Hairy spiny doris (Acanthodoris pilosa)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Mollusca · Class: Gastropoda · Order: Nudibranchia · Family: Acanthodorididae · Genus: Acanthodoris.

Accepted name: Acanthodoris pilosa · Authority: (Abildgaard, 1789) · Taxonomic status: accepted · AphiaID: 140627.

Synonyms and superseded combinations recorded for this taxon: Acanthodoris citrina A. E. Verrill, 1879; Acanthodoris ornata A. E. Verrill, 1879; Acanthodoris pilosa var. albescens Bergh, 1880; Acanthodoris pilosa var. purpurea Bergh, 1880; Acanthodoris subquadrata (Alder & Hancock, 1845); Doris bifida A. E. Verrill, 1870; Doris flemingii Forbes, 1838; Doris laevis J. E. Gray, 1850; Doris nigricans J. Fleming, 1820; Doris pilosa Abildgaard, 1789; Doris quadrangulata Jeffreys, 1869; Doris rocinela Leach, 1852; Doris similis Alder & Hancock, 1842; Doris stellata Gmelin, 1791; Doris sublaevis W. Thompson, 1840; Doris subquadrata Alder & Hancock, 1845.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=140627 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Acanthodoris pilosa. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 2 cm · Depth range: 0–55 m · Habitat zone: benthic · Vulnerability index: 10 of 100.

SeaLifeBase notes: Assumed maximum length from Ref. 822. This species is found in infralittoral areas particularly in gulfs and estuaries. It is known as an omnivore, predator and a scavenger. It feeds on planktonic and minute detrital food items through either suspension or deposit feeding (Ref. 87872).

Source: SeaLifeBase species summary (SpecCode 7809) — https://www.sealifebase.se/summary/Acanthodoris-pilosa.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

3,669 georeferenced occurrence records for Acanthodoris pilosa are published through GBIF from 19 countries or marine areas. The map above plots 207 distinct locations from a sample of 3,000 records, omitting 134 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: United Kingdom of Great Britain and Northern Ireland (1,918); Norway (441); Canada (291); Netherlands (250); Ireland (234).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 2292107) — https://www.gbif.org/occurrence/search?taxon_key=2292107&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=140627 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

It is found in shallow water in the northeastern Atlantic Ocean, its range extending from Norway to France, and also both on the eastern coast of Canada and the United States, and the Pacific coast from the Aleutian Islands to Morro Bay, California.

Acanthadoris pilosa grows to a length of about 3 cm, or occasionally as much as 7 cm. It gives the impression of being fluffy because the body is covered with long, fleshy pointed papillae. At the head end are two rhinophores, much larger than the papillae, which house the sensory organs; these typically are bent towards the rear of the animal. At the posterior end there is a distinctive ring of up to nine gills. This sea slug has a uniform colour which may be anything from whitish to pale purplish-brown to darker brown or charcoal grey. Juveniles are often speckled.

This species was first described from Norway. It has been reported from the North Atlantic Ocean on both the American and European coasts, and from the Pacific Northwest. Specimens from Cobscook Bay, Washington County, Maine and Murles Point, County Donegal, Ireland have been sequenced for the 16S ribosomal RNA, Histone H3 and CO1 genes. It is common all round the British Isles in the shallow subtidal zone, at depths down to about 80 m.

Reports of this species from Japan must be considered doubtful in the light of recent molecular phylogeny results which show that at least some of the animals from the North Pacific are Acanthodoris atrogriseata.

This nudibranch is found on rocks and other hard substrates and feeds on encrusting bryozoans.

Source: Wikipedia: Acanthodoris pilosa — https://en.wikipedia.org/wiki/Acanthodoris_pilosa (CC BY-SA 4.0). Accessed 2026-09-23.

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