What defensive behavior lets some sea cucumbers expel internal organs?

The defensive behavior that lets some sea cucumbers expel internal organs is called evisceration.

When threatened, certain sea cucumbers force out parts of their digestive tract or other internal structures through the anus or a rupture near the rear of the body. The expelled material may distract or entangle a predator, while toxic compounds can make the animal less appealing to attack. The sea cucumber later regenerates the lost organs.

Evisceration is not universal across all sea cucumbers, and the exact organs released vary by species. Some species also discharge sticky defensive tubules called Cuvierian tubules. This behavior should not be confused with autotomy, the deliberate shedding of a body part such as a lizard’s tail. Sea cucumbers are echinoderms, related to sea stars and sea urchins, but their soft, elongated bodies make them look very different from those relatives.