Tuesday, December 10, 2013

SAND ANGELS! Astropecten The starfish that dig it!

Astropecten articulatus, Stafford Beach, Cumberland Island National Seashore, Camden County, Georgia 1
Image by Alan Cressler
So, y'a know how people do this snow thing? SNOW ANGELS?  Drop yourself in some powder and go wild!
Well, la-dee-da! Starfish can do that TOO! Except, not in snow. not in the winter. Not on land.  In sand. in mostly tropical shallow to temperate waters. So there.

I am referring to the widely known "sand star" called Astropecten, which includes over 100 species present all over the world, in tropical to temperate waters.   Go here to see some awesome pics of Japanese Astropecten and related spp. Most occur in shallows but some live in deeper-waters.
IMG_5929wa
Image by Kevin Bryant
Astropecten is often confused with Archaster typicus aka the "fake Astropecten" aka the "typical star" aka the "other sand star." Go here to see the difference. But one important difference? you will NEVER catch Astropecten pseudocopulating! Bfah!

Here's a nice image of Astropecten indicus from Singapore, illustrating the animal next to the star-shaped impression it makes in the sand.
Plain sand star (Astropecten indicus)
Image by Kok Sheng
Here is an excellent photo sequence of a species of Astropecten from Iran, showing a full range of sitting on the sand and burying itself.
Hiding Starfish
Image by Hamed Saber
Burial in Astropecten can be quite rapid. It accomplishes this via a combination of its pointed (rather than suckered) tube feet in conjunction with its many spines which are moveable and are used to help push itself into the sand. Astropecten is among the fastest of known starfish. 
Image below of an Astropecten from Singapore.
Orange sand star (Astropecten sp.)
Image by Wildsingapore. 
Pictures are nice. But why stop there?  Here's a quick 30 second video of Astropecten from Singapore burying itself and vanishing before your very eyes!
                               
Which famous Simpsons gif meme does Astropecten remind you of?

This one is probably one of the best videos of Astropecten burying and reburying itself. A video from the Enoshima aquarium of A. polyacanthus

Although they dig, they are not, strictly speaking, infaunal. They live buried right under the surface of the sand...
Astropectinidae>Astropecten Sea star 39
image by Bill & Mark Bell
Where, they are often digging through the sediment trying to find goodies to eat, such as this clam. But really whatever they find, they will swallow and devour. Note that Astropecten and its relatives LACK an eversible stomach (that you might see in other starfish). So they literally can ONLY swallow their prey..   This image is fr. A. aurantiacus in the N. Atlantic somewhere..
Prédation Astropecten aurantiacus

As I mentioned, Astropecten occurs widely around the world. And is quite diverse.  Here is Astropecten articulatus from Georgia (south coast of the US)
Astropecten articulatus, Stafford Beach, Cumberland Island National Seashore, Camden County, Georgia 1
Image by Alan Cressler
Astropecten sp. from Singapore. Cool racing stripes! 
Painted sand star (Astropecten sp.)
Image by Wild Singapore
Here's a pic of Astropecten latespinosus from Japan
Image by Yoichi Kogure! 
The substrate/sediment type can vary also.. Some live in very fine sediments, such as this Italian Astropecten, possibly A. irregularis
Piramidi_013
Image by comunerimini
Astropecten aurantiacus in sandy sediment...
Star Fish/ Astropecten aurantiacus
Image by Archipelagos Institute of Marine Conservation
Whereas others live in fairly coarse, sandy type sediments.. such as this Astropecten bispinosus from Greece.
Astropecten
Image by sarsifa
Astropecten sp. Not sure where this was taken..I think the Mediterranean? But again, coarse sediment.
Sea star , Astropecten sp.
Image by Dimitrious Poursanidis
Astropecten sp.
Image by Dimitrious Poursanidis
What's that you say? You wanted to see more fabulous video of Astropecten from around the world burying themselves in sand? YOU GOT IT.
                                     

                 

1 comment:

Aaron Carlson said...

Seriously? An entire blog devoted to Echinodermata?

I guess my only remaining question is: how am I just now learning about this?!

Awesome blog! I can't wait to dig into it.