P.A. Gainey, P.E. Tompsett and S.M. Turk
The Crustacea includes the barnacles, crabs, lobsters, prawns and shrimps as well as many less well-known groups. Gainey and Turk, in Spalding, (ed.) 1997, have previously reviewed the crustacean fauna present around the Cornish coastline and the Isles of Scilly. The systematic sequence follows that used by Howson & Picton (1997) but a simplified nomenclature is followed and the groupings vary according to treatment. The Crustacea show a diverse range of body forms and life styles. Some also have representatives in freshwater and on land (these are discussed in the terrestrial section). None of the Cornish marine crustaceans are included in Bratton (1991). Distribution and habitat notes are from the cited references combined with details from the ERICA database, the local knowledge of the authors and further information from Smaldon, 1993; Ingle, 1996; Ingle & Christiansen, 2004; Mauchline, 1984; Marine Biological Association, 1957 and Southward, 2008. Information received since 1996 has been incorporated but many of the less well-studied groups can be regarded as data deficient. The assistance of Dr R.N. Bamber is gratefully acknowledged for certain groups. Decapoda, Copepoda (part 4.2), Cirripeda and Stomatopoda (part) by P.A. Gainey; Copepoda (part 4.1), Cladocera, Amphipoda, Cumacea, Euphausacea, Isopoda, Leptostraca, Mysidacea, Ostracoda and Stomatopoda (part) by P.E.Tompsett and S.M. Turk.
1. Water-fleas (Cladocera)
Water-fleas are mainly freshwater with only six marine species (Howson & Picton, 1997). Three species are listed for the Plymouth area; one species Podon leuckartii (G.O.Sars) is described as rare (M.B.A., 1957).
2. Acorn and goose barnacles (Cirripedia: Thoracica)Howson & Picton (1997) list 32 acorn and goose barnacles, 27 of which have been recorded in Cornish waters. These include the exotic barnacles Conchoderma auritum (Linnaeus) and C. virgatum (Spengler) which are occasionally encountered on whales and floating objects as well as Stomatolepas elegans (Costa), which lives on the carapace and flippers of the Leathery Turtle Dermochelys coriacea (Linnaeus).
Pollicipes pollicipes A Goose Barnacle
3. Parasitic barnacles ( Cirripedia: Rhizocephala)26 species are listed in this sub-group which are always endoparasitic on other crustaceans: detailed information is given in Hoeg & Lutzen (1985). About nine of these species have been recorded in Cornish waters.
4. Copepods (Copepoda)
About 1300 of the 1500 British species of Copepoda are marine; the rest live in freshwater with a few in damp soils. Many are free-living whilst others have adopted a commensal or parasitic mode of life. Useful reference works are by Kabata (1979; 1992).
4.1. Harpacticoida (in part)The Harpacticoida is one of 10 orders of the sub-class Copepoda. All the following information is from Huys et al. (1996) who set out to disprove the claim that the hundreds of British species of Harpacticoida “all look exactly the same” and “are absolutely impossible to identify”. There are approximately 900 “local” species i.e. those in north-west Europe. They are usually the second most abundant group of animals (after nematodes) in marine benthic communities. 160 species are known from the Isles of Scilly (Wells, 1970) but Dr. J.M. Gee (pers. comm.) has many additions which will be published in due course.
4.2. Siphonostomatoida and PoecilostomatoidaThe Copepods that parasitise fish (Siphonostomatoida and Poecilostomatoida) have been particularly well-studied in Cornwall, and the following list includes some of the more notable species. It is conceded that many are rare because they are frequently over-looked or because of the rarity of the hosts. Additional information on these parasitic copepods has been provided by Dr. Z. Kabata.
5. Bean animalcules ( Ostracoda)These are small crustaceans, encased in chitinous valves. They live in the sea and brackish water as well as freshwater. The following information comes from Athersuch et al. (1989), who list 116 species, of which 65 are recorded in the Plymouth area (M.B.A., 1957). Brady and Robertson (1874) recorded ca. 60 off the Isles of Scilly, including a few of the larger planktonic species which are dealt with by Angel (1993) but which are not considered here.
Two British species are recognised by Dahl (1985), one of which, Nebalia herbstii Leach, is common in the intertidal pools on St. Martin’s, Isles of Scilly, (Bamber, 2008) and is not regarded as a RDB species. The other is a more northerly species possibly found in the Shetland Isles.
Nebalia bipes (O.Fabricius), as detailed by Mauchline (1984) and noted in the 1996 Red Data Book, is no longer accepted as a British species (Dahl, 1985; Walker-Smith & Poore, 2001.) Thus, without voucher specimens, the Nebalia bipes records held on the ERICA database can not be re-assigned.
7. Mantis shrimps (Stomatopoda)
8. Opossum shrimps (Mysidacea)None are more than 3cm long. The coastal species treated by Makings (1977) occur down to 20m, some forming dense swarms in estuaries, where they are an important part of food chains. They are less common intertidally. There are 29 British species (Makings, 1977), of which 28 have been found in the Plymouth area (M.B.A., 1957).
9. Sand-hoppers etc. (Amphipoda: Gammaridea)This is the largest group of the amphipods with freshwater and land representatives as well as the 269 marine species listed by Lincoln (1979) from whom the habitat and distribution notes are taken: the listed species are, with two exceptions, from his list of warm-temperate species which he defines as “those species which penetrate northwards along the Atlantic coast of Europe and reach the south-western coasts of Britain, and south and west Ireland”. Those that extend as far as north as Liverpool Bay and as far east as the Wash have been omitted.
10. Skeleton shrimps and whale lice ( Amphipoda: Caprellidea)Apart from the whale lice which occasionally occur, there are about 12 species of skeleton shrimps listed by Hayward & Ryland (1990). All are marine, living amongst hydroids and algae, often on buoys, and may be found in the shallow sublittoral or even to much greater depths.
Caprella andreae A ghost shrimp
11. Amphipoda: Hyperiidea
Howson & Picton (1997) list eight species, three of which are found in the Plymouth area. One of these, Hyperia medusarum (Müller) is “... on extreme S.W. limit of its range” (M.B.A., 1957).
12. Marine slaters, gribbles and fish lice ( Isopoda)The isopods, apart from the parasitic species, are similar in form to the terrestrial and freshwater woodlice and waterlice. There are “at least 85 species” (Crothers, 1997); 48 of these (including Ligia oceanica) are known in the Plymouth area (M.B.A., 1957) and 52 are listed on the ERICA database. The main distribution notes are from Naylor (1972). The terrestrial isopods are treated separately.
Tanaids are small elongate crustaceans living in burrows, tubes, crevices or under stones in soft sand or muddy substrates. There are some 30 shallow water species around the British Isles with far more at 200m depth and at least six species are widely reported from south-western coasts (Hayward & Ryland, 1990). Holdich & Jones (1983) list 28 British species, 10 of which were recorded in the Plymouth area in the early 1900s (M.B.A., 1957). The whole group is thought to be somewhat under-recorded.
N.B. The genus Leptochelia is undergoing major revision and current Cornish records of L. dubia and L. savigny are likely to be re-assigned (Bamber, 2008).
14. CumaceaThe Cumacea are unspectacular small animals that mostly live in mud; there are 41 British species (Jones, 1976), of which 13 have been recorded in the Cornish region. Only one of these is considered to be nationally scarce.
These small shrimp-like crustaceans are strictly marine, never being found even in brackish water, and they vary in size from 13 to 55mm. There are 16 European species (Mauchline, 1984), most of which have a wide range northwards. Nyctiphanes couchi (Bell), which is not generally found north of the Shetlands, was taken from Mackerel Scomber scombrus taken south of The Lizard and named after Dr Jonathan Couch. There are seven British species (Mauchline, 1984; Crothers, 1997), of which three have been recorded in the Plymouth area (M.B.A., 1957).
16. Crabs, prawns, shrimps & lobsters ( Decapoda)
16.1. Prawns & shrimps
Alpheus macrocheles Snapping Prawn
16.2. Crawfish, lobsters, squat lobsters and Anomuran crabs
Galathea nexa Embleton’s Galatheid
Lithodes maja Northern Stone Crab
Palinurus mauritanicus Moroccan Crawfish
Palinurus elephas Common Crawfish or Spiny Lobster
Scyllarus arctus The Sand or Shovel-nosed Lobster
16.3. Hermit crabs
Pagurus forbesii Rough-clawed Hermit Crab
16.4. CrabsThe crabs are probably the most well-known of the crustaceans, with 60-70 British species (Clark, 1986); about 45 of which have been recorded from the coasts of Cornwall and the Isles of Scilly. The American Lobster Homarus americanus is occasionally caught in Cornish waters, but has not been included here because individuals may have been transported across the Atlantic as larval stages in the ballast of tankers or escaped from culture cages on the Breton coast.
Achaeus cranchii Cranch’s Spider Crab
Dromia longipes Sponge or Sleepy Crab
Eriphia verrucosa Warty/Yellow Crab
Liocarcinus arcuatus Arch-fronted Swimming Crab
Liocarcinus corrugatus Wrinkled Swimming Crab
Monodaeus couchi Couch’s Crab
Nepinnotheres pinnotheres Pinna or Ancient Pea Crab
Paromola cuvieri Box Crab
Pisa armata Gibb’s Spider Crab
Planes minutus Gulfweed or Columbus’ Crab
Polybius henslowii Nipper or Henslow’s Swimming Crab
Thia scutellata Polished or Thumb-nail Crab