vesicomyids

Vesicomyidae is a family of saltwater clams (bivalves) that inhabit deep-sea chemosynthetic ecosystems. Members are best known from hydrothermal vents and cold seeps, but some species occur in sediments along continental margins. They range from small to moderately large clams and have elongated shells. Adults typically attach to substrata by byssal threads and extend long siphons to filter water for respiration and feeding while partly buried in the sediment or attached to structures.

Key feature is their symbiotic relationship with bacteria housed in the gills. These sulfur-oxidizing bacteria provide nutrients to the host through chemosynthesis, allowing vesicomyids to thrive where light-driven food production is absent. The clams also filter-feed, but the symbionts supply a major portion of their energy.

Life cycle and reproduction: Most vesicomyids release free-swimming larvae that disperse before settling, although species vary in their development. They have a worldwide distribution, with many species concentrated at deep-sea vents and seeps in the Pacific and other oceans.

Ecology and significance: Vesicomyids contribute to vent and seep communities by shaping microbial and macrofaunal habitats, and their shells and bodies provide resources for other organisms. They are important model systems for studying host–symbiont interactions and adaptations to extreme, chemosynthetic environments.