Deep-Sea Coral Starfish PREDATORS! New Genus! New Species! Deep-sea Corals shudder in FEAR!

So, today you guys get something a little special that I've been cooking up! After a few years of gathering specimens and working up data, I finally published this paper with Martha Nizinski of the National Marine Fisheries Service (NMFS) and Lonny Lundsten of the Monterey Bay Aquarium Research Institute (MBARI).

Basically, my paper describes THREE new species and one new genus in the subfamily Hippasterinae, which is a group within the family Goniasteridae. Goniasterids occur all over the world and and are probably the MOST diverse of all the starfish groups with some 64 genera and close to 260 species!

This one subfamily, the Hippasterinae, includes the familar Hippasteria (below) which live primarily in the deep-sea, but in some parts of the world, can be seen SCUBA diving depending on where you live (e.g., Washington, Oregon, British Columbia, etc.).
Hippasteria has been known to humanity for a LONG time. It was literally one of the first sea stars described by European scientists in 1840. But for the most part, its a deep-sea species and we didn't know much about it or its relatives up until recently.

So, it turns out that Hippasteria's got some pretty important eating habits. It and its relatives are voracious predators of cnidarians, specifically deep-sea CORAL. I've written about various sea star corallivores before (early on in the Echinoblog-here).

But as a quick reminder-Hippasteria (and its relatives) aren't the ONLY asteroids that feed on "corals" (which can be broadly defined as almost any cnidarian with a biogenic skeleton).
Shown above, is Acanthaster planci-the infamous Crown-of-Thorns starfish which attacks and devours primarily shallow-water tropical "hard" coral (i.e., scleractinian). While the above species has grown to plague proportions-it is an important member of the coral-reef ecosystem. As it is likely these deep-sea corallivores are ALSO likely to be... So, how did this whole process begin? As with many things...it started with me identifying a starfish...

Discovering New Deep-Sea Coral Eating Starfish!

My colleague, Dr. Martha Nizinski approached me several years ago with some pretty large-sized starfishes from the tropical Atlantic.

These were in the NMNH collections as part of the considerable "backlog" of unidentified material from her studies with the Johnson Sea Link. I had just arrived and was examining everything that I could...
It turns out that there were not one but TWO species among the specimens that Dr. Nizinski had collected!

One was a rare species called "Hippasteria" caribaea that turned out to be incorrectly classified and was more properly placed in a Pacific-only genus called Gilbertaster, making the full correct name Gilbertaster caribaea.

It turns out that Gilbertaster caribaea is rarely encountered. Only 6 specimens are known
Its a very neat looking animal with all of these very LARGE lip-shaped pedicellariae.

Pedicellariae are pincer or wrench-shaped structures that sea stars use to interact with the environment.

Perhaps they are used to fend off predators? or perhaps to keep their surfaces clear of settling debris? Its not clear what the function is in all taxa... but one thing IS clear? There's a LOT of pedicellariae on the body surface...(each lip-shaped pedicellariae is about 2-5 mm long each)
and there's a bunch of them on the oral surface around the mouth (again, each about 2-5 mm long each)

AND in addition to Gilbertaster caribaea above, there was ANOTHER SPECIES. One that had NOT been recognized by scientists before. Not only was it a new species...but a new GENUS.

The animal has a really stout, heavy body and so I called it Sthenaster from the Greek "sthenos" for strength and -aster for star. So, "Strong Star"
It too has the many, many large pedicellariae...
Finally, I named the species after my colleague Dr. Emma Bullock in the NMNH Mineral Science Department, with the name Sthenaster emmae !!

Dr. Bullock is shown here holding her namesake!
At about the same time, Lonny Lundsten, one of my colleagues from the West coast at the Monterey Bay Aquarium Research Institute had just returned from several cruises off the coast of California..
And he had discovered several NEW specimens of ANOTHER rarely encountered sea star in the genus Evoplosoma. At the time, Evoplosoma was known less than about a dozen specimens worldwide

Here's a pic of the Atlantic species to give you an idea of what they look like...
Lots of spines and pedicellariae...

Well, it turns out that Lonny had MORE than just the preserved specimens..he also had VIDEO and photos of these animals on the sea bottom (>2000 m depths!) doing stuff like this!
NO species of Evoplosoma was known from off the west coast of North America! After examining specimens, it turned out there were TWO distinct species of Evoplosoma present. Both were observed feeding on deep-sea corals.

I named one, Evoplosoma voratus. "Voratus" means to "greedily devour" and the second, Evoplosoma claguei I named for Dr. David Clague an MBARI Geologist who headed the mission and collected several of the specimens!
I proceeded to engage in a phylogenetic analysis of these and other related sea stars in the Hippasterinae/Goniasteridae, including Hippasteria
and the closely related Cryptopeltaster
using computer software to analyze the external characters to group similar taxa together...
To get a tree that looks like this!

The tree shows some interesting stuff... the genus Evoplsoma is found ONLY in the deep-sea and is probably a derived (i.e., highly specialized) member of the Hippasterinae. And so, its ancestors probably hail from a shallow-water ancestor.

I also realized that there were observations of coral predation from nearly EVERY member of the Hippasterinae. There was no evidence for Gilbertaster feeding on coral-but there was for all the rest.

As you can see here, the starfish is actually climbing UP the stalk and leaving the skeleton of the animal devoid of living flesh as it devours the animal like delicious deep-sea cnidarian lollipop!
I checked the gut contents of our new genus and species, Sthenaster emmae which had been collected in close proximity to deep-sea corals! Examining the food left in the stomach of these animals resulted in our discovering ...SCLERITES
Sclerites are skeletal bits from certain kinds of deep-sea corals. They are also distinctive enough for some species that they can be used to identify species!! Later examination of the collection video of these animals did in fact show that these WERE feeding on deep-sea corals!

I've also gotten to looking for these animals on the internet. Its actually seen on quite a few oceanographic expeditions in the Atlantic and the Pacific!

Here is an image from a 2004 Alaskan Seamount expedition. Probably Hippasteria...
Here's another image of what is probably Evoplosoma from the same 2004 Expedition
And from a 2003 HURL mission to Hawaii...Although I'm not sure which species this is..
and I observed Evoplosoma on the 2009 Pacific Northwest Expedition!

And this 2004 account of what turns out to be a new species of Evoplosoma from Bear Seamount in the Atlantic!
Potentially, we are seeing the discovery of a pretty widespread ecological interaction...and an important part of understanding deep-sea corals! A conservation priority in the deep-sea as outlined by NOAA and others...

Hopefully the paper will find good use as discovery of these sea stars becomes increasingly more common...

Iconaster longimanus: got a starfish? Share it on the Echinoblog!!

(Iconaster longimanus by Franca Wermuth)

Welcome to the first post of the new year! I thought I would kick-off the year with a new kind of post!

Many of you know that as a taxonomist, I am happy (when i have the time) to identify images of various species that are sent to me from YOU the public. BUT up until recently, I performed this service privately. I am one of the few people in the world who can ID these beasts with some authority, so my time to do "freebies" is at a premium.

So, I was thinking that pics of animals I identify CAN (and should?) BE SHARED with the PUBLIC!

and so here we are.

Today's beast is member of the Goniasteridae, called Iconaster longimanus. A beautiful animal that is found in the central Indo-Pacific, including the Philippines, Singapore, the South China Seas, Indonesia, SE Arabia, and in Northern and western Australia, including Queensland in 6-85 meter depths. You can find a paper I wrote about the taxonomy of Iconaster here.

Today's picture was provided by marine photographer Franca Wermuth, whose website can be found here. My understanding is that she's normally a nudibranch afficionado, but has now added starfish to her list of interests! The animal above was photographed in the Philippines from Romblon (Romblon Province, Romblon Island), next to Lugbung Island in about 35 meters depth. Water temperature was 27.2°.

Relatively little is known about Iconaster's biology. Its name Icon is from the Greek eikon for portrait or image, and possibly refers to the way the marginal plates form a frame around the edge. And -aster of course refers to the word "star".

Its species name longimanus translates into "long hands" which clearly makes reference to the extended arms.

The Pulau Hantu blog has a nice picture and an interesting write up on its conservation in Singapore
A quote from their blog

What may seem common to divers around the the reefs of Pulau Hantu and the Southern Islands, is actually an animal that is listed as "Vulnerable and rare" by The World Conservation Union's Red Data Book.

The icon star (Iconaster longimanus) is a striking species that occurs on lower reef slopes and the adjacent sea bed around many of the Southern Islands. It feeds on epilithic growth on hard substrata and coral rubble. Zoologically, it is interesting as it has large lecithotrophic eggs which show abbreviated development, without a larval stage. In recent years this sea-star has been found to be moderately common on and around many of the reefs fringing the Southern Islands. However it is considered vulnerable because living on and near the slopes of fringing reefs, it is threatened by reclaimation activities. Additionally, its attractive appearance many lead to over collection as a curio. Such threats are of particular concern given its slow growth rates.

The only thing I can add? Iconaster has been made into a plastic toy!
Happy 2010 Everyone!

A tease....

This is something that I'm working on...but I can't tell you what it is!.....yet! I just thought the image was interesting enough to post as-is!

Enjoy!

Tosia Times TWO! Discovering NEW CRYPTIC species of Australian Biscuit Stars!

(Image courtesy of Kate M. Naughton!)

Today, some neat science with a cool Australian starfish!

Today's blog comes from my colleagues Kate Naughton and Tim O'Hara at the Museum Victoria in Melbourne, Australia! who have JUST published a spankingly fresh paper describing a NEW species of the familiar Australian biscuit starfish, Tosia!

(one is Kate and one is Tim-can you guess which one?)

I have mentioned Tosia before on the blog...It is a starfish in the family Goniasteridae and its genus name is the Latin word for "Inestimable" which alludes, of course, to the animals' incredible natural beauty!

Tosia, as I define it, is found ONLY in Australia, where it is quite abundant and relatively well-known to the people who study marine biology thereabouts. One species in particular, Tosia australis, occurs widely throughout the temperate southern part of Australia.

(Image courtesy of Kate M. Naughton!)

Taxonomists have been noticing T. australis for YEARS and describing a myriad of species. Over the years, some FOURTEEN species have been described-but refinement of species concepts (and removal of unecessarily redundant species) have whittled down the total number to three.

It has led to the identification of what's called the Tosia australis species complex!! That's what happens when you have a lot of closely-related populations that all may or may not be different species.

These populations usually show tenuous morphological differences between different "species" in the related network which are typically spread out over a relatively large geographic region. The North Pacific 6-rayed starfish Leptasterias, which I've written about here, is also a species complex.

Something NEW! Brooding Discovered!
So, for an animal that occurs so close to shore, surprisingly little was known about it. In the 90s it was discovered that Tosia australis was a SPECIAL kind of starfish!! It showed an unusual reproductive behavior: BROODING juveniles! That is to say, its offspring live on the adults.
Not too unusual in vertebrates, but VERY unusual in starfish!

Also, Tosia australis has been known since 1840-so it took over 150 years for them to discover that it brooded juveniles!! So, this led to some close observation.

(Image courtesy of Kate M. Naughton!)

So, the investigative talents of Ms. Naughton and Dr. O'Hara were applied towards the question!

Did the difference in larvae mode also translate into further biological differences??

During a museum visit to Melbourne, I was talking shop with Kate and Tim. I was pretty sure that all the morphological variation in the species complex would translate into regional or environmental differentiation VS. Tim who believed that they would split out by larval type.

Larvae in several other species is highly variable but often did not translate into phylogenetic differences..so I figured it would probably do the same here.

And in fact, I was SO confident I was right, that I wagered a gentlemen's bet with Dr. O'Hara that I would be right!

So-I said: "Go get the DNA and prove me wrong!"

And so they did (and had started before I had made the bet!)

Oops! Guess I just lost 10 bucks!
The final analysis following a survey of many specimens from Victoria, Tasmania, and South Australia supported three different species, including something NEW that hadn't been observed before!!!

(Phylogenetic Tree inferred from COI and 16S RNA-and redrawn here by the Echinoblog Art Department!)

Several specimens from Tasmania and Victoria were supported on a separate clade as a NEW SPECIES. Kate came to call it Tosia neossia. The species epithet neossia is Greek for "nest" in reference to this species' brooding habit.

And here it is!

(Image courtesy of Kate M. Naughton!)

T. neossia is very similar to the well-known T. australis but, aside from a bunch of external morphological features, one important feature sets them apart....

The difference is in the Larvae (i.e., juvenile starfish)!

One of the fundamental differences here is that of the difference in larvae between Tosia australis and T. neossia!

The new species Tosia neossia had BOTTOM larvae with large yolky eggs (this kind of egg is called lecithotrophic)!!

(Image courtesy of Kate M. Naughton!)

Unlike more "typical" larvae, these tiny guys were negatively buoyant (that is to say, they sink rather then float)!

They are emitted from the mother and crawl along the bottom using little lobes to get around until they fully develop into larval adults. These little BOTTOM larvae (shown here as early stage larvae) can be seen here (courtesy of Kate Naughton!)

(Image courtesy of Kate M. Naughton!)

Here is where the larvae begin to change into what Kate calls the "tripod phase". These utilize a large lobe that helps move the larvae around before it begins to attach someplace on the ground after developing to the right stage....

(Image courtesy of Kate M. Naughton!)

....And finally, here is the settled larvae (oral view-looking up into the mouth). Note the tiny red dots, which will eventually become the eyespots!

This little fellow will develop into what will eventually become

(Image courtesy of Kate M. Naughton!)

....the adult!

This is in direct CONTRAST to Tosia australis which has SWIMMING juveniles that emerge from the aboral surface (via gonopores on the top surface).
In contrast to the larval juveniles of T. neossia, T. australis has eggs that are postively buoyant and are covered with small CILIA!! That is, they have little beating hair-like threads that can keep them swimming before they settle out somewhere.

Summary Time!

In addition to the DNA and morphological evidence (you can go to the paper for details) the larval story goes like this:

Tosia neossia! Gonopores open on ORAL surface (i.e., DOWN) where the juveniles sink to the bottom. They are bottom-living and non-ciliated until they grow into juvenile adults!

Tosia australis! Gonopores open on ABORAL surface (i.e., UP) where the juveniles float and can sustain a swimming stage until they settle to the bottom and grow into juvenile adults

TWO species. VERY similar looking! but with DISTINCT juveniles growing into adults that are hiding right in plain sight!

Best 10 bucks I ever lost.

Thanks to Kate Naughton for helping me with images!