noun, plural in·fau·nas, in·fau·nae [in-faw-nee] /ˈɪnˌfɔ ni/. Ecology.
- the aggregate of animals that burrow into and live in the bottom deposits of an ocean, river, or lake.
- Benthic animals that live in the substrate of a body of water, especially in a soft sea bottom. Infauna usually construct tubes or burrows and are commonly found in deeper and subtidal waters. Clams, tubeworms, and burrowing crabs are infaunal animals. Compare epifauna.