''Acanthodoris pilosa'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary t ...

, a dorid

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to matc ...

, a shell-less

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Onchidorididae Onchidorididae are a taxonomic family of sea slugs, dorid nudibranchs, marine gastropod molluscs in the superfamily Onchidoridoidea.Thompson, T. E., & Brown, G.H., 1984Biology of opisthobranch Molluscs.Vol. 2. Ray Society; London. 1-229, p.49 G ...

. 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 The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi language, Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a cha ...

Morro Bay, California Morro Bay (''Morro'', Spanish language, Spanish for "Hill") is a seaside city in San Luis Obispo County, California. Located on the Central Coast (California), Central Coast of California, the city population was 10,757 as of the 2020 United St ...

Description

''Acanthadoris pilosa'' grows to a length of about , or occasionally as much as . It gives the impression of being fluffy because the body is covered with long, fleshy pointed papillae. At the head end are two

rhinophore A rhinophore is one of a pair of chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, marine gastropod opisthobranch mollusks such as the nudibranchs, sea har ...

s, 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.

Distribution

This species was first described from Norway. It has been reported from the North

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

on both the American and European coasts, and from the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

.Rudman, W.B., 1999 (August 22
''Acanthodoris pilosa'' (Abildgaard in Muller, 1789).
n/nowiki> Sea Slug Forum. Australian Museum, Sydney. Specimens from

Cobscook Bay Cobscook Bay is located in Washington County in the state of Maine. It opens into Passamaquoddy Bay, within the Bay of Fundy. Cobscook Bay is immediately south of the island city of Eastport, the main island of which (Moose Island) straddles the ...

, Washington County,

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...

and Murles Point,

County Donegal County Donegal ( ; ga, Contae Dhún na nGall) is a county of Ireland in the province of Ulster and in the Northern and Western Region. It is named after the town of Donegal in the south of the county. It has also been known as County Tyrconne ...

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

have been sequenced for the

16S ribosomal RNA 16 S ribosomal RNA (or 16 S rRNA) is the RNA component of the 30S subunit of a prokaryotic ribosome (SSU rRNA). It binds to the Shine-Dalgarno sequence and provides most of the SSU structure. The genes coding for it are referred to as 16S rRNA ...

Histone H3 Histone H3 is one of the five main histones involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and a long N-terminal tail, H3 is involved with the structure of the nucleosomes of the 'beads on a stri ...

and CO1 genes.Hallas, JM and Gosliner, TM. (2015) ''Family Matters: the first molecular phylogeny of the Onchidorididae (Mollusca, Gastropoda, Nudibranchia).'' Molecular Phylogenetics and Evolution, 88: 16–27. It is common all round the British Isles in the shallow subtidal zone, at depths down to about . Reports of this species from

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

Baba, K. (1935
''The fauna of Akkeshi Bay. I. Opisthobranchia.''
Journal of the Faculty of Science, Hokkaido Imperial University, series 6, Zoology 4(3):115–125, pls. 7–8; page 119, pl. 7, figs 8–10. must be considered doubtful in the light of recent

molecular phylogeny Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

results which show that at least some of the animals from the North Pacific are '' Acanthodoris atrogriseata''.

Ecology

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

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

ns.

References

External links

{{Taxonbar, from=Q624354 Onchidorididae Gastropods described in 1789