Thursday, April 30, 2015
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??
2. This "sea pig" like one.. Elpidiidae?
This like one had a clear 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....
Wednesday, April 22, 2015
Another new week and another new discovery that I'm overjoyed to share with everyone! A NEW paper I've published in the prestigious Zoological Journal of the Linnean Society! link here This paper was co-authored by colleagues from the British Antarctic Survey (BAS), the National Oceanography Centre at Southmapton, in the UK, the Monterey Bay Aquarium Research Institute (MBARI) and Dave Foltz from Louisiana State University.
This whole paper is basically a monument to scientific collaboration! Basically, I was contacted by the BAS to study sea star specimens they had collected from a new hydrothermal vent system in the Scotia Arc, (Antarctica) which is famously the habitat of the "Hoff Crab" and as it turns out, they encountered MANY different types of animals from this area. Barnacles, "hoff crabs"...and even sea stars (as we can see from this Wired gallery!)
They turned them over to me for study and while analyzing their DNA we found that they were actually closely related to ANOTHER sea star which I had collected during the MBARI 2009 Pacific Northwest Expedition!!
and off we go....
1. FIRST starfish from a Hydrothermal Vent Habitat!!
UPDATE: New Video!
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)
this handy chart from THIS paper by Leigh Marsh et al. in PLOS One! shows this relationship...
2. What do they eat? Barnacles & HOFF crabs!
A study of the food web among the fauna at the Scotia Arc site (in this keen PLOS One paper!) showed that they occupy a fairly important role in this community as one of the top predators.
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!
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.
As I had mentioned earlier, my colleagues and I were ALSO studying this beast... an innocuous looking 6-rayed sea star from the North Pacific!! Collected by myself and MBARI during the 2009 Pacific Northwest Expedition!
Astonishingly, almost EVERYTHING starfish from the area studied during the expedition was new!!
An analysis of the molecules from these two species showed that they were in fact, closely related to one another!!
The truth is that there were not a lot of external characteristics that could have been used to have done the same analysis.
AND molecules also revealed that these two species were part of a lineage or clade SEPARATE from other known species!
HENCE! NEW names were needed! NEW SPECIES! NEW GENERA! and ultimately a NEW FAMILY was needed to properly describe these animals!!
This makes sense. "New" ecosystem and you have new species which compose that ecosystem. Another reason that taxonomy is important!
This makes these species one of the FIRST new families of sea stars to be described since the 70s! (or possibly the 90s, it sort of depends on how you look at it)
4. Unusual and yet related to something familiar...
So, a lot of this might seem kind of alien to everyone, so here's a little something that I think everyone can relate to..
It turns out that these two starfish species are members of the Forcipulatacea, which is the larger group of starfishes to which familiar, intertidal species belong! Read this account of their unusual evolutionary tree!
This familiar Pisaster ochraceus
and Asterias rubens..
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.
The Antarctic species had been discovered by the British Antarctic Survey and these expeditions had heavily involved Dr. Paul Tyler from the Southampton Oceanographic Centre and so it was decided that the Antarctic species would be named Paulasterias tyleri!
Which basically translate's to "Paul Tyler's starfish" (kind of)...
Dr. Tyler is a HUGE name in deep-sea biology, having co-written one of the most important books in deep-sea research in addition to hundreds of articles on deep-sea ecology and invertebrates!
Professor Tyler was recently been made a Member of the Most Excellent Order of the British Empire (MBE)!!(here)
The North Pacific species was discovered under the auspice of my colleague and friend Craig Mcclain over at Deep-Sea News!
And so, I deemed that this second species would be named for him! honoring him was critical!
Otherwise would these species have EVER been discovered if it were not for him???
Craig has written a GREAT post on Paulasterias mcclaini over at Deep-Sea News here.
MORE QUESTIONS!..This discovery is only the START of many MORE questions!
- How does this species tolerate even a little bit of the toxic sulfide in the water?
- Do these have defenses given that they are basically little six to eight-rayed fleshy, water bags?
- How do they capture and eat a hoff crab??
- What is the relevance of this group to the diversification and evolution of forcipulate sea star?
- How do members of this family become so widely distributed??
- How many more of these are out there somewhere??
- IS this 6-rayed Atlantic starfish seen by the Okeanos Explorer the same thing???
My special thanks to Katrin Linse, Jon Copley (@expeditionlog), Leigh Marsh, Dave Foltz, Alex Rodgers, Dave Clague, Craig Mcclain, Lonny Lundsten and Linda Kuhnz!
Wednesday, April 15, 2015
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.
This "cookie star" is in the family Goniasteridae. These get collected quite a bit but we know very little about them. I wrote about some Hawaiian ones here.
Now, we know this one fees on sponges (or hydroids)!
3. Holopus sp. Bizarre stalked crinoid!
This was a great pleasure to see... These are unusual types of stalked crinoids which I have written about before.
This sequence nicely shows the arms extended and withdrawn...
4. Oneirophanta mutabilis! A different kind of "sea pig"!! This one is in the family Deimatidae, so it is different from the classic sea pig Scotoplanes globosa.. So what is a "sea pig" anyway? A discussion for a different day...
with ophiuroid (Asteroporpa annulata? I think?) living on the spines!
But who is it? Not sure..
They could be this species? Asteroporpa annulata?
Other noteworthy observations!!
A Enypniastes like species (possibly Amperima or Peniagone?) with transparent body.... That's the gut you are seeing THROUGH the body wall.
And a Benthodytes also with clear body wall showing the gut!
And a white one.. but again.. transparent body wall...
And finally... one pic full of intrigue! my "phantom" wood starfish?? Did I see it or not? A revisitation to the HD is in the stars....