Hengeidae

Hengeidae is a family of polychaete annelids within the order Phyllodocida. Members of this family are marine worms that occur in a range of habitats from shallow coastal waters to the deep sea, and they are distributed in temperate and tropical regions around the world. The group is recognized by a combination of features typical of errant polychaetes, including a segmented body with parapodia and chaetae, though specific arrangements and shapes vary among genera.

Morphologically, Hengeidae species tend to have elongated bodies with well-developed paired parapodia along much of the length of the trunk. Prostomial and first-segment features show variation between genera, and some species possess specialized appendages or lobe-like structures on the parapodia. Many members of the family are benthic and may construct mucous or lightweight tubes, or they may be free-living burrowers.

Ecologically, Hengeidae species fulfill roles as detritivores, micro-predators, or occasional filter-feeders, contributing to nutrient cycling in their ecosystems. They serve as prey for a variety of marine animals, and their presence can indicate aspects of sediment structure and water quality. Reproductive strategies are typically sexual, with free-swimming larval stages in many species, aiding regional dispersal.

Taxonomically, Hengeidae has been placed within Phyllodocida, but its exact relationships to other families within the order have been subject to revision as morphological and molecular data accumulate. The fossil record for the group is limited, which complicates assessments of its evolutionary history. Ongoing taxonomic work continues to refine the circumscription of the family and clarify intergeneric relationships within Hengeidae.