The business end of a sea urchin

How's this for an amusing case of photographic mis-identification? Call it "Dueling Disgustingness". Last week, New Scientist posted this lovely image of a blue-spotted sea urchin, taken by nature photographer David Fleetham.

New Scientist identified the photo as depicting said sea urchin in the process of expelling its own guts out of its mouth. Which, gross, but okay. That's reasonable. A surprising number of underwater animals eat in this manner, using the acids in their guts to dissolve prey before they actually slurp it up as a slurry.

But, at the Echinoblog, Smithsonian invertebrate zoology researcher Christopher Mah makes a compelling case against New Scientist's interpretation. That's not actually the sea urchin's mouth, says Mah. In fact, it's the opposite. That's a (rare) photo of a sea urchin taking a dump.

Mah has a lot of good photos that make his case quite well. You should check them out. Then, join me in contemplating this thought: If Mah is right, doesn't sea urchin poop look a lot like Dippin' Dots?

The New Scientist blog post—featuring lots of cool info about sea urchins

Christopher Mah's analysis of the photo, explaining why he thinks it shows a pooping sea urchin, rather than one that is eating something.

David Fleetham's website—for more (less disgusting) photos of nature

Via Scicurious


  1. If it takes a team of experts to distinguish between your mouth and your ass, then maybe it’s time to rethink your place in the universe.  This should be a wake up call to sea urchins everywhere.

  2. That view of an urchin reminds me of a mille fiore glass sculpture an the Dippin’ Dots line  almost  made me upchuckle.

  3. I LOVE the Dippin’ Dots comparison. I do a lot of urchin feeding trials and clean a lot of urchin poop. For purple and red urchins in California, their poop pretty looks more like confetti. One of my favorite trials (yes, I’m the kind of guy that has his favorite urchin pooping trials) involved one suite or urchins that were fed the red alga Rhodymenia. Their poop came out almost fluorescent red. After a few days away, it looked like these little purple spiky guys were wandering around their cages after a psychedelic ticker-tape parade.

    This may be more than you ever wanted to know about urchin poop.

  4. Well that’s the same opening, so both are right….I’m not even sure a sea urchin has a digestive tract, so eating and excreting might be the same act, just in different directions.

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