Cancer (genus)
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Cancer Temporal range: Miocene–Recent |
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| Edible crab, Cancer pagurus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Crustacea |
| Order: | Decapoda |
| Infraorder: | Brachyura |
| Family: | Cancridae |
| Genus: |
Cancer Linnaeus, 1758 |
| Type species | |
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Cancer pagurus Linnaeus, 1758 |
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| Synonyms | |
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Platycarcinus H. Milne-Edwards, 1834 |
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Platycarcinus H. Milne-Edwards, 1834
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 (Cancer pagurus), the Jonah crab (Cancer borealis) and the red rock crab (Cancer productus). It is thought to have evolved from related genera in the Pacific Ocean in the Miocene.
The species placed in the genus Cancer are united by the presence of a single posterolateral spine (on the edge of the carapace, towards the rear), anterolateral spines with deep fissures (on the carapace edge, towards the front), 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.
The genus Cancer, as currently circumscribed, contains eight extant species:
Three fossil species are also included:
As their generic delimitation was based on characters of the dorsal carapace, Schweitzer and Feldmann (2000) were unable to confirm the placement of Cancer tomowoi in the genus, since it is known only from parts of the sternum and the legs. Other species until recently included in the genus Cancer have since been transferred to other genera, such as Glebocarcinus, Metacarcinus and Romaleon.
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 ("Natural history in general, and specifically that of crustaceans and insects"). Latreille designated C. pagurus to be the type species in 1817.
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