epifaunal

Epifaunal refers to animals that live on the surface of the seabed or other submerged substrata, rather than within the substrate (infauna) or while swimming (nekton). Epifaunal organisms occupy the outermost layer of the bottom or attach to hard substrates, vegetation, or debris, forming communities on rocks, shells, corals, and man-made structures.

Epifauna can be sessile or mobile. Common sessile examples include barnacles, bryozoans, bryozoan-encrusted shells, ascidians (sea squirts), sponges, and some encrusting corals. Mobile epifauna include sea stars, sea urchins, crabs, shrimp, snails, and other organisms that move over the surface of the substrate. Epifaunal communities also inhabit interfaces such as kelp holdsfasts, seagrass leaves, and mangrove roots, as well as artificial substrates like piers and ships’ hulls.

Ecologically, epifauna play important roles as filter feeders and grazers, as habitat formers, and as prey for other organisms. Their distribution reflects substrate type, water energy, depth, and food availability. High-energy environments often favor robust, encrusting or fast-moving epifauna, while sheltered areas support a greater diversity of sessile forms. Epifaunal assemblages are sensitive indicators of environmental change, including pollution, sedimentation, and habitat disturbance.

In research and management, epifaunal communities are studied alongside infaunal and nektonic groups to assess habitat quality, biodiversity, and ecosystem function. They are also important considerations in biofouling, aquaculture infrastructure, and the design of marine substrates.