Is it sex in chains? Potential mating stacks in deep-sea hydrothermal vent snails

Abstract

Abstract: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.

From wood to vent: first cocculinid limpet associated with hydrothermal activity discovered in the Weddell Sea

“…This is reminiscent of ‘mating stacks’ documented for the Antarctic true limpet Nacella concinna (Strebel, 1908), which spawn in temporary stacks to increase fertilization success (Picken & Allan 1983) or more permanent stacking in calyptreid slipper limpets, which are protandric hermaphrodites (Cledón et al 2016). As cocculinids exhibit internal fertilization (Haszprunar 1987, 1988), stacking may represent a behaviour to facilitate copulation, as has been speculated for the vent-endemic gonochoristic peltospirid snails in the genus Gigantopelta , which are also internal fertilizers (Chen et al 2018a). Stacking has also been observed in the vetigastropod vent limpet Lepetodrilus fucensis , which live in extreme densities as high as 300 000 individuals per m 2 , although in this case access to food particles has been hypothesized as the purpose for stacking behaviour (Bates et al 2005).…”

A Global Red List for Hydrothermal Vent Molluscs

“…Molluscs represent one of the dominant groups in vent habitats, with good global coverage and a large degree of vent-endemism (Wolff, 2005;Chapman et al, 2019). As important members of the vent community, they inhabit an array of niches including hosting endosymbiotic bacteria in specialized organs (Chen et al, 2018a), forming dense aggregations that provide substrate for other species (Laming et al, 2018;Sun et al, 2020), and exhibit unique ecological traits (e.g., Chen et al, 2018b).…”