Strange ‘stacking’ behaviour seen in vent snails

A short paper describing the strange behaviour of forming hanging ‘stacks’ exhibited by the vent snail genus Gigantopelta has been published in the journal Plankton and Benthos Research! This behaviour is probably related to reproduction. The paper is open access and available for view here: https://doi.org/10.3800/pbr.13.25“Mating stacks” have been widely documented in calyptraeid slipper limpets, which are protandric and exhibit sequential hermaphroditism. Gigantopelta is a genus of peltospirid snails endemic to deep-sea hydrothermal vents containing two species, one distributed on the East Scotia Ridge in the Southern Ocean and another on the Southwest Indian Ridge in the Indian Ocean. Here, we report the observation that both species form extensive (often >15 individuals) “snail chains”. These chains are potentially analogous to ‘mating stacks’ of calyptraeids, or alternatively, maybe a behaviour to facilitate spermatophore transfer. Both Gigantopelta species apparently have separate sexes and are sexually mature at a small size. However, it remains unclear whether they undergo sex change during their life.

Snail chains formed by Gigantopelta chessoia (left) and G. aegis (right)