New Species of Sea Stars from the North Pacific and BEYOND!

This week I announce a NEW paper in the latest issue of the journal ZOOTAXA describing a new genus and THREE new species of deep-sea starfishes! Vol. 4175 (2): 101-141 

You may recall back in 2009 when I accompanied the Monterey Bay Aquarium Research Institute (MBARI) on a 10 day cruise exploring the North Pacific on the Juan de Fuca and Gorda Mid Ocean Ridges off the Oregon coast. Here was the cruise website.  I blogged about it here.

When we returned from the expedition I was VERY excited because we had collected MANY specimens and several were either new records of rarely seen species or outright NEW species!

I would like to give a big shout out to MBARI because almost EVERY thing they send me turns out to be a NEW species!  Here's a new coral-devouring star I named after MBARI geologist Dave Clague  and here was a poraniid starfish that was observed climbing up a black coral (antipatharian) to devour it

One of my favorite undiscovered starfish was this one, Paulasterias macclaini which I had to describe a whole FAMILY and genus in order to accommodate it!  This species was named for Dr. Craig Macclain, at Deep-Sea News, who had invited me on the cruise.

I wrote about it here.  But he was VERY happy to write up something about it on Deep-Sea News! (here)  

Well, describing that 6 rayed star took quite a bit of effort but there were many, MANY more species to understand!!!

We also collected many of the more 'non-descript' stars that we encountered as well as several others which turned out to be UNDESCRIBED species!! 

And YES its literally taken me almost 6 YEARS to get all of this done. As I've discussed before (here), it can sometimes take quite awhile for a species to be formally described.

 One report made the case it takes an average of 21 YEARS for a specimen to go from collection to publication! (I've summarized it here)

The starfish I reported on in my Zootaxa paper are members of the Goniasteridae, the most diverse family of sea stars, which includes over 260 species in 65 genera!  Most goniasterids live in relatively deep-water (continental shelf and deeper) but historically, there haven't been many of them known from abyssal and lower bathyal (i.e., >1000 meter) depths.

Only recently have we been seeing better collections of these animals from these depths. As I've reported below, some were collected from below 4000 meters!

Sibogaster nieseni! 
The first few specimens of this species were collected by the Monterey Bay Aquarium Research Institute from Taney Seamount (off the coast of San Francisco) from abyssal depths (over 3000 meters!).

It is named for one of my former advisors from San Francisco State University: Professor Tom Niesen (now emeritus)! Author of the Marine Biology Coloring book and noted intertidal naturalist/ecologist along the California coast! 

He gave me my first shot at grad school and happily, his advice and instincts correctly guided me through my early years as a Masters degree student!

photo by J. Sharei

It seemed VERY appropriate to name this species, from off central California, after someone who has done so much to educate others about the significance of the invertebrates of the coast!! 

Interestingly, as I was in the process of writing it up, I suddenly became aware of multiple specimens of similar individuals from OTHER oceans in museums where I was NOT expecting to see them!

This one for example, turned out to be almost identical to the Pacific one I was working on but was from the tropical ATLANTIC! and even one from the deeps of Indonesia... 

Also, unusual is how, such a moderately big animal (about 4 to 5 inches in diameter) could have gone undescribed for so long?  But given how deep it was found (2100 to 4175 meters !) its been well "hidden"! 

This species is likely the deepest member of the Goniasteridae known.

and like several other abyssal species, such as the deep-sea sea cucumber Psychropotes, occurs widely, sometimes in multiple oceans

Ceramaster pointsurae! 

This was a tiny little species that I think we collected as part of something else.. perhaps sampling sediment or some other part of the physical environment.

BUT it turns out that it is likely a new and distinct species with some resemblance to the shallow-water species of Ceramaster (aka the cookie stars) in shallow waters..

This species was found during my 2009 trip on the President Jackson Seamont at about 1975 meters! 

This species is named for the Moss Landing Marine Laboratories retired vessel, the Point Sur which was finally retired in 2014. 

I spent many a day sorting deep-sea invertebrates on the deck of the Point Sur and I was saddened to hear about its retirement.

Bathyceramaster careyi! New genus and NEW species! 

Figuring this one out required a bit of detective work, as it turns out...

Several years ago when I was working as a technician for the California Academy of Sciences, I had the pleasure of studying a newly deposited collection of deep-sea starfishes from Oregon State University.

It turned out, that one of the species in the collection was a rarely known species called "Mediaster elegans" collected by oceanographer Drew Carey. To the best of the knowledge of the workers at the time, it was thought that this was a new occurrence, since the original specimens were only known from South America (collected in 1905). 

But as it turns out, after comparing Carey's specimens with the newly collected material by MBARI AND the original type series (i.e., the specimens on which the species was based) it turned out there were actually TWO species present, "Mediaster elegans" (original name) AND this one!  And the one seen by Carey in 1972 was actually undescribed! So, what I'd argue was actually "Mediaster elegans" turns has not actually been seen until now...

and not only that, it had to be placed into a new GENUS in order to be correctly described! 

Boom! NEW genus described! New SPECIES described!

This species was ultimately found to occur throughout the North Pacific between 1700 and 3363 meter depths! 

With this one, named for Dr. Andrew Carey, formerly of Oregon State University! 

The gut contents described by Carey's paper in 1972 suggests that this species feeds on deep-sea sponges.

The paper outlines several goniasterids from the North Pacific at depths below 1000 meters, including several which have not been seen since their description. 

Now that the new genus Bathyceramaster has been described, I can also follow up with a note I made on one of the recent Okeanos dives to Wake Island! 

This white goniasterid we saw at about 2000 m MIGHT be Bathyceramaster, but I'd need to more closely examine the surface to be sure. But if the closeups of the surface texture were correct.. I think maybe??

New discoveries that lead to new questions!! 

What are they eating down there? How do they get so big? Why do some of these species always seem to be alone when you see them? 

My thanks to the Monterey Bay Aquarium Research Institute, the California Academy of Sciences'  Department of Invertebrate Zoology and the Museum national d'Historie naturelle in Paris! 

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

via the NOAA photo library http://www.photolib.noaa.gov/htmls/expl6751.htm

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!)

From MBARI https://twitter.com/sarahkeartes/status/593979334056022016

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?

A NEW paper by Chrysoula Gubili at the University of South Hampton and other coauthors from Southampton, including Elizabeth Ross and Paul Tyler in Deep-Sea Research II  was just published a few months ago exploring the population geography of this globally occurring deep-sea 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) perspective..so, 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!! )

http://archives.starbulletin.com/2007/06/24/news/story02.html

What further mysteries does Psychropotes have in store? I anxiously await the next paper! 

....now 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...

I had amazing office mates! Psychropotes longicauda cake and Deima validum meringues! @echinoblog pic.twitter.com/FHqExLTZ

— Libby Ross (@Libby_Ross) January 27, 2013

And of course Psychropotes stuffed animals.. from Japan of course!! 

from ebay http://www.ebay.com/itm/Psychropotes-varipes-Stuffed-Toy-sea-cucumber-peluches-Kuscheltiere-Japan-Eboshi-/271795943477

Bacteria in the Belly of the Beast! Prokaryote Diversity in Abyssal Sea Cucumbers!

(photo from the USNM Invertebrate Zoology Collection)

This week a follow up to an earlier blog I wrote in October last year about microbes in the guts of deep-sea holothurians!

This new paper is by Teresa Amaro, University of Aveiro in Portugal and her colleagues and has been recently published in Deep-Sea Research I vol. 63: 82-90. (she also wrote the earlier paper that I wrote about above)

This paper focuses on this lovely echinoderm champion-the sea cucumber Molpadia musculus-which occurs throughout the North Atlantic, buried in deep-sea (circa 2000-5000 m depths) mud.

(photo from the USNM Invertebrate Zoology Collection)

Molpadia are infaunal deposit feeders-that is they live buried in the mud, head down with mouth directed into the soft, muddy goo... (the mouth is shown below-this is the part that faces into the mud! Lovely, yah?

(photo from the USNM Invertebrate Zoology Collection)

Their "tails" presumably face upward to permit the feces to vent out on the surface, following ingestion of the mud/sediment...

(photo from the USNM Invertebrate Zoology Collection)

Molpadia can occur in very high biomass and in great abundance on the deep-sea floor with some 220 individuals per square meter!!

Bacteria and Archaea on the Deep Benthic Floor!
So, you've got a big, living dirt-eating vacuum cleaner buried in the mud of the deep-sea floor. What are they doing down there?? What are they interacting with? Are they Eating?

(photo from the USNM Invertebrate Zoology Collection)

For years, it had been noticed that there is actually quite a lot of microbial life present in the oceans. Scientists have been using methods known as DNA fingerprinting to recognize the amount of life that is present on deep-sea bottoms.

The diversity we focus on here, emphasizes two of the major Kingdoms in the overall Tree of Life-The Archaea and the "Bacteria" or the Prokaryotes-those with less developed cells relative to the eurkaryotes. Note in the diagram below.. "Eurkaryota" refers to organisms with full and complete cells, such as algae, protists and all the animals.

(Image from Wikipedia)

The prior blog that I wrote about this showed that there different "kinds" of microbial life present not only on the sea bottom but actually IN the guts of these deep-sea sea cucumbers.

Amaro's newer paper now shows that there is an astonishing diversity of microbes associated with the gut contents in Molpadia musculus! And details the distribution and diversity of the kinds of microbes present.

Amaro and her colleagues surveyed the abundance of different prokaryotes both in the sediment (measured from sediment cores) and at different points along the gut of Molpadia and found this....

(Fig. 2 from Amaro et al., 2012)

First (top-Fig. 2a) , that the actual amount of prokaryotes (this includes both bacteria and archaea) was highest in the top 1 cm of sediment.

Second (bottom-2b) That after survey the abundance along the animal from the gut to the end, the greatest amount of prokaryotes was actually found in the oesophagus (i.e., the front end of the intestine) of the animal.

The latter result likely shows the result of digestion with most of the food (i.e. bacteria) being digested as it proceeds to the midgut and so on...

Both of these results make sense. Prokaryotes are settled out on the surface and the oesophagus (the front end of the intestine) is where all of that enters into digestion.

What kinds of bacterial diversity did they find?
The authors counted the diversity of bacteria in terms of Operational Taxonomic Units (OTU)s-that is a general term that refers to the different types of organisms or species present.

They found 28 to 71 OTUs in the surrounding sediments but about 33 to 105 in the sea cucumber itself!

(Fig. 4 from Amaro et al, 2012)

The authors further compared the abundance and composition of the bacterial OTUs (i.e., the diversity) between the sea cucumber and the surrounding sediment.

Now, if the surrounding bacterial were food-one would expect the same diversity in the sea cucumber as in the nearby sediment.

BUT, as it turns out, about 40% of the bacterial OTUs were uniquely associated with the gut contents and were ABSENT from the surrounding sediments!

Some Further Dynamics from the paper...

1. Prokaryotes decrease in abundance along the gut. From the above Figure 2 we see the abrupt decrease of abundance of prokaryotes from the oesophagus to the hind parts. This was a 6-fold reduction from the oesophagus to the hind gut.

This suggests that GREATER than 80% of the total were digested by the animals.

2. Archaea vs. Bacteria in the Hindgut. They also found that among the prokaryotes-bacteria accounted for only about 55% of the total number found in the oesophagus but only 35% in the hindgut, BUT archaeans actually increased in the hindgut! Why? The authors suggest that the different kinds of prokaryotes are used differently across the intestine..

3. But do the prokaryotes keep Molpadia fed? Well, in a word: No.

It turns out that these bugs only contribute about 0.5% of the total organic carbon used by individuals in the study. The authors conclude that Molpadia, at least, does not rely in any significant way, on prokaryotes for their food requirements.

4. So, if not food-then what are they for?? As indicated above- the DNA fingerprinting identified the fact that the "bugs" in the surrounding sediment were significantly different from those in the sea cucumber itself.

So the authors conclude that the animal carries the prokaryotes around in its gut as commensals-possibly to facilitate digestion in a manner similar to how termites and some mammals (such as ourselves) carry around a prokaryote fauna to facilitate digestion. (think of it as yogurt for sea cucumbers!)

And so there we have it. Some deep-sea sea cucumbers are just big bags filled with prokaryotes that feed on mud and ooze!