Bottomdwelling

Bottom-dwelling, or benthic, organisms live on, in, or near the seabed, riverbed, or lakebed. The term contrasts with pelagic species that inhabit the water column away from the bottom. Benthic life encompasses a wide range of organisms, including sessile sponges and corals, as well as mobile fish, crustaceans, and mollusks.

Habitats span oceans, seas, rivers, and lakes. Some bottom-dwellers are infauna that burrow beneath the sediment, while others are epibenthic and move across or crawl along the substrate. Substrate type—sand, mud, gravel, or rock—shapes the community and the available food sources. Many species prefer shallow coastal zones, while others inhabit the deep ocean.

Adaptations common to bottom-dwellers include flattened bodies or a low profile to resist currents, sensory structures for detecting chemicals and vibrations, and specialized appendages for burrowing, walking, or gripping the substrate. Feeding strategies vary: detritivores ingest organic matter on or in the sediment, filter feeders extract particles from water, scavengers feed on dead material, and predators hunt on or near the bottom.

Ecologically, benthic communities process nutrients, recycle organic matter, and influence sediment structure and oxygen dynamics. They support commercial fisheries and aquaculture when target species are bottom-dwellers. Human impacts such as bottom trawling, dredging, pollution, and climate-driven oxygen loss threaten these communities and can alter sediment chemistry and habitat complexity.