Description: A large chiton (up to 60 mm) with a relatively broad girdle that is densely covered in thick, coarse spines. The spines are arranged in 18 conspicuous tufts of bristles that can be up to 1.5 mm long. The girdle is covered with densely packed recumbent spines, making it feel velvety to touch, and densely fringed with longer spines. The overall shape is an elongate oval. Colouration is highly variable and can be anything from grey, off-white, yellow, green, brown and even shades of blue, in a marbled pattern. They have strongly arched valves and well-pronounced beak.

Habitat: Found from the lower shore to the sublittoral, hard substrata such as boulders, cobbles etc.

Distribution: There has historically been some confusion over the taxonomy and therefore distribution of the Acanthochitona spp. in Britain and Ireland. DNA barcoding has suggested Acanthochitona discrepans is a northern species and that Acanthochitona crinita has a much broader range. Acanthochitona fasicularis appears to be more southern.

Similar Species: Could be confused with Acanthochitona crinita or Acanthochitona discrepans.

Key Identification Features:

• Large chiton up to 60 mm.
• Girdle has 18 dense tufts of coarse spines.
• Girdle is densely covered in recumbent spines giving it a velvety feel.
• Valves strongly arched with a pronounced beak.

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

iNaturalist: Acanthochitona fascicularis at iNaturalist World Species Observations database.

GBIF data for Acanthochitona fascicularis

WoRMS: Acanthochitona fascicularis at World Register of Marine Species. Accepted name: Acanthochitona fascicularis (Linnaeus, 1767). AphiaID: 138677.

Classification: Biota; Animalia; Mollusca; Polyplacophora; Neoloricata; Chitonida; Acanthochitonina; Cryptoplacoidea; Acanthochitonidae; Acanthochitoninae; Acanthochitona