Stolidobranchia

Stolidobranchia is an order of marine annelid worms belonging to the class Polychaeta. These segmented worms are characterized by their sedentary lifestyle and the presence of a pharyngeal pouch lined with chitin. Members of Stolidobranchia are often found burrowing in soft substrates like sand and mud, or within tubes they construct themselves. They are suspension feeders, using their feathery appendages, known as parapodia, to capture small particles of food from the water column.

The morphology of stolidobranchs typically includes a distinct head region with sensory structures, although these can be reduced in some species. Their bodies are segmented, with each segment bearing parapodia equipped with chaetae, which are bristles used for locomotion and anchoring. Reproduction in Stolidobranchia generally involves external fertilization, with sexes being separate or hermaphroditic. Larval stages are planktonic before settling to the benthos to develop into adults.

This order encompasses a diverse range of species found in marine environments worldwide, from intertidal zones to deep-sea habitats. Common examples of stolidobranchs include the lugworms and the beard worms, though the latter are sometimes placed in their own separate class. Their ecological role is significant, as they contribute to bioturbation, the disturbance of sediments, and serve as a food source for various marine animals.