Monday, November 30, 2009


First...Go HERE and see this AWESOME video of Antarctic Starfish [Odontaster validus (99% of the ones in the pic) and some Lysasterias (the big white one) thrown in for good measure] feeding on the dead carcass of a dead seal pup!! Ha! take that mammals! And there's some big Antarctic nemertine worms (probably Parborlasia corrugatus) thrown in for good measure!!

What??? You want MORE time lapse???! Here's some Canadian Atlantic species thrown in for good measure! Looks like primarily Leptasterias polaris (big 6 rayed beast) and Solaster endeca (8-12 armed one with stripes)And to the music of Benny Hill no less!

And yet, EVEN MORE Time Lapse video?? here ya'go! A tiny aquarium asterinid extending its stomach out onto the glass to feed!

Finally, here's some Patiria miniata gliding over the bottom of the Pacific!

Tuesday, November 24, 2009







Monday, November 23, 2009

Echinoblog Holiday Life Lesson # 34

Do NOT mix up your holiday shortbread with cookie-shaped starfish!! (Ceramaster granularis)
(no actual starfish specimens were harmed in the production of this blog)

Tuesday, November 17, 2009

The Pisaster Post! Posterchild or Portent ??

This week, we're talking about the Pacific Northwest Intertidal!!

And what animal is more iconic to this area then Pisaster ochraceus (family Asteriidae)-the familiar intertidal Ochre Star found on rocky, mussel-laden substrates on from Alaska to California to Mexico. Some more basic information is here.Interest on this species has shifted over the years and seems to change based on some of the "big science" of the day. Yet another sign of how the humble starfish has incorporated itself into the fabric of the BIG scientific picture!

So, today some highlights of the importance of the ever-humble intertidal Pisaster ochraceus and how its study has varied over the years....

1. The Keystone Species Concept-Ecology's Posterchild. Probably one of the most lasting ideas from the 1960s and 1970s was the hypothesis developed by ecologist Robert T. Paine who identified Pisaster ochraceus as a keystone species (keystone shown below in grey).To quote Wikipedia:
A keystone species is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass
This keystone is a crucial block in an arch that keeps it from collapsing. This is analogous for Pisaster's influence on the mussels and the other invertebrates that exist in a rocky intertidal ecosystem.
The loss of the "keystone species" results in a drastic shift among these species....The idea has endured and while not embraced by everyone- remains a mainstay in basic ecology books. More details on this notion can be found here.

along with its prey, the mussel Mytilus are almost ALWAYS the featured example... the POSTER child for the keysone concept-and for this reason, is probably even better known then the Atlantic Asterias!
This was (and continues to be) an important ecological notion during a time when the ecosystem and ecologists were in ascendance and ecology was a huge primary mainstay of biological research!

2. Pisaster as a Portent of Change?? The Canary in the Cage of Climate Change??
Probably one of the biggest, new research directions these days?

Understanding Climate Change and in turn...increased ocean temperature, which has a HUGE impact!

It affects ocean water chemistry. Water chemistry in turn can change everything from mineral absorption, feeding behavior, physiological systems to larval settlement. These in turn can have influence on MILLIONS of tiny larvae in the water. As well as the MANY adults those starfish grow into.

This translates into many people interested in the effects of increased temperature and heat relative to the ability of common species to adjust. Will Pisaster ochraceus take on a new status as a possible indicator species (i.e., canary in a coal mine) for climate change effects in marine systems?

Here is a survey of three recent studies (2008-2009) that have looked at how Pisaster holds up!

Elevated water temperature and carbon dioxide concentration increase P. ochraceus growth!

(Diagrammatic graph by Echinoblog Art Department!)

Rebecca Gooding, Christopher Harley and Emily Tang at the University of British Columbia published this study in the Proceedings of the National Academy of Sciences wherein they found that increases in temperature from 5 to 21 degrees C led to increases in feeding AND overall growth.

This bucked the predictions that the decreased carbon dioxide resulting from increased temperature would prevent animals that use calcium carbonate to form their skeletons (such as coral)!!

Solar radiation plays a role in P. ochraceus habitat selection
(Diagrammatic graph by Echinoblog Art Department!)
A 2008 paper by Jennifer Burnaford and Melissa Vasquez at the University of Puget Sound studied where P. ochraceus occupied habitat and their tolerance of Ultraviolet radiation.
The short version of this-the authors found that in artificial lab experimetns, P. ochraceus avoided ultraviolet and "photosynethetically active radiation" and observations of Pisaster in the intertidal found that 85% of them occurred in shaded habitat underwater where they were shown to preferentially avoid direct exposure to sunlight (see diagrammatic graph above!).

P. ochraceus avoids extreme body temperature by pumping its body full with cold sea water!!

(Diagrammatic graph by Echinoblog Art Department!)

Sylvain Pincebourde, Eric Sanford, and Brian Helmuth recently published this paper (2009). A popular account can be found here (and for shame to Live Science for misspelling "ocher").

Their paper details how Pisaster ochraceus was observed to increase the amount of colder water in their body cavity lowering their body temperature during the subsequent low tide in response to the temperature.

Sense it getting warm? don't like it? Just PUMP IT UP! with cold water! (see diagram above)

But climate change has a huge potential impact on animals that do quote in their words:
When placed in a global change context, these results suggest that a continued increase in ocean temperature may compromise the ability of sea stars to avoid thermal stress during aerial exposure at low tide.
Has the humble Pisaster ochraceus gone from ecological poster child to a possible portent of climate change to come??? Time will tell....

Monday, November 16, 2009

Meet...The Farallons: ROCKY Intertidal Wilderness of San Francisco!!!!

So, one of my esteemed colleagues at the California Academy of Sciences-Dr. Rebecca Johnson Rodgers, who has worked with the Echinoblog while teaching at San Francisco State,is currently out on the Farallon Islands with the Rocky Shore Partnership monitoring various intertidal invertebrate critters. So, I wanted to give them some bloggy love:
Click here for their blog...
For those who are not familiar, the Farallon Islands are some remote islands, about 27 miles outside the Golden Gate Bridge (outside of San Francisco Bay).. Here is the Wikipedia page for the Farallons for more..

But the short version is, that they are remote islands that are protected as a wildlife refuge. The Farallons are great for birdwatching and have lots of great (hopefully still...) pristine intertidal reef habitat.

Plus, as a bunch of rocky islands out on the outskirts of San Francisco Bay, you get lots of this...

Along with many of the classic California invertebrate fauna..

Leptasterias "hexactis", shown here with brooding eggs!! This is part of the Leptasterias species complex which I have written about here and here
and, of course, the good ol' workhorse starfish Pisaster ochraceus, which I will be writing up in the blog later THIS WEEK!!!

and just because they're so dang beautiful...these mollusks too!!! This used to be called Tonicella lineata, but I think the name's been changed recently...
....and back in the Paleozoic when I took Intertidal Ecology, this thing was called Calliostoma, but I gots no idea what the kids are calling it these days!
GO check out the Rocky Shore Partnership BLOG and I'll be back in a few days with some PISASTEROUS starfishy goodness for all o' y'all!

Monday, November 9, 2009

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 paper describing a NEW species of the familiar Australian biscuit starfish, Tosia in Invertebrate Systematics!
(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 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!

Wednesday, November 4, 2009

Bioluminescence 2009 Expedition! Swimming Cuke Video & MORE!

Echinoderm Image & Video Highlights from the 2009 Bioluminescence Expedition! (from deep-sea Bahamas)

Video of the deep-sea SWIMMING holothurian Hansenothuria benti
Miller & Pawson (graciously identified by Dave Pawson, Curator of Echinoderms at the NMNH!) shown here being captured by the Johnson Sea Link submersible!

Endoxocrinus maclearanus flank a purple sea fan with a snake star.
(Image from the Bioluminescence 2009 Expedition, NOAA/OER website)

The Deep-Sea brisingid starfish, Novodinia. Probably Novodinia antillensis...


Dr. Charles "THE MAN" Messing. Crinoid expert, snappy dresser, thespian, and dude!! He discovered a new species while on this cruise ...

The TRUE (?) meaning of Aristotle's Lantern??

This week: fun ancient etymological mysteries!! Forget the true meaning of Christmas, What is the true meaning of Aristotle's Lantern???

Based on a recent paper (Cahiers de Biologie Marine 49: 299-302) by Eleni Voultsiadou and Chariton Chintiroglou at Aristotle University in Thessaloniki, Greece we have a new perspective on the roots of the special jaw apparatus found in sea urchins (see below).

A nice review of sea urchins and Aristotle's Lantern is found at Daily Kos.
So. All up to speed? Aristotle's Lantern. check. Sea Urchin jaw. check. Great!

What's next?
The "backstory" about this structure, of course, invokes the famous Greek scientist/ philosopher Aristotle who at some point apparently described this structure as a "lantern".
At face value this seems reasonable enough and enough historians have seemingly verified the story over the years.... (or have they?)
But what if Aristotle did NOT, in fact, mean that the JAW was the "lantern"????

WHAT IF Aristotle's Lantern ACTUALLY referred to the WHOLE BODY (i.e., the test)?? And what we've been taught all along was actually wrong (or mistaken)??

Apparently there had been some historical ambiguities with the original translation.  From Aristotle's original History of Animals as such (boldface is mine):
In respect of its beginning and end the mouth (or body) of the urchin is continuous, though in respect of its superficial appearance it is not continuous, but similar to a lantern not having a surrounding skin.
This little section is apparently problematic for several reasons:
  • it is unclear whether the text refers to stoma, i.e. jaw apparatus or soma, i.e., body (hence drawing attention to the mouth vs. body)
  • the phrase "surrounding skin" and mention of continuity.
Although several scholars have since embarked upon a historical study of the etymological roots of Aristotle's Lantern (most of whom seemed to be happy with the "lantern" as the translation), no actual archeological evidence had actually been brought to bear on the question.
(An ancient "lamp" p.s. to paleontology students? this is where the phrase "lamp shell" for brachiopod comes from!)
The scholarship of Voultsiadou & Chintiroglou have discovered that ancient Greek lamps (circa 5th to 9th c. BC) (i.e., the light source, usually candle or oil lamp) were placed inside lanterns, which were usually translucent skins or perforated ceramic or bronze, to protect the light source from the wind. Thus preventing them from blowing out.

Thus, an ACTUAL lantern from Aristotle's time, looks like this (remember the lamp or light source goes inside):
(A Vergina lantern from the tomb of King Philip II, dated to the 4th Century BC in Northern Greece)

Now, compare and contrast with the MODERN version of a lantern!
(with a "lamp" inside)

(I wish I was kidding about this-but isn't it awesome?)

They proceed to outline how all of the additional incongruities of the original passage can explained based on the assumption that Aristotle was comparing the sea urchin test with a bronze lantern, distinguishing it from those ancient lanterns which were made of skin or other soft material.

Thus, they propose that the "test of the sea urchin and NOT the jaw apparatus should be called 'Aristotle's Lantern'."

Monday, November 2, 2009

The Basics: How to Tell Sea Stars (Asteroids) from Brittle Stars (Ophiuroids)

So, for various reasons, I thought I would do something a little unusual today and actually delver into some basic "how do you tell the difference between x and y" type stuff today. Why? Especially when you can find these sorts of characteristics listed in any Invertebrate Zoology text book?

A confluence of things:

1. Its November. And all over the country, bunches of Invertebrate Zoology students are probably hitting the "Echinodermata" part of their class by now. Let's make it easier for them!

2. Certain high-traffic informational websites, which shall remain nameless, seem to have MIXED UP the difference between asteroids (starfish, sea stars) and ophiuroids (serpent stars, brittle stars, basket stars). And SO, I feel its about the right time to make this information more WIDELY available...

3. I've never done it before!

So, here's some basics!

To start off, BOTH asteroids and ophiuroids are members of the phylum ECHINODERMATA. To show the parallel, humans are members of the phylum CHORDATA. Surprisingly though Chordates and echinoderms are both more closely related to one another then they are to say, insects, mollusks, or crustaceans.

First, Starfish!!

Starfish belong to the Class ASTEROIDEA . When you look at the roots words "Aster" means STAR and "oid" literally means "resembling" or "like"..So scientific term translates to "Star-like".
In the truest sense, the 'common name" is ASTEROIDS.

But of course, these are also referred to by a variety of names, so that they are not confused with asteroids in space!:

sea star. starfish. In Spanish: estrella de mar. In French: etoile de mer. In Japan, they are called hitode which alludes to the name for "hand" or "palm".at about Ophiuroi?
The given name for ophiuroids is a little more indirect. The class name "Ophiuroidea" refers to "Ophios" which refers to the arms as snake or serpent and "oidea" which means "resemble" or "like"...probably in reference to the arm shape and/or behavior of the animal when alive.

The resemblance to asteroids was noticed early on, of course. And several early designations of these animals actually refer to them as "Asterias" which is the name later tied specifically to asteroids.

So, How do you Tell them APART???

Some easy diagnostic characteristics!

1. The Madreporite or Sieve Plate. You know that offset "hole" that you see on starfish like this one?

This plate is thought to serve as (at least) one place where water enters the internal body cavity of the animal. ALL echinoderms have a madreporite-but its location and shape is modified to one degree or another.

In asteroids the madreporite (also called a sieve plate) is located on the top or aboral surface as indicated by the red circle.
BUT in ophiuroids (brittle stars and such) the madreporite is located on the BOTTOM or ORAL surface. As seen here:
2. Tube Foot Groove in Asteroids (starfish, sea stars) is OPEN. Although the degree that this groove is open varies, it should always be open to the outside. The tube feet emerge from this open groove and lead into the mouth.
In contrast, such a groove is ABSENT in ophiuroids (brittle stars). The oral surface of the arms is covered over with a "ventral" plate. The tube feet can emerge through small openings but they are NOT open to the outside in the way that asteroids are....

3. The Fundamental Structure of the arm is DIFFERENT.
In asteroids-there are internal ossicles, which act as sort of support struts. The TUBE FEET emerge through these struts and emerge into the tube foot groove.

Here is a cut away showing these internal ossicles called AMBULACRALS which run down the radius of each arm. These ossicles join and form a sort of rafter-like formation that sit OVER the open tube foot groove (above). So, the tube feet drop down through the ambulacrals and emerge in the tube foot groove.
Ophiuroids actually DO have these structures, but they are modified quite differently into solid forms that resemble vertebrae (i.e., the bones in our spine).

In ophiuroids, these vertebrate are tightly enclosed by additional plates that tightly cover over the surface of the arm, including the bottom (see above). Tube feet emerge on the bottom, but only through special pores and NOT through the corresponding ambulacral ossicles.

4. The Mouth and associated skeletal parts is different. At this point, I can start to get into a whole bunch of complicated skeletal jargon associated with the skeleton that forms the mouth frame in a starfish (aka an asteroid-seen here looking down through a mouth)....
versus the one that forms the mouth of an ophiuroid... (seen here looking at the oral surface up into the mouth). Basically, there's a WHOLE BUNCH of changes in the skeletal architecture surrounding the mouth, as its directed towards a substantially different way of life...

(note that brittle stars don't drop an eversible stomach out of their mouth!)5. The Overall Body structure is different. The arms and disk of a starfish tend to be confluent with one another....Plus, the body cavity between the arm and disk is pretty open.
In brittle stars, the arms and disk are sharply set off from one another. The disk is a distinctly separated structure from the rest of the arms.

Asteroids and Ophiuroids are DIFFERENT but closely related.

There are literally, whole books, papers, and multi-year studies written on the subject of which characteristics are used to define the definition of "asteroid" versus "ophiuroid" (often in relation to older fossil forms) and it's important not to call one the other!! (even with common names).
In the truest sense, Ophiuroids are not " sea stars" or "starfish".