Sea cucumbers aren’t built for fleeing from predators. But they do have a trick up their sleeves – or more accurately, up their bottoms – for dealing with danger. And new research sheds light on why it is so effective.
Their secret weapon is called the Cuvierian organ. It’s a branch of the animal’s gills, which sit just inside the anus, that extends into the body’s interior.
When danger threatens, the gut wall ruptures and the organ is ejected through their rear ends.
On contact with seawater, it transforms into sticky, spaghetti-like threads that immobilise assailants.
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The new PNAS study shows that the threads are built of proteins similar to those found in spider silk.
These are so strong and sticky that no predators seem to have come up with a way of dealing with them, says Ting Chen of China’s South Sea Institute of Oceanology.
“Interestingly, as a counter-adaptation, most predators have given up hunting sea cucumbers.”
Main image: Black sea cucumber (Holothuria leucospilota) © Philippe Bourjon – some rights reserved (CC BY-SA) https://creativecommons.org/licenses/by-sa/4.0/