Cancer (genus)
For other uses, see Cancer.
Cancer is a genus of marine crabs in the family Cancridae. It includes eight extant species and three extinct species, including familiar crabs of the littoral zone, such as the European edible crab, the Jonah crab and the red rock crab. It is thought to have evolved from related genera in the Pacific Ocean in the Miocene.
Description
The species placed in the genus Cancer are united by the presence of a single posterolateral spine, anterolateral spines with deep fissures, and a short extension of the carapace forward between the eyes. Their claws are typically short, with grainy or smooth, rather than spiny, keels. The carapace is typically oval, being 58%–66% as long as wide, and the eyes separated by 22%–29% of the carapace width.Species
The genus Cancer, as currently circumscribed, contains eight extant species:Image | Name | Common name | Distribution |
Cancer bellianus Johnson, 1861 | toothed rock crab | north-eastern Atlantic Ocean. | |
Cancer borealis Stimpson, 1859 | Jonah crab | east coast of North America from Newfoundland to Florida. | |
Cancer irroratus Say, 1817 | Atlantic rock crab | from Iceland to [South Carolina | |
Cancer johngarthi Carvacho, 1989 | eastern Pacific Ocean from Mexico to Panama | ||
Cancer pagurus Linnaeus, 1758 | edible crab or brown crab | the North Sea, North Atlantic Ocean, and perhaps the Mediterranean Sea. | |
Cancer plebejus Poeppig, 1836 | Chilean crab | Southeast Pacific and Southwest Atlantic: Chile and Peru. | |
Cancer porteri Rathbun, 1930 | |||
Cancer productus J. W. Randall, 1840 | red rock crab | Kodiak Island, Alaska to Isla San Martine, Baja California |
Three fossil species are also included:
- Cancer fissus Rathbun, 1908 – Pliocene, California
- Cancer fujinaensis Sakumoto, Karasawa & Takayasu, 1992 – Miocene, Japan
- Cancer parvidens Collins & Fraaye, 1991 – Miocene, Netherlands
Taxonomic history
When zoological nomenclature was first standardised by Carl Linnaeus in the 1758 10th edition of Systema Naturae, the genus Cancer included almost all crustaceans, including all the crabs. Linnaeus' cumbersome genus was soon divided into more meaningful units, and Cancer had been restricted to one group of true crabs by the time of Pierre André Latreille's 1802 work Histoire naturelle, générale et particulière des Crustacés et des Insectes. Latreille designated C. pagurus to be the type species in 1817.In 1975, J. Dale Nations divided the genus Cancer into four subgenera: Cancer , Cancer , Cancer and Cancer . Each of these is now treated as a separate genus, as is the genus Platepistoma, erected by Mary J. Rathbun and resurrected in 1991. Since that time, further genera have been described to accommodate species previously included in Cancer, and the genus Cancer now contains only eight extant species.