Tuesday, June 4, 2013

FIRE Urchins! Brilliant Shallow water cousins of the "tam o shanter"/pancake urchins!

Fire Urchin
Image by Aboireoujtulchien
Last week I reviewed deep-sea echinothurioid urchins aka the "tam o shanter urchin" aka the "pancake" urchin, etc., etc.  I spoke of these more generally in an earlier post. But for some reason I've not had a chance to really showcase their shallow water relatives!
Shallow water echinothurioid urchins are "proper" fire urchins. As opposed to these other "fire colored" spiny urchins, such as Astropyga which are diadematoid urchins. A completely different group!!

"Spiny" urchins are distinguished by the presence of an Anal Cone. See that white bulb on top? THAT is where the poop comes out!  You don't see that in "proper" fire urchins as we'll be seeing.. Note also that the spines are much longer.
Astropyga radiata
(image by Ben Naden)
I've discussed Astropyga on the blog before (here)...

These urchins all belong to the genus Asthenosoma which includes six species spread throughout the Indo-Pacific region.  Here's a neat video that gives you an idea of what they look like..

Yes, the colors are a huge shift in appearance, but similar to their deep-sea cousins, Asthenosoma also has the distinctive "walking" spines...

On this image of Asthenosoma varium the walking spines form a fringe around the lower oral side composed of distinctly yellow spines. My understanding is that most of these prefer soft, muddy bottoms.
Asthenosoma varium
Image by Ben Naden
Some video!
Compare to the walking spines on this deep-sea echinothurioid.
Spiny sea urchin
Image by NEPTUNE Canada
From there we start to see more differences as the spines seem to be bunched up in bundles...
But they remain venomous...
fire sea urchin
Image by JianXu
Some workers have hypothesized that the poisonous spines in deep-water echinothuroids function as hypodermic needles (here by Roland Emson & Craig Young)

And if its not clear by now, YES. They're pretty damn venomous. My understanding is that its very painful.. but typically not lethal.

and they certainly do seem like they do, don't they??
fire urchin IMG_6889
Image by Bruce Magun
Fire urchin's spines
Image by Daniel Stassen

Close ups! showing some of the brillaint colors, spine patterns and etc.. I suspect most of these are Asthenosoma varium
Fire urchin!
Image by MerMate
Image by Daphna130
Fire urchin
Image by lupopeye
Magnificant Fire Urchin
Image by maractwin
fire urchin
Image by Nick Hobgood
fire urchin
Image by B. Maither
Fire Urchin Close-Up
Image by Russell Taylor
Here's some differing species from around the Indo-Pacific

From the Red Sea, Asthenosoma marisrubi with a more mellow look...
Foto-2008-05-08 21.31.25
Image by Key of Life
Here are the spines..still basically the same but different color and slightly different shape..
Asthenosoma marisrubri
Image by Le Congre
Asthenosoma spp. showing many different colors...
Coleman Shrimp and fire urchin
Image by S1mon Mar5h
Image by Clark Chang
IBAb-292 Fire urchin, Asthenosoma varium
Image by Jesse Claggett
Fire urchin
Image by Richard Barnett
What's even MORE interesting? These urchins have tiny critters which live as commensals(?) among the highly poisonous spines! (this neat vid also shows a LOT of close up details)
Urchin Riders from liquidguru on Vimeo.
Some of the little buggers actually "hollow" out a space, clearing out spines where they can live! You can see the bare patch on this one...
Coleman shrimp
Tiny Shrimp
Image by Klaus Stiefel
In addition to all the various crustaceans, Amazingly. Here is a benthic ctenophore (which I've written about here) ON A FIRE URCHIN!! (the white blobby bits are the feeding tentacles)  Mind. blown!!  and incidentally.. a likely first occurrence recorded....
Ctenophore on a Fire Urchin
Image by Mark Atwell


Anna D. said...

Benthic ctenophores on fire urchins - w00t! I always learn from your blog!

ChrisM said...

That was quite a neat one to find! I think that's a new record...

stone said...

Cool!Very beautiful! Thanks for your sharing!