Simple Summary
This study reports the first documented association of the marine polychaete Amphitrite cirrata with the red king crab (Paralithodes camtschaticus) in the Barents Sea. Previously known as a widely distributed tube-building worm inhabiting various marine substrates, Amphitrite cirrata has not been recorded as an associate of marine animals. This finding sheds new light on the evolving symbiotic relationships in the red king crab’s introduced range. The worms were found in the gills of red king crabs, causing tissue damage and contamination with sand and organic waste, which may impair the crab’s respiration and molting abilities. While Amphitrite cirrata benefits from the host environment through access to food, protection, and dispersal, it represents a potential parasitic threat to host health.
Abstract
The introduced red king crab Paralithodes camtschaticus holds significant commercial value in the Barents Sea. This species is recognized as a host for a wide variety of symbiotic organisms, including polychaetes. In July 2015 and 2025, a total of 12 specimens of the marine terebellid polychaete Amphitrite cirrata were discovered inhabiting the gills of two red king crabs in Dalnezelenetskaya Bay, Barents Sea. This study represents the first documented occurrence of an association between these benthic species. Colonization of the red king crab by Amphitrite cirrata offers several advantages to the polychaetes by providing access to suitable feeding conditions, increased mobility, and protection from potential predators. However, this association poses disadvantages to the host crabs, as it results in tissue damage and an elevated concentration of sand particles within their gills.