Holothurians have a body wall of mutable collagenous tissue whose stiffness is under nervous control. When the animal is handled roughly, attacked or subjected to poor conditions, that tissue can be softened at specific points so the wall parts and internal organs are forced out through the anus or a body wall rupture.
The expelled mass distracts or entangles a predator, and in some species it is sticky. Regeneration follows: the animal rebuilds gut and associated organs, with reported recovery times in the range of weeks to a few months depending on species, temperature and food supply.
Evisceration is often conflated with the sticky white Cuvierian tubules deployed by some tropical sea cucumbers, which are a different structure and not present in every group. It is also sometimes described as suicidal; it is not, since survival and regrowth are the normal outcome. What remains debated is how much of the response is defensive versus a seasonal or stress-driven physiological reset.