''Thyonicola dogieli'' is a

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

species of

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Eulimidae. It parasitises sea cucumbers in the northeastern Pacific Ocean.

Description

This slender elongated mollusc does not have a shell and takes the form of a long tube, coiled like a spring, or tied in knots, and filled with eggs. It holds the record as the longest gastropod mollusc in the world, one individual having been found to be long when uncoiled.

Ecology

''Thyonicola dogieli'' is a parasite of sea cucumbers such as '' Cucumaria miniata''. It inhabits the gut of the sea cucumber, being attached at the anterior end. It has no digestive tract and absorbs nutrients through its

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. It is a

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

; the

testis A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

is located near the anterior end and the ovary near the posterior end (this enables the sperm to be carried to the eggs amid the flow of the contents of the host's gut). The body is filled with maturing eggs enclosed in cocoons. When the

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod taxono ...

larvae, which have miniature coiled shells and operculums, are sufficiently developed, the cocoons are released into the sea cucumber's gut and pass out into the sea with its faeces. On encountering sea water the cocoons burst open and the free-living larvae are liberated. They are about long, and unless swallowed by a sea cucumber, they will soon die, However, any that are ingested undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

in the host's gut, lose their shell and mantle and burrow into the wall of the gut with the aid of a glandular secretion. As the juvenile mollusc grows, its posterior end pushes its way into the sea cucumber's body cavity, and the gonads develop, the interior of the mollusc becoming a brood pouch.

References

{{Taxonbar, from=Q14491853 Eulimidae Gastropods described in 1945