Wednesday, September 21, 2016

Unravelling the secret diversity of Psychropotes! A global sea cucumber mystery!

via the NOAA photo library
Today we look at one of the most bizarre deep-sea echinoderms (if not deep-sea ANIMALS) that I know of! the sea cucumber Psychropotes!!  I briefly discussed these in an earlier post on deep-sea sea cucumbers.. but have not had the pleasure of writing something up about them in detail..

Here's some video to give you an idea of what it looks like/how it moves, etc. (I would watch without sound to enjoy the zen of the animal)
IF the name doesn't sound familiar, the animal's distinctive appearance definitely stays glued in your head after you've seen one! Imagine a big blobby sea cucumber with what looks to be a HUGE LOBE sticking out of its hind end!

Note the image above contrasted to this diagram showing mouth (top) and anus end (with lobe-bottom).

The genus Psychropotes is derived from the Greek for Psychros which means "cold or frigid" and "potes" which honestly, I could not find a definitive translation for...   One root translated to "flight"? possibly alluding to the ability of this species to swim...And another colleague tells me it might mean "dweller". Ah well, one mystery at a time!!

Psychropotes includes 11 species which occur widely, all around the world in the Atlantic, Pacific, Indian and Southern (but not in the Arctic) oceans in the deep abyss of the world's oceans! That means roughly 2000 to 6000m. They are the deepest of the deep! Considered "classic" deep-sea inhabitants they were collected and described from the HMS Challenger's historic mission.

These can be pretty BIG animals!! as this image from a recent MBARI expedition demonstrates. (with deep-sea biologist Greg Rouse for scale!)

But there is ONE species in particular, P. longicauda (the species name "longi-" means long and "caudex" refers to 'trunk or stem" and alludes to the posterior lobe in the same way that caudal fin refers to the end of a fish) that is of interest.
Individuals all identified as this species, P. longicauda have been observed from oceans all around the world and varies rather widely in many ways. Sea cucumber species are identified based on tiny calcite bits called sclerites which seem to be highly variable.. with differences in sclerite shape varying between different regions.  But do all of these differences amount to different species?  Or variation within ONE species?? 

Here for example was one seen from the recent tropical Pacific Okeanos Explorer cruises. Note that the "lobe" is a different shape. Separate species? Damage? 
This turns out to be a pretty important question to deep-sea biologists. Can there be ONE species present at such a huge scale? Or are there species present that are CRYPTIC or hidden from us by body characteristics alone???

Note the one above with the shorter, forked "lobe" Is it the SAME species as the purple one shown earlier? Is this variation? (such as what we might see in humans who live in different parts of the world) Or are these separate species?

Their study explored the widespread occurrence of this species based on 128 specimens of Psychropotes longicauda collected from THREE different oceans over a 34 year period, from 1977 to 2011!
This represented an INTERNATONAL team of experts from not only the University of Southampton in the United Kingdom but also the Shirshov Institute of Oceanology in Russia, the American Monterey Bay Aquarium Research Institute (MBARI), Scripps Institute of Oceanography and many, others!! 

They sampled tissue for two genetic markers (COI and 16S for those who need to know) across all the sampled individuals in order to compare populations from all around the world. 

The Global Colors of Psychropotes
So, here's the result. Scientists use diagrams to show a basic outline of relationships between different populations. Roughly speaking, the greater the distance between the circles the larger the distance between the populations and the greater chance they are separate species...

In the first diagram, the LARGER the circle, the larger the sample size. So the bigger circle represents the largest number of samples. Which were all from the Atlantic Ocean.  

Note the helpful color key so you can tell apart the populations you are seeing below:

Dark Blue= North Atlantic (east)                      
Light Blue= North Atlantic (west)
Yellow= South Indian Ocean
Green= South Atlantic
Red= Northeast Pacific 
Dark Purple= Northwest Pacific
Pink= South Pacific                                                                                               
Their figure 2 here shows what is basically the number of "steps" away from one another each population happens to be... The size of each circle represents the sample size. The big patch of BLUE reflects the LARGE sample of ATLANTIC specimens..but note how they are all clustered together. 

Some closer, some farther away.. This means they are all more closely related to one another than to those the others.  But note how many different subgroups are present away from the big blue circle in the middle?  That suggests lots of 

The Red (Northeast and Northwest Pacific) therefore seem to display a somewhat closer relationship to those in the North Atlantic than to those in the Southern hemisphere (yellow, green, pink, etc.)
Figure 2 from Gubili et al. 2016
Their figure 3 below, shows all of the populations in more of a "family tree" (i.e. phylogenetic), not only do we see that all of the Atlantic and Pacific members are "close" but they all occur on a single lineage, which means they were all MUCH more closely related

Two major lineages are most evident in the phylogenetic tree below, Lineages 1 and 2 each with subgroups:  Lin 1A, Lin 1B and Lin 2A and 2B, respectively. 

The pattern is kind of unclear..but there's definitely an Atlantic cluster (Lineage 2) with members that occur in the Indian and Pacific but this seems very separate from the Lineage 1 which seems to include members from all over, including the Indian Ocean and the South Pacific.

Figure 3 from Ghibili et al. 
Ultimately, the two lineages (Lineages 1 and 2) showed > 5% divergence from one another. When compared with other echinoderm species, that much population genetic divergence is enough to recognize a separate species (as opposed to simply a population with structure).

So, YES. One lineage, is the "proper" Psychropotes longicauda species, but there's at LEAST one more which has been "hidden" by the taxonomic definition of Psychropotes longicauda. That is, they all LOOK like the described species but in fact, the differences are FAR more subtle than we had previously recognized! More diversity (i.e., further species) will likely be discovered as more data is collected..

Some of these further subgroups will be so-called "cryptic species" because morphology does not immediately distinguish them. Thus, their status as species is "hidden" by external morphology (but subsequently discovered by genetics).  But now that we are looking, many, MANY more characters that could help distinguish these species could conceivably be discovered.

Other Interesting Observations/Questions..
One interesting factoid was that Psychropotes, and many other deep-sea sea cucumbers only occur in areas of high productivity (i.e. marine snow). Could these nutrient rich regions be related to speciation? and diversity within the species? 
The authors were able to note changes in the genetic diversity and abundance of the Atlantic lineage across a temporal series! Based on the extensive collections at the National Oceanography Collection at Southampton University, they they observed an uptick in the abundance of small individuals but also a change in the amount of genetic diversity  in relation to an increase in organic flux called the "Amperima Event" in 1996!

They found that there were MORE individuals which belonged to the "Atlantic population" and fewer of those which shoed affinities to other oceans. This might explain why the Atlantic "genetic type" was so well established.  They cautioned that although they didn't have enough of a dataset to show changes over time, they DID say that there WERE changes in the genetic makeup related to the nutrient availability. 

That is a pretty snazzy thing to record from a collection of deep-sea sea cucumbers! 

Is there an Antarctic origin for Psychropotes longicauda
The authors argue that the combination of Southern Indian Ocean lineages was consistent with other hypotheses arguing for an Antarctic origin for this widely occurring deep-sea sea cucumber. 

Repeated colonization events from the Antarctic via the Southern Indian Ocean (yellow colored in the figures above)  might explain the many lineages of Psychropotes present throughout the world's oceans as well as the presence of multiple lineages of Indian Ocean Psychropotes versus the derived and consistent clustering of Atlantic and Pacific populations.

(Coincidentally this picture of a Southern Atlantic Psychropotes is yellow!! )

What further mysteries does Psychropotes have in store? I anxiously await the next paper! if I could only figure out what the "potes" part of Psychropotes means!
And just because, here are some FANTASTIC Psychropotes Bonuses! 

Here was an AWESOME Psychropotes cake by Elizabeth Ross, one of the authors of the study...
And of course Psychropotes stuffed animals.. from Japan of course!! 
from ebay

Wednesday, September 14, 2016

Taxonomy: Lurking behind all the Big Announcements!

GREETINGS! And my apologies for the long silence over the last few weeks: a little bit of time to recharge the batteries and a little bit of frantic insanity as the fall began! So, this week I am back!

There's been a fair amount of news about taxonomy lately, so I thought I would embellish with some "behind the scenes" knowledge that might not have been evident simply from the news reports themselves...

Scientific Names vs. Common or Popular Names: What's Required
Just so that we're all on the same page, here's some general information about the naming of new species.

There are actually a set of internationally recognized CODES (i.e. rules) for describing species and governing their use. These codes are overseen by the International Code of Zoological Nomenclature (here) and although they are not much more than a regulatory organization, they do try to keep everything from going taxonomic kablooey!

Basically, it is these rules that dictate HOW a lot of organisms in the world get scientific names. So, simply SAYING that a new organism is called "A blue Baboo Fish" won't cut it. It actually has to be supported by evidence and published in a PEER-REVIEWED journal and given a proper scientific name in the proper format (in Latin, etc.). ONLY THEN is such a name considered valid.

Common or popular names (e.g., "blue tang" or "cushion star") have their uses but ultimately, scientists depend on the specific context of having a unique identifier associated with a particular organism. Mainly because common names are EXTREMELY variable. I've talked about the insanity of the term "cushion star" here before..

BUT a number of other rules are also at play in order to keep the process of naming new species orderly...

Nomen Nudum aka Why we don't know the name of the President's Fish (yet!)
Have you ever noticed that there's often a significant time lag between the time someone ANNOUNCES that they have DISCOVERED a new species and the time that new species is ACTUALLY described??

That's because the name is not "official" until it is actually published in a scientific journal. If for some reason, the name is actually published before the proper scientific documentation is released to accompany it, the name becomes what is called a nomen nudum which is Latin for "naked name."
So, for example, many probably saw the news that there was a fish species named in honor of President Obama (here), who dramatically expanded the Papahānaumokuākea Marine National Monument.

Note that while some accounts actually went so far as to cite the genus name (Tosanoides) nowhere will you find the FULL name until its published in the literature.  Is it a liberal conspiracy? NOPE. Its Taxonomy!

If they actually announced the full species it would create a nomen nudum, which is kind of like the taxonomic equivalent of a time-space anomaly from Star Trek. That means there's a proper scientific name flying around WITHOUT a proper scientific description.

When written out completely, the full format of valid scientific names display a reference to the original author and date of the paper which described it. Thus, the full name of one of my species
"Circeaster arandae Mah 2006" refers to a paper in 2006 in which I described the species Circeaster arandae.

Getting back to the nomen nudum however, Note  that this does not necessarily invalidate the name. But it does open the name up for other unscrupulous (or unknowing) individuals to inadvertently use the name, thus "taking away" the name from the author's original intent. (or in the worst case, stealing the name from the original author).

Another real example...
You might have seen this little guy for example. A new species of dumbo octopus that one of my colleagues Stephanie Bush is working on out at MBARI/Monterey Bay Aquarium. 

In an interview she alluded to the fact that the animal is SO cute that she might call it "adorabilis." She called it that informally as part of an interview but the media took the name and pretty much made it stick.

SO many news outlets have now used this name that it has turned up everywhere..but it has NOT been described or published in a scientific journal as of this date (Sept. 2016). This is not strictly a nomen nudum but conceivably, someone might mistakenly cite it in a scientific journal somewhere.

If that happens, then BOOM. It has entered the literature. This still does not mean that Dr. Bush cannot use the name..but it DOES mean that if someone else happens to use the species name "Opisthoteuthis adorabilis" that will "steal" the name away from her because ANOTHER scientist will have justified a species using that name in compliance with the ICZN code..

If by chance the name was published TWICE and in proper compliance by BOTH authors then a new situation arises. In that case the name published first has priority... A great segue into a discussion of SYNONYMY...

Synonymy aka Why you have to be careful if you "bought" a new species

Probably one of the most important of the codes in the ICZN is that of "priority" which basically states that the OLDEST (i.e. the FIRST) name established for a species is the correct one. All subsequent names of the SAME species are essentially considered redundant and their use is suppressed once that assessment is made (but there are exceptions on occasion-better explained at another time).

That seems pretty straightforward.  But in truth, it can get pretty unfairly brutal.

There's a LOT of new species that are named in "good faith", sometimes even with very strong data that for whatever reason are ultimately deemed to be "redundant" and are suppressed in the literature.

So that means if someone described a new species with a shoddy (or in some cases, almost NO details)  description-but it was ADEQUATE, followed by a second description that was just an objectively BETTER account, that FIRST author gets credit and the other species get put into the list of "redundant names" aka the synonymy.

While this consideration is always important, one of the biggest trends this becomes relevant for is the "Buy a new species name" thing that has been done recently to raise funds for further research, or otherwise charitable causes...  Scripps Institute of Oceanography advertised the honor of naming a new species for $5,000 (see worm below as an example) whereas other places have gone over into bidding wars over $7,200!   This ebay auction won the rights to name this new species of moth for $12,600.00
So, someone who is NOT a scientist can easily get the rights to name a new species or even name a new species AFTER you as a gift....but its always possible that the name you give it, whether your own or someone else's, could eventually be synonymized by another person in the future because of some unknown specimen or just better understanding of the species in the future. 

Now, granted, there tends to be LESS of a chance of that happening depending on how much work the scientist doing the work has done and depending on what kind of data supported that new species in the first place, especially with molecular data.

But its STILL possible, sometimes even if nothing was done wrong... Science is an ongoing process and although taxonomy has kind of a reputation for being a bit stogy the truth is that it IS quite dynamic and taxonomic changes are common place (much to the annoyance of those who use species names!)

Can you name a new species from a picture?
Okeanos Explorer is a research vessel operated by NOAA that broadcasts LIVE streams of its deep-sea research over the internet. I'm one of the "shoreside talent pool" which answers questions from the scientists on the ship AND from the public. (see #Okeanos on Twitter for some of my live-tweets from the dive).

A question that came up recently from my last Okeanos round, was whether or not a new species could be described ONLY from a picture or video rather than a specimen???

Uh.. No and yes.

For MOST (nearly all) cases, some kind of voucher is necessary. Why? Because we require EVIDENCE to describe a new species. Measurements. Observations of the skeletal (or non-skeletal) structure. Analysis of different features. DNA. Any one of thousands of kinds of data which permit us to carefully contrast the known species of organisms from one another.

At the very least, a specimen must be examined so that we can carefully discern why its gross morphology is different from other similar species. These specimens are conserved. They are saved in museums for future generations to reference and retained for hundreds of years.

HOWEVER. In some RARE instances, there IS an allowance for new species to be described ONLY from a picture. It used to be invoked for exceptional cases-rare and endangered species for example.

But just a FEW months ago Neal Evenhuis at the Bishop Museum in Hawaii made the case that in some cases, a photo ALONE is enough to describe a new species-given PROPER evidence.  (Scientific paper is here)
We live in an era with increasingly high-resolution imagery, sometimes SO good that even the minutest details can be made out without physical examination. Millions of images of a biodiversity survey can be brought back on a drive the size of a large coin.

The octopus seen by Okeanos was identified because it was an "incirrate" octopus (as identified by NOAA researcher Mike Vecchione) which had NEVER been seen at that depth before. Almost certainly a new species

The conservative scientific approach in publications would be to indicate it IS a new species but without a proper name (e.g., Octopus n. sp. 1)

BUT it can't be properly characterized because a LOT of octopus characters are internal and require direct comparison (unlike the South African bee example above which COULD be identified and characterized).

Also, while unlikely, its POSSIBLE that there is a specimen of this animal somewhere in a museum somewhere in the world which has already been published.  Without reconciliation of all these disparate factors, one risks creating redundant names which are essentially permanent and creating possible confusion.

Thus, identifying a species directly from ONLY a picture would be more direct but not as thorough and does not give us enough data to properly assess it. But yes, there are exceptions.

Identifying species only from pictures also invites the possibility of abuse and reckless taxonomy which could impede and hopelessly confuse the work of legitimate scientists during a time when there is a dire need for workers to be be studying Earth's biodiversity...

Species named after celebrities & pop culture? What's up with that? 
Scientific names as outlined in the Zoological codes are always supposed to be in Latin. A dead language that nobody speaks any longer. This used to be a scholarly language that was widely used among educated people.

This also made scientific names pretty straightforward. I've documented the word origins of MANY starfish species before (such as here)   Some make great stories in and of themselves 

Most scientific names are based on descriptive terminology. So, for example, the name Acanthaster , which is the scientific name of the Crown of Thorns starfish (learn more about this genus here), literally translates into "thorny star" from the Greek acanth- and the Latin -aster meaning star. Many of these names were sort of an open book...
Crown-of-Thorns Starfish
But there has been a LONG tradition of naming species AFTER people, places and things to honor them. Both genera AND species. Some of the oldest and best known genera are named for the "noted scientist of the day", for example Luidia-the starfish is named for Edward Lhuyd who called himself Luidius.

Although you would think that naming a genus would be better than a species (because a genus is higher up in the taxonomic hierarchy), in fact, its not. Higher level names tend to be made into synonymies more frequently than species. Species tend to stick around for quite awhile longer..

It USED to be that many of these names would stick to people known to the scientists: wives, children, close confidants and good colleagues and certainly this continues to be the case. I've named MANY species after close friends and colleagues.

As we have gotten into the 20th and 21st Century however, we NOW see increasingly the role of pop culture influencing taxonomists! There are a number of reasons: Some think it makes taxonomy more relatable, some have found genuine inspiration from popular entertainment, others have many MANY species and have just "run out" of Latin names.. an endless list from a huge pool of scientists.

Sometimes the people/characters as names are directly influential!   As with Yoda above. the genital flaps of that acorn worm (an enteropneust) were VERY reminiscent of Star Wars Jedi Master Yoda! The ICZN is actually surprisingly flexible in allowing for "translating" terms into taxonomic names... And hence its namesake! From a character created in the late 20th Century into an ancient dead language! No problem! (if you know how)

We have flies named after Beyonce, wasps named after Shakira and trilobites named after Mick Jagger! You can see a full list of names here on Wikipedia.

and of course the brittle star named after George RR Martin of Game of Thrones! 

Taxonomists are diverse. No longer done by ONLY classic stodgy, out of touch scientists-but hip, trendy nerds as well! .. it is done by many students and dynamic individuals who follow popular trends.. and we will likely see more and MORE of these pop culture names in the future....

thanks to Monica M. who asked me the question about Obama's fish! that inspired this post.

Tuesday, August 23, 2016

Gorgeous Closeups of Australian Starfishes!

Seastar Detail - Bateman's Bay
Greetings! This week, I thought I would share some GREAT closeups of the textures and plates on some sea stars from one of my favorite places in the world-AUSTRALIA! 

These were all taken from images on Flickr, and so the original photographers can be found merely by rolling over the image itself. What's great about them, is that the images were taken from LIVING animals, and so their colors remain vibrant! Nothing here is photoshopped.

Contributions herein by photographers:  Bill, Tony Brown, Beth Heap, Leander, Richard Ling,  Lox Pix, Morley Mason, Andrew Newton, Matt Nimbs, Valguille and especially SASpotato! 

An asterinid, Patiriella I think?
Asteroidia | Asterinidae | Patiriella calcar [Variegated Sea Star] - Flat Rock, Ballina, NSW
Cushion-star  Patiriella calca
They look knitted
Here is a close up of the papulae or gills on Plectaster decanus 
271104 Seastar Close-up Long Bay
Mosaic Starfish
The rest of the animal looks like this. Gorgeous.
Mosaic Sea Star
Some goniasterid beauties! Pentagonaster dubeni
Steps Red Seastar
Pentagonaster pattern
Lovely plate architecture on Tosia australis
Biscuit star detail

From above, these are the surface plates of the goniasterid genus Nectria
Seastar Detail - Bateman's Bay
Any guesses what these are?

and here's what the rest of the goniasterid Nectria looks like!
image by Peter Southwood, via

A stunning yellow one!

The very distinctive button like plates on Asterodiscides sp. 
Firebrick Sea Star
and from the same animal, the large penultimate marginal plates, which are distinctive of the genus.

Some nice spination from what looks to be Coscinasterias
Sea star detail
Uniophora granifera! One of my favorites!
Beaded Seastar

Wednesday, August 10, 2016

HYMENASTER Deep-Sea Slime Stars from the Atlantic and Pacific!

From 2001. Hymenaster pentagonalis from the Hawaiian Islands region. Image by H. Reiswig
Probably one of my FAVORITE deep-sea starfish, other than brisingids has to be these enigmatic and bizarre deep-sea "slime stars"! aka the genus HYMENASTER in the family Pterasteridae!  I've talked about these briefly in a prior account of shallow water slime stars in the genus Pteraster here. 

My first exposure to LIVING Hymenaster was back in 2001 when I was working with Craig Young on an expedition to study glass sponges in the Hawaiian Islands (see pic above)

I got an opportunity to collect a bunch of deep-sea asteroids at that time and saw my FIRST deep-sea slime star!!

and a few minutes after, I discovered for the first time that, just like their shallow-water cousins, Hymenaster could emit mucus just as effectively!!  In other words SLIME!
Image by H. Reiswig.
Hymenaster is a WEIRD animal. The entire surface has evolved into a strange soft covering, This varies in different species. In some the body is membranous and kind of leathery, others, sometimes soft and in others, almost completely gelatinous. In those latter gelatinous species, almost the entire body, save for the tube foot grooves, mouth frame and various other structures are nearly all soft and squishy. Very little in the way of "hard parts"

The name Hymenaster translates from the Greek into "Hymen" and "aster" or "Membrane Star" which as we shall see is pretty fitting.

The body is almost transparent. You can see the five radiating tube foot grooves plus the mouth and some spines and etc. in the surface areas which you can sort of see through.
 Hymenaster sp. from Maro Crater (Hawaiian Islands)
Hymenaster's translucent body draws an analogous comparison with many deep-sea sea cucumbers such as this one observed at 4800 m in the Hawaiian Islands... So perhaps there is an adaptive advantage to having this gelatinous body wall?

Hymenaster occurs all throughout the world: Atlantic, Pacific, Arctic, Indian and Antarctic (i.e. the Southern) Ocean. The genus includes approximately 60 species.

Hymenaster lives primarily in very DEEP water (1000-8400) with some species occurring in the DEEPEST of ocean depths, setting records for starfish deep-sea occurrence (here). The deepest known Hymenaster was recorded from 8,400 meter depths aka the ULTRA abyssal!!  But some, such as the shallow Hymenaster pellucidus take advantage of the cold water in the Arctic and can occur in as shallow as 128 meters.

The problem with many of these deep-sea pictures is that the diagnostic characters used to ID them are from characters that are either on the underside, along the tube foot grooves or actually INSIDE the body. Color, shape and surface texture all seem to it can be difficult to "nail down" which species is which..

Unfortunately, these animals don't hold up well after collection. Here's one after the delicate touch of a robot submersible. Think about what what a delicate animal like this looks like AFTER a trawl net has dragged it for about an hour on the sea bottom!
It depends on the species of course, some of the tougher species are pretty tough. This one looks like its in pretty good shape. Still weird but the features are all there...

One of the most complicated aspects of studying these animals is "matching up" the examined, often damaged specimens from above with the living animals. And lately there have been a LOT of images of living animals!

There is nearly NOTHING known about the biology of these animals. What do they eat? What is the slime used for? What is the gelatin-like body an adaptation for?  Where do the species live? Are they separated by depth? How have they evolved?

ALL of the observations below have screengrabs via the Okeanos Explorer program!!

The deep Pacific is a VAST area. Images below are mostly from North Pacific observations..undoubtedly there remain many MORE species further south.  

A Pink One from the southern region of "Bank 9" in the Hawaiian Islands region

here was an ENORMOUS one from the Hawaiian Okeanos that was HUGE about 20 cm across!

This one nicely illustrates the osculum, which is that big center hole on the surface which is how water enters the cavity surrounding the body surface thus bringing water/gases to the papulae (i.e. the gills) within..
 It gave us a nice show with its opening and closing osculum!

This is what I previously identified for HURL as H. pentagonalis..but it doesn't seem to match the orange one at the top of the post above in terms of color or texture. So, possibly something else.

From East Necker Seamount in the Hawaiian Islands region. A different color from H. pentagonalis.

and yet ANOTHER Hymenaster species (I think??)  from Salmon Bank in the Hawaiian region. White with flyffy surface texture!

A recent image of Hymenaster sp. from McDonnell Guyot in the Wake Island region. Same genus but the surface texture is VERY different..

Here is yet ANOTHER species from Barkley Canyon off British Columbia.. Again, very different body shape, surface texture and color..
Deep-sea Slime Star

Its also entirely POSSIBLE that SOME of these Atlantic species might actually be the SAME ones as the Pacific ones.. There are some similarities below with the ones above..

From Puerto Rico

From Atlantis II Seamount (North Atlantic)

From the Atlantic, Mytilus Seamount (via Okeanos). On top of everything else, the surface membrane is "ballooned" up... which is more mysterious behavior.

From Physalia Seamount (North Atlantic). Honestly, this one might be something else entirely. The surface texture is unusual. 

Big goopy starfish! The mysteries remain!