Explanations for answers provided for function-of-evisceration quiz:

Ridding of waste matter.  Possibly.  There is no excretory system as such in sea cucumbers and the principal nitrogenous excretion, ammonia, readily diffuses out through the skin.  However, in some species that eviscerate, there are distinctive deposits in tissues around the gut termed “brown bodies”.  These are known in other animals and are thought to be associated with ageing and disease.  In earthworms, for example, similar-appearing brown bodies around the gut consist of masses of dead coelomocytes packed with bacteria and other “non-self” matter.

Diverting predators.  Yes.  Lab tests with sea-star predators (e.g., Solaster stimpsoni) attacking Eupentacta quinquesemita show that eviscerated guts successfully divert the predator from the sea cucumber, but only if there is a refuge for the sea cucumber to withdraw into.  Byrne 1985 Ophelia 24: 75.

Ridding of parasites.  No.   Sea cucumbers Eupentacta quinquesemita around Victoria, British Columbia often have shell-less snail parasites Thyonicola americana attached to their intestines.  The parasites extend into the coelomic cavity of the sea cucumber, can reach 2-3 times the length of the host, and may be in such numbers as to obliterate the entire coelomic space.  However, while 40% of individuals in the Victoria population are parasitised, no convincing correlation exists between parasite load and seasonal evisceration.  However, one point noted by the author is that parasitised individuals are more likely to eviscerate during collection and handling.  Byrne 1985 Ophelia 24: 75.

Reducing metabolic costs in adverse conditions.  This is unlikely.  The idea here is that, by eviscerating, the sea cucumber can shut down metabolically during winter when food is scarce.  However, in terms of costs/benefits, it doesn’t seem that it could be a useful strategy.  Mostly, the respiratory tree remains behind.  If metabolic shutdown were the aim, wouldn’t this part be discarded as well?

NOTE  lit. “body cavity cells” G.  These are defensive cells akin to our white blood cells.  They wander the main body (coelomic) cavity in echinoderms and phagocytise bacteria, and other unwanted organic and inorganic particles

Clearly, this topic is worthy of further research.