Wednesday, May 4, 2016

Five IMPRESSIVE HIGHLIGHTS from the Okeanos Explorer's Marianas Expedition!

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.

Remember that the live video is broadcast here (via Youtube). The live broadcast begins fairly late if you are on the east coast, but usually around 5 or 6 pm.

You can also find many of these images from screengrabs on Twitter using hashtag #Okeanos or go to the Facebook underwater screengrab group 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!



3. Likely New species of Carnivorous (Cladorhizid) Sponges
Probably some of the most commonly encountered animals on the Pacific Okeanos expeditions have been sponges (here for more). Chris Kelley at the Hawaiian Undersea Research Labs has mentioned that there are easily two dozen new species of glass sponges currently being described with more apparently being discovered!

But one of the more unusual sponge species discovered on these cruises are those in the family Cladorhizidae: enter the CARNIVOROUS sponges!!  Although they've been known to scientists for awhile, they only recently entered the public eye after the famous "Candelabera sponge" was discovered back in 2012. 

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."

Animals with similar morphology are well known from VERY old rocks (back to the Paleozoic) go here. And although these modern forms are different from those fossils forms, they DO share a certain similarity.

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 region and 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!

Some of the more striking deep-sea species were recently presented by the Monterey Bay Aquarium Research Institute back in 2011! see this) One Atlantic species of these worms was actually named for Star Wars Jedi Master Yoda! based on the large "ears" (actually genital flanges!) 

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! 

Tuesday, April 26, 2016

The Diversity of Echinoderm Anuses!

Juvenile urchin
This week, in the category of "one of those posts only Echinoblog could write"! Let us explore the vibrant diversity of echinoderm anal structures!! Perfectly SAFE for Work! even though it contains the word "anal" and "anuses" several times! WOO!!

Echinoderms are pentaradial (aka pentameral). That is they show a form of radial symmetry wherein their body always occurs around a top-down axis in five parts (although arms, etc. may vary).

As a consequence, the overall dynamic of their life mode is different from an animal with bilateral symmetry. No face, no "front" or "back". Thus, the way food moves through the body is different depending on where the mouth is located and consequently, where the anus is located!!

Since each living class of echinoderms has a fairly unique shape and body morphology, each group has a bunch of unusual specializations that function to facilitate the expulsion of poop!

To be honest, not every member of each class below has what is shown below. These are unusually prominent examples..but it still begs the question "What is it used for?"  How many other animals have so many unusual anal adpations??

5. Crinoids: Anal Chimneys & Pyramids
So, crinoids are suspension feeders. They almost kind of resemble plants. Most living ones are known as "feather stars" and are basically cups with arms for filtering water. But earlier forms of crinoids are known as "stalked crinoids" which have a stalk. I had a gallery of the older Paleozoic ones here a few weeks ago..

Here's a living one from the recent Okeanos Expedition to the Marianas region to give you an idea of what they look like..

So, the mouth in stalked crinoids is inside that cup at the base of where all those arms converge. The anus for these animals is ALSO in the cup. So, there's likely a strategy/adaptation for these animals to push the poop/excreta OUT of the anus, such at it does not end up getting "re-eaten" by the mouth...

According to Fossil Crinoids by Hess et al.  there were several fossil (Paleozoic) forms which had fairly straightforward strategies for dealing with ensuring that poop was discharged FAR from the mouth..

For example, here is the Mississippian Uperocrinus nashvillae with an explanatory diagram from Fig. 37 of Hess et al's book. Basically that huge pointed structure on top? That's called the anal tube  (or sometimes in other animals.. an anal pyramid or even an anal chimney!)

These extended structures serve to project the anus (and the excreted poop) well AWAY from the mouth (the feeding arms would come off right at that wide "ledge" around the center of the specimen..



There was a surprising diversity of these structures. Here's another one called Macrocrinus verneuilianus which is a fossil from the Carboniferous (the Paleozoic). The drawing below is taken from the Wooster Geologist blog and they point out that the elongate anal tube (in the lower left hand corner) aka the anal chimney may have even served an additional function beyond simply transporting poop away from the mouth:
The tube allowed waste products to be whisked away far from the mouth of the crinoid, which was at the base of the arms. Some researchers suggest that the long tube served another function as well: it may have helped stabilize and direct the filter-feeding fan of outstretched arms in a stiff current, something like the tail of an airplane or a panel on a weather vane.
Macrocrinus mundulus, Macrocrinus, Batocrinidae, Monobathrida, Crinoidea, Echinodermata, Deuteriostomia, Bilatera, LOCALITY- Montgomery Country - Indiana - USA, CARBONIFERO,

One last weird crinoid is this one: Bicidiocrinus wetherbyi
Another Mississippian (i.e Paleozoic) stalked crinoid.. and this is kinda weird. So, there's the cup and the arms and that cone is the anal cone (=tube, pyramid, chimney, etc.) BUT it also has this weird additional protective "spiniferous canopy" around it!!

The diagram on the right shows this fully "reconstructed"..

and the reconstruction from Hess et al. Fossil Crinoids-which is a GREAT book for these useful facts!                              
Ultimately, there is probably a WHOLE blog post or 5 about Paleozoic crinoids and what we know about their paleoecology.. I briefly touched on the snails that parasitize their anuses here.... 

One LAST MINUTE ADDITION: David Clark (@clarkeocrinus) provides this ASTONISHING Proteriocrinus with a very considerable anal chimney!! which looks to extend nearly the length of the cup and arms!
4. Sea Urchins: (Diadematidae) Anal Sac
Probably one of the best known but most poorly recognized of the various echinoderm anal structures is the ANAL SAC in diadematid (diadematoid?) sea urchins.

This includes Diadema, Astropyga, Echinothrix and all of urchins in this family. Usually these are tropical and characterized by long, sharp spines AND a very distinctive "anal sac" present on the TOP of the body.

The problem is that many people see this big eye-shaped ball on the top of the sea urchin body and assume that it is an eye of some kind...
Echinothrix calamaris urchin ind12b 0149
I can tell you most DEFINITIVELY that this structure is NOT the eye. I actually explained in great detail here how this was actually the unusual ANAL SAC which is characteristic of this type of sea urchin for an error in New Scientist.

That said, they DID publish a WONDERFUL picture by David Fleetham of Astropyga radiata venting poop OUT of the anal sac!!

Basically, this is a transparent or translucent bulb or sac extension from the anus through which feces passes on its way out of the body.

See those little round things that look like corn kernals? Sea urchin poop!
Here's another great pic found on Flickr, taken by Eunice Khoo of what looks like a small Astropyga sp. clearly showing poop THROUGH the transparent walls of its anal sac (aka anal cone).. 

Very nice capture. 
Juvenile urchin
But why take my word for it??  Go ahead and watch it here in this video of what looks like either Diadema or Echinothrix..  The poop event takes place at about 0:15 into the video.
               
But its not JUST shallow-water diadematid urchins that have this anal sac. Here's a deep-water Aspidodiadema from the recent Hawaiian Okeanos expedition. I talk a bit about these here

These were videos of these animals from 2000-3000 METERS below the surface. Aspidodiadematid urchins are classified in the same general group as diadematids. and they too seem to have this anal sac or cone...

3. Ophiuroids: Alas..brittle stars got no anus. In fact, food goes in and goes out the SAME hole: the MOUTH. So..bummer.
Brittle star oral side

2. Anal (or Epiproctal) Cone
Sea Stars/Starfish in a larger group called the Paxillosida (the mud and/or sand stars) have a specialized structure which sits right on the center of the disk called the anal or epiproctal cone.

A brief anatomical note- Although historically called an "anal cone" these starfish don't actually have a complete gut and so, the opening on the disk center is not actually the anus since it doesn't connect with the interestine. Hence the name "epiproctal":  EPI is Greek for "upon" and PROCT is Greek for "anus".. hence the cone or structure UPON the anus..
The cone is basically an outpocketing of the body, extending UPWARDS through the sediment
From (Fig. 2 from Shick 1976)
To quote myself from a few years ago:
Observations of Ctenodiscus under hypoxic conditions led to the illustration above. Basically, its thought that the cone gets more enlarged as hypoxia and hydrogen sulfide increases. The extension of the cone extends through the surface, with the tip at the surface. For your typical 6.0 cm diameter animal, these animals can have a cone that can attain 3 to 4 cm and extend 2 to 3 cm above the mud. It can leave this extended for over an hour. As the picture suggests, it can move around and push through sediment as the mud shifts, and etc. So, it can move around.
This also serves to make the top surface of the animal thinner, allowing easier gas exchange and opening up a channel to the surface water above the sediment surface!!
From Shick 1976 Marine Biology: http://link.springer.com/article/10.1007/BF00387613#page-1
So, in truth, the "anal cones" in these mud stars is NOT really an anus. Its where the anus would be located in other species..and so the labelling of this stucture is kind of a misnomer.. as they are not really used for defecation.

Other "mud stars" such as this deep-sea (3000-6000 m) Porcellanaster also have well-developed "anal cones". These starfish sit buried in sediment with these projections sitting up through the sediment. 
In contrast this shallower water Astropecten armatus has a much less developed anal or epiproctal cone. This is also related to the fact that it occurs in shallower water and tends to bury itself in somewhat less sediment compared to the above two species..
from CSU Fullerton: http://biology.fullerton.edu/biol317/ftm/ft_s15_cat_4_25_15.html

1. Sea Cucumbers (Holothuroidea): Anal Teeth
And finally, one of the best known of echinoderm anal defenses: the anal teeth in sea cucumbers!

I've reported on these before. There's at least one interpretation that these structures are defensive in nature and work to keep pearlfishes (and likely other commensals or parasites) from inhabiting the cloaca.

There's quite a few crabs and shrimps that live in and around sea cucumber anuses. See more here.
Sea Cucumber Anus

Sea Cucumber Anus

Sea cucumbers get kind of a special award for using their cloacal and other "ass end" chambers most efficiently..especially since some species can actually FEED and BREATH as water passes through the anal opening!! Read more about that here.
DSCF2985.JPG

So there you have it! The Astonishing Anuses of the Echinoderm World!