Capitellidae

Capitellidae is a family of marine polychaete worms belonging to the order Capitellida. These segmented worms are found in a wide range of marine environments, from shallow intertidal zones to deep-sea habitats, and are common in soft sediments. Members of this family are often characterized by their distinctive morphology, which includes a highly modified anterior end and a posterior end adapted for burrowing.

A key feature of many capitellids is the presence of a prostomium that is often small and lacks appendages like antennae or eyes. The body is typically divided into two distinct regions: a thoracic region with short, chaetae-bearing segments and an abdominal region with longer, more numerous chaetae. Some species exhibit a significant change in body shape and chaetal types between these regions, a phenomenon known as sexual dimorphism. Their feeding habits are varied, with many species being deposit feeders, ingesting sediment to extract organic matter.

Capitellidae plays an important role in benthic ecosystems, contributing to nutrient cycling and sediment bioturbation. They are often found in high densities, making them a significant component of the infaunal community. Due to their abundance and sensitivity to environmental changes, certain species are sometimes used as bioindicators of pollution or habitat disturbance. The family is diverse, with numerous genera and species described globally.