Hediste

Hediste is a genus of marine polychaete worms in the family Nereididae, commonly known as ragworms or sandworms. The genus includes several species distributed in coastal and estuarine habitats worldwide, with a particular emphasis in temperate regions.

The best-known species is Hediste diversicolor, formerly described as Nereis diversicolor. It occurs in brackish and marine sediments, especially in estuaries and mudflats of Europe and parts of North America. Hediste diversicolor and related species are benthic and typically inhabit shallow burrows in soft substrates, where they contribute to sediment turnover and aeration.

Morphologically, Hediste worms have elongated, segmented bodies with numerous parapodia bearing chaetae (bristles). The prostomium carries sensory structures such as palps and often eyes. Size varies by species, ranging from a few centimeters to more than 10 centimeters in length, depending on age and environmental conditions.

Ecologically, Hediste species are active carnivores and detritivores that feed on small invertebrates and organic material within the sediment. They play important roles in benthic ecosystems by modifying sediment structure and serving as prey for fish and birds. Due to their sensitivity to pollution and their role in sediment processes, several species are used as bioindicator organisms in ecotoxicology and environmental monitoring. They are also widely used as fishing bait in some regions.

Taxonomically, Hediste belongs to Nereididae, and taxonomic revisions have moved certain species from other genera, such as Nereis, into Hediste, reflecting updates in polychaete classification.