Definition: an animal that excavates holes or tunnels into soil or benthic sediment to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Inhabited burrows function as a refuge, protecting the inhabitants from predation and environmental extremes. They provide physical support for the digging and feeding activities of the burrow inhabitants. The harsh chemical environment deep in aquatic burrows must be counteracted by active or passive irrigation of burrow water.
Definition: aquatic consumers oriented head-down in sediments, where they feed at depth and transport sediment through their guts to the sediment surface. Major upward-conveyor groups include burrowing polychaetes like the lugworm, Arenicola marina, and Thalassinid shrimps.