Apophallation is the biting off of the penis, known to occur in
terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
slugs, which are
hermaphroditic
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many taxonomic groups of animals (mostly invertebrates) do not have s ...
gastropod mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
s. It has been reported in some species of banana slugs, ''
Ariolimax
Banana slugs are North American terrestrial slugs comprising the genus ''Ariolimax''. MolluscaBase eds. (2021). MolluscaBase. Ariolimax Mörch, 1859. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p ...
,'' and in the distantly related ''
Deroceras laeve''.
In the mating of banana slugs, the penis is inserted into the body of the partner. The penis may become trapped, perhaps because of the action of a special muscle, in which case the penis is gnawed off by either the partner or the owner. No replacement penis grows, but the apophallated slug can mate as a female.
It has been proposed that it might be adaptive for a slug to apophallate the mating partner because that partner is subsequently prevented from mating as a male and so might increase the allocation of resources to the production of eggs fertilised from the mating.
One paper reports that individuals of ''
Deroceras laeve'' sometimes after mating bite off their own penis, which is then eaten by the partner.
In this genus, sperm is swapped from penis to penis, so the amputee would not be able to mate successfully even in the female role.
References
External links
Reproduction in animals
Gastropod anatomy
Penis
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