Okeanos Explorer Communities & Deep-Sea Discoveries!

I'm BACK! After a month at sea with 2.5 weeks worth of dives I've safely returned to "home base" in Washington DC! I was out in the central Pacific with NOAA's R/V Okeanos Explorer on their Laulima O Ka Moana expedition, exploring the deep-sea of the Marine National Monument in the Central Pacific! 

1. Forest of the Weird: Land of the Glass Sponges!
This was probably the most amazing thing I have seen in awhile! (at least since that Basket Star community in the Marianas a few years ago!)

So, the key thing about nearly ALL Of these sponges? Many of them are what's called GLASS SPONGES aka members of the Hexactinellida. That means they have bodies which are made out of silicon oxide!

These often have bizarre and weird shapes. I have done a post about these before here in 2015.

Here's a highlight video of the discovery-basically water currents ran at an ideal rate at the top of this geologic feature making it IDEAL for what seems to be a huge abundance, if moderate diversity of glass sponge species!

Note also how all of them are turned into the current!! We were in this "forest of the weird" for the remainder of the dive (over an hour) so there was quite a lot of it..

Here's few more that show off the crazy architecture.. These varied in height from one to four feet in height..

2. The Carnivorous Sponge Field

This area was kind of the opposite to the one above. Rather than big and obvious, it was quite dense and discontinuous, being present on one big boulder to another...

But what was amazing was that this was composed of a different type of sponge in the family Cladorhizidiae. (possibly in the genus Asbestopluma..) Cladorhizids are not glass sponges and have physical properties more like what's seen in many other sponges. EXCEPT...

...that they are CARNIVOROUS!!!

Wait.. WHAT? Yup. MOST sponges are filter feeders. But in this group, they use glue or spines to capture prey, which are then digested by the animal in question. We've seen different types of these carnivorous sponges before, including some possible new species..  These sponges kind of look like a feather.. a central stalk with fine hairs or spines coming off the sides

Similar to this species in the NOAA benthic inverts guide...

Here..they were present in HUGE densities.. alongside some frond-like bryozoans! and some stoloniferous zoanthids (a sea anemone like cnidarian)  These actually seemed to be pretty thin at first but got bigger, longer and thicker as we encountered them!

Yes.. I suppose I'm overhyping them..but that's basically a "killing field" of carnivorous sponges!  with these projecting into the

Interestingly, this shot above looks like there might be a snail on one of those sponges..so even more going on!

3. This Amazing Farreid Sponge/Acanthogorgia Wall! 
Shallow-water dives can be VERY productive but because of the nature of Okeanos Explorer we tend not to do many of them relative to the really deep dives (>1000 m).

The one we did at Johnston Atoll did NOT disappoint!

This large block and several like it had this AMAZING side flanked on one side by sponges in the Farreidae, but then on another side covered by octocorals in the genus Acanthogorgia!

The coral side (Acanthogorgia) was relatively high current...

versus the "sponge side" which was relatively low current...

and many critters were to be found amongst the corals (such as this... sea slug)

3. Astrophiura! the "sea star ophiuroid" Probably one of the MOST memorable observations for me OUTSIDE of the starfishes was this weird little brittle star!

One of the videographers, Bob, saw it adjacent to the base of one of the sponges. And there it was plain as day!

These animals are TINY. Maybe dime sized. So, the D2 camera's caught a really RARELY ENCOUNTERED and SMALL species.. (about 2000 m depth)

This genus of brittle star was described in the 19th Century by Walter Percy Sladen, the author of the HMS Challenger sea star monograph. He hypothesized that it was some kind of "missing link" between brittle stars and sea stars... (since been disproven)

Here is some imagery of as illustrated by H. Matsumoto.. It has rather famously been shown in echinoderm books as an example of a bizarre form.  Its shape is very similar to those caymanostellids and is thought to be an adaptation to lying flush on the substrate..

Astrophiura kawamnrai n. sp.




4. Pumpkin Sized Echinothuriids Sea urchins! 
This dive started out pretty uneventfully up slope along a cone, resulting in the discovery of a pretty amazing colony of plexaurid corals

As I've mentioned with some of the OTHER high density communities- not only were there corals present but LOTS of other animals living among them.. 

One of the most remarkable? These HUGE echinothuriid urchins!!  For those who might not be familiar.. these are aka "pancake" or "tam o shanter" urchins. You can see more about them here (with links therein). 

Basically, these are soft-bodied sea urchins which often have poisonous spines and little walking legs.

But the ones we saw on this peak? just ENORMOUS.

The lasers are 10cm across,(about 4 inches)..so, okay this one is only about 8 inches across

but we panned across to another ledge and found a few more...

This darker brown one ended up being about 2 laser lengths..so about 8 inches across! that's basically the size of a small pumpkin! do they get bigger?

Wikipedia lists the "largest" species at 14 inches (36 cm) but did not elaborate on species..(will need to check). But if that's the upper limit, then 8 inches is definitely monstrous!

5. A deep-sea... NUDIBRANCH??
This one was quite a surprise, because I had largely thought that sea slugs were limited to relatively shallow depths, much less PROPER nudibranchs which are overwhelmingly found in nearshore settings.

This looked pretty bigh on camera and was about 5 inches long? when we collected it..

Amazingly, there is one genus of proper nudibranch in not only the Antarctic but in the deep-sea: Bathydoris!  I'm not sure quite yet what they eat but will find out!

Colleagues at the Monterey Bay Aquarium Research Institute apparently saw this species, Bathydoris aioca at 3000 or so m in Baja California in 2012! 

How will the species we collected compare??? Stay tuned! (and thanks to Vanessa Knutson for her help with the ID!)

From pic I don't see rolled rhinophores & appears to have dorsal gill rather than side-reminds me of Bathydoris but w ex long ant. papillae!

— Vanessa Knutson (@Bugs_and_Slugs) July 27, 2017

That's a quick recap of some of the non-sea star events..but I'll post more as opportunity permits!  THANK YOU to the crew of the Okeanos Explorer, NOAA and my science team colleagues for inviting my participation!

Echinoderms with Spines for Walkin'

OKEANOS Explorer is BACK!!! And even though they've only been able to venture into the field for two days, there's already some AWESOME video which inspires this week's post!! 

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!!!

Do you see those round, circular tips that are on the tips of the spines??

Look at the red arrows below pointing to the "walking cups" on the spines that the urchin uses to move!

What's also kind of interesting is that this animal (and I think a few others) were actually CLIMBING a rock face and not just walking along a flat surface as diagrammed by Mortensen back in the day. So, these do a lot more than just just support..

Think of the spines like the long legs on the spider robot from Johnny Quest!

The "walking tips" of the spines look sort of like little hooves that the spines use to gain purchase on the substrate probably in conjunction with the tube feet. The center illustration shows what the bottom of that "hoof" looks like as you look directly up into it.. basically a modified spine tip adapted to aid in movement!

So, we HAVE seen something like this before in  Echinothuriid or "tam o shanter" or "pancake" urchins! 

I've done this story more than a few times..with one of the most recent accounts here.

Long story short: The urchin walks on a bunch of little legs with modified tips that ALSO resemble hooves! 

Look for the little white tips on the spines around the bottom edge!! Those are how it moves around on the soft-muddy substrate.

Here's a close up of what those look like!!! Superficially similar to the ones in Aspidodiadema!  At least in shape..

But wait.. There's MORE????   How about in STARFISH???

That's right! I'm pretty sure I've found spines that might serve in a similar (or maybe opposite?) fashion in deep-sea sea stars!  The filter-feeding Brisingids!! (here)

I just published a paper last year which documents some work I did recently on Hawaiian brisingids!

The starfish actually live on old munitions and junky metal debris.. I wrote about it here

Among one of the discoveries was a new species of the brisingid genus Brisingenes in Hawaii! Scientific paper citation is here.

The species was named Brisingenes margoae in honor of Dr. Margo Edwards at the University of Hawaii! She is a professor of geophysics working on mapping this unusual munitions filled terrain! 

She was head of the project and invited my participation! 

After collecting these starfish I noted something rather interesting.. the tips of the spines that occur on along the tube foot grooves were stained brown from contact with the metal casings they were sitting on! 

The one on the right shows the brown tip on one spine..

 This suggested that these were actually inset or even anchored into the surface rather than just kind of pointing away as has been suggested from watching them filter feed..

But when you look further at some other species, you see that there's probably an additional way for them to remains stabilized on whatever bottom they happen to be sitting on..

Here's a close up of some of those spines in one species from the North Pacific.. The tips are kind of wide and hoof-like! Similar to what you see in Aspidodiadema and the echinothuriid urchins! 

The case for the functioning of these spines is still sort of at the "hypothesis" stage at the moment..but it seems like a good argument all things considered. It seems likely that they serve at least in part as anchors. But do they use them to move also? Little walking legs? Something in between? Do they vary depending on where they live?

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!!

Paris! Urchins in Abstract!

This week: more showy echinoderms from one of the greatest museums in the world! Paris! Here's another study in abstracts-focusing mainly on sea urchins!

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! 

Alien landscapes? Weird colors? Vs. Spines, mouth plates and sea urchin skeleton! Enjoy!

The duo colored spines of the urchin Salmacis! 

The "teeth" of a "pancake urchin"

Oral spines on this cidaroid urchin. Yikes!

The naturally orange colored spines of this cidaroid (Compsocidaris?)

Natural green and purple stripes on these urchin spines!

More green and purple colors on this cidaroid urchin!

The large crazy spines of Goniocidaris and what lies beneath! 

Know your Deep-Sea Urchins! (Okeanos echinoid edition!)

Leg 4 of the Hohonu Moana Okeanos Explorer Expedition has begun! (here is the link to live feed!)

We have new investigators Scott France (on invertebrates) and MacKenzie Gerringer (on fishes) studying the huge diversity of deep-sea corals, sponges and other life in the northern Hawaiian Islands region.

The Hawaiian region brings with it a very different fauna from the one we saw in the Atlantic Okeanos cruises. There's actually quite a bit more diversity in the Pacific in sea stars, and many other echinoderms. So I thought I would offer a guide to some of the more prominent groups of echinoderms that we are likely to encounter in these deep-sea habitats: the sea urchins!!

Most everyone is familiar with the spiny balls that one observes in the intertidal or while SCUBA diving. 

And basically, sea urchins in the deep appear the same.. BUT many of them are unusual in some way.  Different adaptations or different evolutionary histories and there's much more to them than the "typical" urchins most people encounter in shallower depths. 

Here are some of the more commonly encountered sea urchins we will likely encounter in the Hawaiian region (below about 1000 m). These are also pretty typical of deep-sea settings throughout the Indo-Pacific.

There ARE a few that aren't noted here. Mostly the "irregular" urchins such as sand dollars, or sea biscuits. 

My thanks in advance to the Facebook screengrab group and Carina M. Gsottbauer

1. Aspidodiadema:  This is a genus of unusual deep-sea urchins that is represented in Hawaii and in many tropical deep-sea habitats in the Pacific as well as one species in the Atlantic. These have really long spines that it uses for locomotion in conjunction with its tube feet.

There's apparently more than one species of Aspidodiadema in Hawaii, but so far we've been calling the one seen by Okeanos, Aspidodiadema hawaiiense. Upon looking at both images, there do seem to be some differences but its unclear without a specimen to examine..

Here's a nice moving GIF of this Aspidodiadema species on the move! 

Rewatching yesterday's #okeanos dive: sea #urchin moving slowly (Aspidodiadema hawaiiensis) #Hawaii, Lone Cone ~2060m pic.twitter.com/jDatlCvp7S

— Carina M. Gsottbauer (@CarinaDSLR) September 22, 2015

This image shows the same type of animal as the one above but with a mysterious bag like extension emerging from the top. Possibly an anal sac as we see in diadematid urchins?? Unclear.

In comparing them, this second one seems to be lighter in color... 

2. Caenopedina! This genus is a member of the family Pedinidae, of which it is the only living member. This genus is widely occurring mostly in deep-sea habitats. 

According to the Hawaiian Undersea Research Lab's Animal ID guide, there are two recognized species in the region: 

Caenopedina pulchella This species shows these very thick spines which are brightly colored green and purple!

The small individual above seems to have much smaller spines relative to this larger one.. but the colors patterns appear consistent..

This second species is Caenopedina hawaiiensis and it seems to show a very different appearance... 

3. Echinothuriid Urchins! These are one of the most frequently encountered sea urchins in deep-sea settings. Commonly referred to as "pancake urchins" or "tam o shanter" urchins, their body shape is suspended by water pressure, so when removed from the ocean into say, a bucket on the deck of a ship, their very soft skeletons collapse into a flat "pancake" like shape.

I've written on these animals plenty of times here and here and their shallow-water relatives here. 

One caveat about this section: I'm not sure that any of these can be correctly identified..so I'm keeping it vague. At least for now. 

But salient features of the urchins as a group include: 

1. Needle sharp spines which can be pretty dang painful!

2. Cute little walking legs with special "hooves" on their spines 

We've seen at least 2 species.. this purple species..

Rewatching yesterday's #okeanos dive: sea #urchin w/ mittens on its spines #Hawaii, Lone Cone ~1800m pic.twitter.com/kEL4cTtBIn

— Carina M. Gsottbauer (@CarinaDSLR) September 22, 2015

There's this slightly different pink echinothuriid

 this grey species                            

Echinothuriids are a frequently encountered group in the deep-sea. We will likely encounter more of them..

4. Cidaroid Urchins! One of the other "typical" urchins one encounters in the deep-sea is that cidaroids.  This is a fairly old group of urchins, which branched off early in the history of urchins and has a fairly good Mesozoic fossil record (see here).   

Cidaroids are unusual for urchins in that they lack skin on their spines, which results in an overabundance of "fouling" animals which can settle and grow on them. I've briefly talked about the ecological importance of this here. 

We've also seen cidaroids with a CRAZY range of spine shapes and morphologies, such as what I summarized here. 
                           
Cidaroids are not just predators on corals as shown below, but are also likely predators on stalked and other crinoids as I've posted about previously..

A nice diversity of cidaroid urchins in the deep-sea Hawaiian Islands.. More at the HURL gallery here.   but sadly we've really only seen a few at the deep depths Okeanos has been exploring..

Histocidaris variabilis.. note the barnacles growing on the spines...

Stereocidaris hawaiiensis

Possibly Stylocidaris calacantha.  This one was observed high up in the branches of this bamboo coral, likely feeding on the polyps..