lot of echinoderms!
If you had asked me 10 years ago if the echinoderm group we would be learning the MOST from would be the OPHIUROIDS I would have been skeptical.
Basket stars? Taxonomy was impenetrably difficult.
non-Basket stars? even worse.
Plus, Brittle stars were tiny, numerous, CRYPTIC animals. Who would study them?
I'm sure we would see "big picture" stuff from sea urchins, sea stars or maybe even crinoids. But brittle stars? It would take a LOT of work to make them an "ideal" animal to work off of....
This week a BIG NEW PAPER in Deep-Sea Brittle Stars dropped in the pages of NATURE!
In other words, Tim identified, requested and/or otherwise retrieved THOUSANDS of records of brittle stars! When you consider how MANY specimens of ophiuroids there are? That is a HUGE effort!!
Based on this analysis of species records correlated with different habitats, especially across different depths, they were able to determine several broad based and IMPORTANT patterns about WHERE brittle stars occur..
Deep-sea species diversity is shaped by energy availability (i.e. thermal energy and nutrients)
Continental shelf to upper-slope species richness consistently peaks in tropical Indo-west Pacific and Caribbean (0–30°) latitudes, and is well explained by variations in water temperature.
In other words, warmer water (heated by the tropics) promotes greater species richness.
Deep-sea species show maximum richness at higher latitudes (30–50°, i.e. polar regions), where they are concentrated in areas with high carbon export flux and regions close to continental margin (richness drops as you get away from the land).
Global brittle star richness, in terms of species, peaks in the tropics at "shallow" continental shelf depths (20-200 m) and upper slope depths (200-1200 m). These peaks drop when you get below 2000 m depths.
The yellow and red in the diagram indicate species richness. These are warmer areas with relatively high nutrients, etc. As the colors fade to purple and blue we see those numbers
decrease on the broad abyss of the ocean floor.
Data are consistent with a hypothesis that deep-sea species richness is maintained by species migration from shallower regions. i.e., "high energy areas feed low energy areas"
Historically we have looked at tropical areas as the focus of conservation efforts, but if we TRULY want to conserve deep-sea habitats we will need to consider the areas which show DEPENDENCE on the shallower regions for diversity.
If this is the case, then our conservation efforts will need to focus on MORE than simple high species diversity. We'd need to further look at places which are DEPENDENT on diversity!
In some ways, brittle stars are one of the most important "model animals' to observe these trends and interactions. Why?
1. Echinoderms, including brittle stars live ONLY in the oceans. No freshwater, or land relatives.
2. Brittle stars are EVERYWHERE. They are one of the most numerically abundant groups of echinoderms known.
This paper is the latest "big thing" to come out of Dr. Tim O'Hara's echinoderm lab at the Museum Victoria!
The Nature paper is sort of the "other shoe" that has dropped with big discoveries. (Remember that
echinoderms have five shoes!) Dr. O'Hara's other BIG news in recent years has been the announcement of this: a comprehensive family tree of the ophiuroids!
The Brittle Star Phylogeny Project
One of the most important and fundamental elements of biology is understanding the evolution and relationships of your study organisms.
How are all the different groups related? (e.g., how are basket stars related to other brittle stars?)
How did they diversify? Where?
What kind of habitat did they diversify into?
Which brittle stars form actual, NATURAL biological groups?
A phylogenetic tree helps to answer all these kinds of questions!
In biology, a well-supported tree with a strong data set supporting it is BIG DEAL. You can literally put ALL the information known about a group, in this case-the brittle stars, into a PROPER evolutionary framework!! Perhaps some lineages share a particular ecological nice mirrored by body form. A tree like this can literally be mined for information for years.
This starts with such immediate things as classification and rearranging all the families to reflect "natural" groupings. In other words whether taxonomic groups such as families or genera-created by scientists based on external characters are "real" or perhaps the result of misleading external appearance. At some point, there's probably a whole POST about that topic!
This kind of data is a POWERFUL statement.
Genetics is powerful stuff. Work on the "Big Tree" of ophiuroids suggests that there are many, MANY more families and SEVERAL orders of magnitude more SPECIES.
Past accounts have estimated about 2000 species? In fact there are likely several TIMES MORE than that. But the exact number remains to be seen..
The work from Tim's lab has nearly DOUBLED the number of recognized FAMILIES of Brittle stars!
He's also turned the classification of these animals on their head! some of the oldest known species turn out to be these interesting deep-sea forms.. Ophiomusium and their relatives! Many surprises!
image from Museum Victoria: http://researchdata.museum.vic.gov.au/brittlestar/www/o_lym.htm
You can sort of see how this ties in with the brittle star distribution paper.. How many of these points on the tree will show relationships between deep-sea and shallow-water species??
These efforts are some of the latest results from Tim O'Hara's "Big Data" ophiuroid work!
This week I do a brief recap of spectacular views from the Okeanos Explorer Expedition to the Marianas Islands which began earlier this week. You can find out all about it on their website here.
Long story short, they are in the tropical North Pacific near Guam with access to some of the deepest trenches and canyons in the world!
This first leg began on April 20th and continues until about May 11th. They have been surveying many very deep canyons and seamounts which are at best, very poorly known and reach 5000 m depths or so!
Many, MANY amazing things have already been seen during the last seven days or so. Here's a recap of the things I thought were most fantastic. But check out their blog here.
1. STUNNING Gorgonocephalid Basket Star Fields So, on May 2nd, the Okeanos Explorer visited Zealandia Bank, in relatively "shallow" depths about 650 to 250 meters. While surveying this area they discovered this AMAZING field of basket stars!! Apparently in the family Gorgonoceaphlidae. You can read one of my earlier accounts on other members of this family live and feed here. But short story: they have elongate arms with hooks that capture prey carried on the water currents.
At this amazing site we had...HUNDREDS of these animals as part of a community of filter-feeding aniamls.
Here's what one looks like closer up.
But again, just spread out EVERYWHERE. At one point Diva Amon, the biology science lead indicated they had travelled about 100 m seeing basket stars to no end!
The animals in this area were all taking advantage of the current flow, including these isocrinid stalked crinoids and those little white corals.
At one point they mentioned that the water current above this field was about 1 knot, which means that the "drag" of this current against the bottom created a good habitat for filter feeding animals.
This area included other species of invertebrates.. starfish and so forth, which could have been feeding on the filter feeders or perhaps indirectly taking advantage of other benefits from the current flow (food, etc.).
Personally, this one was my FAVORITE thing to have seen. Just amazing.
2. Hydrothermal Vent Chimneys
On May 3rd, Okeanos went to a suite of amazing hydrothermal vent chimneys!!! These are places where hot geothermally heated water is vented out through the earth's crust. The dive went down to about 2000 to 4000 m. VERY deep.
This leaches out hot water with toxic minerals into the surrounding water. Surprisingly however, there are a great MANY animals which are able to process these minerals into food!
On this site, it included specialized limpets and other snails, as well as bythograeid crabs, shrimps, polynoid polychaete worms and much more! (as well as bacterial mats growing around the hot water and etc.)
But perhaps MOST impressive was how these vents formed chimneys which took on these very cathedral-like morphologies.
Stunning.
They pretty much spent the whole day going from one chimney to the next..and none were disappointing!
Cladorhizids occur pretty widely as it turns out. Here were two discovered by Okeanos Explorer during the Okeanos leg of this expedition.. Both collected and are probably new species.
Bizarre spines on this one...
This image shows some small amphipods and/or possible food caught on those spines...
This one has a very different body shape with more club-shaped projections....
4. Likely New Stalked Crinoid species!
Stalked crinoids are some of the most... evocative of deep-sea animals, mainly because of their status to some as so-called "living fossils."
I ran these by some of my colleagues (who are stalked crinoid experts).. and this one for example was described as "totally crazy"
This one was apparently seen before from the Philippines/Celebes regionand was identified as a new genus and species! All we have to do now is to collect it!
5. Impressive Acorn Worms (enteropneusts)
Acorn worms are one of those weird groups of worms that have been around for quite awhile and are known to biologists but only recently has there been very good imagery to show off how cool looking they are!
Okeanos saw this one recently, displaying a prolific amount of mucus and a very prominent amount of defecation as it plows through the sediment feeding on the organics!
Here we see mucus with sediment granules as well as poop inching its way long the intestine...
Let's face it, there has been a LOT of amazing stuff on these dives...
Honorable Mentions This fantastic benthic ctenophore! I've discussed these in many posts before (go here) but this is a bottom living species of comb jelly, which are normally observed swimming... They extend their very LOONG tentacles into the water to feed....One individual measured during the hawaiian expeditions went on for nearly a meter!
This was a mystery. A bunch of soft, blobs. Still not sure what it is (foram? sponge? eggs?)..but enigmatic and intriguing.
This sea urchin popped up during the last hours of the hydrothermal vent dive (see aforementioned vent chimneys). A bit of a mystery....
And then yesterday near the mud volcano, we observed not just this large star-shaped trace mark in the sediment but ALSO this little brittle star!
Note how the disk has a kind of raised dark bump?? That's a feature that is pretty unusual for brittle stars. So possibly in the genus Ophiomyces or something else which could be entirely new..
If so, this would be one of the first times its been seen alive!
Predatory Tunicates!
These are actually Chordates like us, but usually tunicates are filter feeders that pick organics out of the water current..
HERE we have TWO genera of tunicates which have adapted to feeding on other ANIMALS!
This one is called Megalodicopia! These have modified their "in" siphon to form a HUGE mouth. Note the little tube on top?? That's the "OUT" siphon. Water goes, with food and flows out through the top (presumably at a higher pressure given how much narrower it is).
Another stalked predatory tunicate is this one: Culeolus. Same basic idea, except that the feeding bits are on a STALK... Water+food goes in one end and out the other!!
and of course, this beast! yeah, yeah, the jellyfish, Crossota sp... always a crowd pleaser!
and compare them with the sharp thorns coming off the crown depicted on the cover art from Game of Thrones: CLASH OF KINGS! This provided the inspiration for the Species name for THIS new species of brittle star! 
