endobenthos

Endobenthos are organisms that inhabit the interior of sediments on the bottom of aquatic environments, particularly the sea floor. They form a key part of the benthic zone and live within the substrate rather than on its surface (epibenthos) or in the overlying water column. Endobenthic life includes a diversity of infaunal taxa such as polychaete worms, bivalves, crustaceans, nematodes, and other small invertebrates.

Endobenthic communities occupy sediment layers from shallowly buried zones to deeper burrow networks. They are adapted to variable sediment textures, moisture, and oxygen conditions; many create burrows, tubes, or galleries, while others are mobile within the sediment. Their distributions are found in both marine and freshwater sediments across a range of depths, from coastal to deep-sea environments.

Ecologically, endobenthos contribute to bioturbation and bioirrigation, mixing sediments and enhancing the exchange of nutrients and oxygen between the sediment and overlying water. They influence microbial activity, organic matter degradation, and carbon cycling, and they often serve as prey for higher trophic levels. Because their community structure responds to environmental conditions, endobenthos can serve as indicators of sediment health, pollution, and habitat stability.

In research, endobenthos are studied to understand ecosystem function and past conditions. Sampling methods include sediment cores and grabs followed by sieving to quantify abundance and community composition at different sediment horizons. Endobenthos are distinguished from epibenthos (on surfaces) and hyperbenthos (in the water column near the bottom).