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!
Wednesday (today) was the last day of the Okeanos Explorer's Oceano Profundo expedition, exploring the deep-sea habitats off Puerto Rico in the tropical Atlantic. In the next few months, they will transit through the Panama canal and onto Hawaii!
Among the most commonly encountered of the animals they encountered were swimming sea cucumbers! I've written about swimming sea cucumbers here. Most of the ones we saw were benthopelagic, which is to say that they live on the bottoms but swim when needed/desired. There's really only one that is truly pelagic...
Several different morphotypes (species?) were seen..
1. This transparent one...
Here it was as it was taking off...
Is this the same as this one??
Were those the same as these? An Enypniastes like species (possibly Amperima or Peniagone?)
It left MANY nice traces!
2. This "sea pig" like one.. Elpidiidae?
3. The following ones were all "Benthodytes-like"
This like one had aclear body and with an highly convoluted gut!
This one was a solid purple...
4. and there was this whitish purple beauty!
5. and finally there was this weird pink one we saw yesterday....
This last week had SO MANY exciting observations, so maybe there will be some extra posts soon....
1. FIRST starfish from a Hydrothermal Vent Habitat!!
UPDATE: New Video!
There aren't many echinoderms that live in these types of environments, such as brittle stars, sea cucumbers but this species is the FIRST starfish/sea star to be found in association with a hydrothermal vent habitat!
Why? Hard to say, exactly but it probably has to do with the fact that most echinoderms can't process toxins very well. Their "body fluid" is basically sea water. This is probably why there are no freshwater or land echinoderms.
These starfish aren't "primary" vent fauna, such as big vent worms or clams that can manufacture food out directly of toxic sulfide.. These exist at the edge of the community feeding on the animals that ARE part of the primary vent community. BUT that said, they are pretty important (see below)
Among their food? The weird stalked barnacle, Vulcanolepis The zonation above is probably not that discrete but it does suggest that animals on the "periphery" probably move inside and among all the inner zones, although there are probably several of these that are at the "edge" of their overall zone...
and the very abundant "hoff crab"
There's obviously a LOT we still have to learn about the ecology of this habitat! But as far as understanding a habitat 2000-2500 meters down, in the Antarctic?? Knowing the top predator is a good start!
3. NEW family, new genus and two new species!
So, we have a weird, deep-sea habitat with weird inhabitants. What does the starfish look like??
The skeleton is pretty reduced. A fairly soft and fleshy body wall.
Are both distant relatives of these two weird deep-sea species! What character is shared between them? Features such as these pedicellariae! Tiny wrench shaped claws that cover the body...
5. Named for some deep-sea biologists!
So... WHAT TO NAME THEM?? As a taxonomist, one of my super powers is that I can honor a person, place or thing by converting their name into Latin, thus immortalizing them into the history of science!
As a matter of good practice, its considered more informative to use descriptive terms, but ultimately species names are at the discretion of the author.
This week: Some echinoderm highlights from the 2015 Okeanos Oceano Profundo cruise!
I've made the point in the past about how AWESOME it is to be able to see so many deep-sea animals alive!
As a scientist who works mostly with preserved specimens, our typical perception of these species from dead material is something like this:
The above specimen is a species of Freyastera, a deep-sea brisingid asteroid. Brisingids have special suspension feeding arms with very delicate arms covered by needle-like spines. I've discussed them at length here.
In stark contrast, here is one alive:
Dang. THAT's a world of difference!! And the living observation gives us basic info like color and basic posture. Surprisingly important information when you consider how badly deformed and damaged specimens collected by trawl net can be....
But on the other hand, it is FROM these specimens that we are able to have records of these rare species from past expeditions.
Case in point:
1. Laetmaster spectabilis
We saw this Tuesday. At a depth of 3915 meters from the east wall of Mona Canyon. This is a member of the Solasteridae, which are the "sun stars", which I have written up briefly here.
This is one of the rarest known sea stars, which was known previously from one or two specimens in the late 19th Century on which the descriptions were based. Collected in 1878 by the Blake, a famous oceanographic vessel!
That pretty much means that no one has collected this species for over 130 years! It gave a hard pass to the 20th Century. yow.
2. Plinthaster dentatus feeding!
Another cool thing that we often encounter on these dives is basic aspects of biology which, for deep-sea species, are unknown.