Species description: This worm lives in a white, chalky tube, usually with two parallel ridges on either side of the midline. If it is growing unsupported these distinctive ridges may be absent so caution is required when identifying. It is 4 mm wide and at least 45 mm long.

Habitat: On hard substrata in ports, marinas and harbours. Can also be found on the shore on stones and boulders.

Distribution: So far all records from Britain and Ireland are from the south of England.

Similar Species: Could be confused with other species of tube worm, including some Spirobranchu and other species of Hydroides, although most of these lack the parallel ridges. Examination of features on the animal itself (verticil and collar chatae especially) is required to be sure of identification.

Key Identification Features:

• White, chalky tube at least 45 mm long.
• Two parallel ridges on the tube either side of midline.

Distribution Map from NBN: Hydroides ezoensis at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Hydroides ezoensis at iNaturalist World Species Observations database.

WoRMS: Hydroides ezoensis at World Register of Marine Species. Accepted name: Hydroides ezoensis Okuda, 1934. AphiaID: 131003.

Classification: Biota; Animalia; Annelida; Polychaeta; Sedentaria; Canalipalpata; Sabellida; Serpulidae; Serpulinae; Serpulini; Hydroides