hugabug 3: Sea cucumbers puke their guts out

Above: photo by Graeme A. Barber
Below: Byrne 2001 (Journal of Experimental Biology)

The internal organs of a sea cucumber explode out of its body, and the sea cucumber survives.
Listen to find out how and why.

Right-click or Command+click to download

Music in this show:
1. Sara Tavares, “Sumanai”
2. Bernie Krause, “Fish wrap”
3. from Donald in Mathmagic Land
4. Spanglish Fly, “Let my people bugalú” (Clay Holley and Jeff Dynamite remix)
5. Battles, “Inchworm”

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Actually, a sea cucumber explodes repeatedly in the 10 years it’s alive. And all of its guts regenerate.

Two things can happen. Scenario 1: A sea cucumber is wandering around on the sea floor. A predator attacks, and the sea cucumber pukes up all of its guts, maybe tangling the enemy in a sticky mess of intestines, or the predator may be distracted by the free meal of delicious entrails, allowing the empty sac of sea cucumber skin–still alive!–to crawl away to safety.

Scenario 2: A sea cucumber has been living its life on the sea floor for yet another year. Maybe poop wastes have filled the nooks and crannies of its digestive system. Maybe an uncomfortable number of parasites have invaded the sea cucumber’s internal organs. Maybe the guts are just old enough, now, to be discarded.

First, the sea cucumber stops eating. It gets all lazy and sits around instead of being active. Then, the front end of the sea cucumber expands like a balloon, as muscle spasms push all the intestines and repiratory organs and gonads all up into the front of the body, and BOOM! The front end of the sea cucumber pops like a piñata full of guts. Either that, or sometimes, BOOM! All the guts just spill out of the sea cucumber’s butt.

What’s crazy is that this is not a destructive process.

from Alvarado 2000 (Bioessays)

More muscle contractions seal off the explosion holes, and the sea cucumber rests for about a month, while its internal organs regenerate. And there you have it. The sea cucumber is alive another day with a brand new, clean set of organs. And it starts eating again.

Along similar lines, did you know that a starfish pukes up its stomach to eat? A starfish will approach another animal that looks delicious–sometimes a sea cucumber, sometimes a clam or a mussel–and just kind of sit on the creature. That way, the starfish mouth is pressed up against its prey. The starfish wraps a delicious creature in the pouches of its regurgitated stomach. It oozes digestive juices, rendering its prey a blob of mostly-digested flesh. Then, the starfish eats its own stomach again, and the stomach folds up and tucks back into the starfish’s mouth.

Now, let’s say the starfish stomach gets caught on the rough edges of a mussel shell and tears off or gets damaged. Like the sea cucumber, a starfish can regenerate its own stomach.

Not only that–some species of sharks also can puke up their stomachs if they accidentally bite into any “large objects of dubious digestibility” [1]. These visceral acrobatics involve the shark turning its own stomach inside-out and pushing the stomach through its mouth. Once the accidentally eaten boot (or whatever) is expelled, the stomach can be pulled back into place, into the belly of the beast.

And some sharks, like the hammerhead–from time to time, it expels its intestines through its butt, then pulls those guts right back in through the anus.

But anyway, the point is–the extraordinary sea cucumber explodes its guts out and lives to tell the tale.

You may be wondering, “How come people can’t do that?” Well, to some extent, a very small extent, we actually can, sort of. Our livers are pretty good at regenerating after injury. More experiments with sea cucumbers may lead to human health discoveries. For example, the sea cucumber digestive tube expresses a couple genes associated with cancer and tumor growth in humans. By figuring out how gut regeneration stops in sea cucumbers once their guts are fully formed, maybe we can stop tumors from growing in human cancer patients.

from Brockes 1997 (Science)

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Don’t miss this crazy stuff elsewhere on the internet:

The music is unfortunate, but the visuals are awesome in this video of a sea cucumber gut piñata exploding. Just put it on mute and provide a personalized soundtrack.

There are so very many things to learn about starfish (sea stars, if you prefer). For instance:
Time-lapse movie of a starfish feeding on the side of an aquarium
– Front-row seat for the regurgitation of a starfish stomach–the view from the inside of a mussel shell
– Grisly time-lapse footage of starfish and other creatures feasting on a dead seal
Pure entertainment with photoshop

from J. Arthur Thomson, (The Outline of Science, Vol. 1)

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[1] ^ An article by Eugenie Clark (a.k.a., The Shark Lady). Clark, E. 1992. Whale sharks: gentle monsters of the deep. National Geographic, 180(6):120-139.

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