Velvety mail shell (Acanthochitona fascicularis)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



Acanthochitona fascicularis is an oval-shaped chiton with a flattened elongated body 6 cm in length. Its width is half that of its length. The body is protected by a shell composed of eight interlocked transverse, coarsely keeled plates or valves. The valves on the shell are strongly arched and, when viewed under a hand-lens, appear coarsely granular due to densely packed and evenly arranged dorsal papillae. The colour varies; marbled with off-white, grey, yellowish or brown. This species has a broad and spiny girdle with 18 dense tufts of long bristles (up to 1.5 mm long), four of which are in an arc around the head valve. The surface is covered with recumbent spines, making it feel velvety to the touch. The girdle is fringed with spines, up to 1 mm in length. 

Recorded distribution in Britain and Ireland

This species is probably under-recorded. Recorded from Kent, south-east coast of England; Lyme Bay south Devon coast; south Wales north to Angelsey; South Uist, Outer Hebrides; and Galway Bay and Lough Hyne, Co. Cork.

Global distribution

Recorded from northern Norway, the west coasts of the British Isles, the English Channel and north-west France, south into the Mediterranean and the Black Sea.


This chiton is found on the lower shore to 50 m depth, on rocks, boulders or in crevices.

Depth range

Lower shore - 50 m

Identifying features

  • Flat, extended oval shape, with eight transverse shell valves on the dorsal surface.
  • Girdle has 18 dense tufts of long bristles/spines, up to 1.5 mm long.
  • Up to 6 cm in length and width is half its length.
  • Variable colouration; marbled with off-white, grey, yellowish or brown.
  • Feels velvety to touch due to recumbent spines on its shell surface.

Additional information

'Coat-of-mail' shells (chitons) get their name from the armoured appearance of the valves like links in chain mail. This species is larger than Acanthochitona crinita but the two are very similar and therefore easily confused. Acanthochitona fascicularis has finer shell valves with more regular granulation. This species is a grazer, feeding on encrusting or filamentous algae and possibly bryozoans.

Listed by

- none -


  1. Crothers, J. A., 1997. A key to the major groups of British marine invertebrates. Field Studies, 9, 1-177.

  2. Gibson, R., Hextall, B. & Rogers, A., 2001. Photographic guide to the sea and seashore life of Britain and north-west Europe. Oxford: Oxford University Press.

  3. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

  4. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  5. Jones, A.M. & Baxter, J.M., 1987b. Molluscs: Caudofoveata, Solenogastres, Polyplacophora and Scaphopoda. Avon: The Bath Press. [Synopses of the British Fauna No. 37.]

  6. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.


  1. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: accessed via on 2018-09-25.

  2. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: accessed via on 2018-09-25.

  3. Fenwick, 2018. Aphotomarine. Occurrence dataset Accessed via on 2018-10-01

  4. Kent Wildlife Trust, 2018. Biological survey of the intertidal chalk reefs between Folkestone Warren and Kingsdown, Kent 2009-2011. Occurrence dataset: accessed via on 2018-10-01.

  5. Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: accessed via on 2018-10-01.

  6. National Trust, 2017. National Trust Species Records. Occurrence dataset: accessed via on 2018-10-01.

  7. NBN (National Biodiversity Network) Atlas. Available from:

  8. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-25

  9. South East Wales Biodiversity Records Centre, 2018. SEWBReC Molluscs (South East Wales). Occurrence dataset: accessed via on 2018-10-02.


This review can be cited as:

Rowley, S.J. 2008. Acanthochitona fascicularis Velvety mail shell. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25-05-2024]. Available from:

Last Updated: 03/06/2008