Science Snapshot: Sea Star

The above image may look like a scaly white mouth opening up to reveal tons of tiny bubblegum pink tongues, but it is actually a starfish! More specifically, this is the ventral (stomach) side of the starfish arm. I took this picture at an aquarium here in Utah, the Loveland Living Planet aquarium. When I saw the starfish pressed up against the glass showing off its crazy unique anatomy, I geeked out, grabbing my camera phone with macro lens attached and snapped some pictures. Though this may look like a mouth, it is not… well it actually could be considered a mouth. The sea star uses the underside of its arms to aid in the digestion of prey.


Some starfish enjoy snacking on oysters. But wait, how on earth can that barely mobile sea star with no apparent mouth break through the armor of an oyster?! I am glad you asked! The sea star will wrap its entire body around the oyster and, with all the might it can muster, open the oyster ever so slightly. All it needs is a slight crack of an opening, then it jams its tube feet (the tiny pink tentacles reminiscent of tongues in the above image) into the oyster and makes room for one of its two stomachs to infiltrate the oyster and digest its insides. Let me rephrase that in case you missed the peculiar phenomena just explained to you… THE STARFISH SPITS OUT ONE OF ITS TWO STOMACHS INTO THE OYSTER TO DIGEST THE OYSTER FROM THE INSIDE OUT! That is crazy, right?! Its tube feet then aid in the retraction of the stomach and the gathering of the newly digested oyster.


Another sea star fun fact… if for some reason one of its five arms was severed at the center disk of the starfish, it can regenerate a new arm. But wait, it gets better. If that dislocated arm has a part of the center disk still attached, it will grow a whole new starfish from just that one arm! These new starfish are merely clones (exact copies) of the original starfish, but still an amazing adaptation. Two starfish for the price of one severed arm. Watch out Star Wars, there is a new kind of clone wars afoot and it has to do with a massive army of starfish clones!


If you read this whole blog post, you are my hero! Thanks for reading. Please feel free to leave me a comment and feedback below. Also, let me know if there is any particular science topic you would like me to look at “through green tinted glasses” and I will write about it.

*All of the photography in this post was taken by me, Jay Merrill.


2 thoughts on “Science Snapshot: Sea Star

  1. Fascinating. But yuck. Some will go to any lengths to eat raw oysters.

    But it’s also an interesting example of the continual evolutionary “arms race” between eater and eaten, hunter and hunted. Oysters evolve tougher shells, starfish evolve injectable stomachs.



    1. Thanks for the comment! Absolutely an example of the evolutionary arms race. We don’t see it because we are a very recently evolved species and we have virtually no competition for survival. But species all over the world have been apart of this tug-o-war for thousands of years!


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