Metacarcinus gracilis

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Metacarcinus gracilis
Cancergracilis.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Brachyura
Family: Cancridae
Genus: Metacarcinus
Species:
M. gracilis
Binomial name
Metacarcinus gracilis
(Dana, 1852)  [1]
Synonyms [1]

Cancer gracilisDana, 1852

The graceful rock crab or slender crab, Metacarcinus gracilis (the naming convention recognized by WoRMS) or Cancer gracilis (the naming convention recognized by ITIS), is one of only two members of the genus Metacarcinus, recognized by WoRMS, whose chelae (claws) are white tipped, the other crab being M. magister (Dungeness crab). [2] Both of these eastern Pacific crab species are recognized by ITIS as belonging to the much larger genus Cancer. M. gracilis has been caught from Alaska to Bahía Magdelena, Baja California. [3] Although M. gracilis is only found in the Pacific Ocean, it has cousins in the Atlantic Ocean. The genus Cancer ( sensu lato ) apparently evolved in the Pacific Ocean and later migrated to the Atlantic Ocean. [4] Larvae and small juveniles of this species are often seen riding jellyfish, especially Phacellophora camtschatica . The juvenile crabs steal food from the jellyfish and also clean off parasitic amphipods. [5]

Morphology

Like the other members of the family Cancridae, the slender crab has a very broad and oval carapace with dull, tooth-like protrusions toward the front of the carapace. Female crabs can be distinguished from males by a broad tail flap on their undersides, which are used for protecting their eggs when they are gravid. The slender crab carapace is usually olive brown, and its legs vary from yellowish brown to purple. M. gracilis only grows to a width of about 3.5 inches (9 cm) and resembles a juvenile M. magister . Often the two species can be confused, as M. gracilis looks very similar to a juvenile Dungeness crab. They can readily be distinguished from each other, though M. gracilis has a notch behind the widest point of its carapace that M. magister lacks, and the top joint of its pincers are not serrated like those of M. magister. More obscure ways to tell are by the appearance of hair on the posterior three legs of M. magister where M. gracilis is almost always hairless. Another telling characteristic of the slender crab is that the last segment of its tail flap is pointed, where M. magister is curved.

Related Research Articles

Dungeness crab species of crustacean

The Dungeness crab, Metacarcinus magister or Cancer magister, is a species of crab that inhabits eelgrass beds and water bottoms on the west coast of North America. It typically grows to 20 cm (7.9 in) across the carapace and is a popular seafood. Its common name comes from the port of Dungeness, Washington, United States, where it is "a prized crustacean that supports the most valuable fishery on the west coast", and where ocean acidification threatens the marine environment.

<i>Cancer</i> (genus) Genus of crabs

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.

<i>Phacellophora camtschatica</i> Species of jellyfish

Phacellophora camtschatica, commonly known as the fried egg jellyfish or egg-yolk jellyfish, is a very large jellyfish in the family Phacellophoridae. This species can be easily identified by the yellow coloration in the center of its body which closely resembles an egg yolk, hence how it got its common name. Some individuals can have a bell close to 60 cm (2 ft) in diameter, and most individuals have 16 clusters of up to a few dozen tentacles, each up to 6 m (20 ft) long. A smaller jellyfish, Cotylorhiza tuberculata, typically found in warmer water, particularly in the Mediterranean Sea, is also popularly called a fried egg jellyfish. Also, P. camtschatica is sometimes confused with the Lion's mane jellyfish.

<i>Leptograpsus</i> Genus of crabs

Leptograpsus variegatus, known as the purple rock crab, is a marine large-eyed crab of the family Grapsidae, found in southern subtropical Indo-Pacific Oceans. It grows to around 50 millimetres (2.0 in) shell width. It is the only species in the genus Leptograpsus.

<i>Cancer productus</i> Species of crab

Cancer productus, one of several species known as red rock crabs, is a crab of the genus Cancer found on the western coast of North America.

<i>Metacarcinus</i> Genus of crabs

Metacarcinus is a genus of crabs formerly included in the genus Cancer. It includes nine exclusively fossil species and five extant species, of which four are also known from the fossil record. The monophyly of this genus was not supported by a molecular study using the cytochrome oxidase I gene.

<i>Oregonia</i> (genus) Genus of crabs

Oregonia is a genus of crabs, comprising two extant species and one fossil species: It is classified in the family Oregoniidae under the spider crab superfamily Majoidea.

<i>Libinia dubia</i> Species of crab

Libinia dubia, the longnose spider crab, is a species of crab in the family Epialtidae. It is found in shallow waters on the eastern coast of North America.

Libinia ferreirae is a species of tropical spider crab in the family Epialtidae. It is found on the seabed in shallow waters off the Atlantic coast of South America.

<i>Carpilius maculatus</i> Species of crab

Carpilius maculatus common names seven-eleven crab, spotted reef crab, dark-finger coral crab, and large spotted crab, is a species of crab in the family Carpiliidae, which also includes C. convexus and C. corallinus. While there have reports of the C. maculatus as being poisonous, biochemical testing has revealed that they lack any paralytic shellfish toxins.

<i>Oregonia bifurca</i> Species of crab

Oregonia bifurca, commonly known as the split-nose crab or the split-nose decorator crab, is a species of crabs belonging to the genus Oregonia. It is a rare deep-water species that inhabits the tops of seamounts and guyots in the northeastern Pacific Ocean; from the Aleutian Islands, the Bering Sea, the Hawaiian–Emperor seamount chain, to the waters off British Columbia. It is closely related to the more common shallow-water species Oregonia gracilis, the graceful decorator crab.

<i>Neohelice</i> Genus of crabs

Neohelice granulata is a species of crab in the family Varunidae, and the only species in the genus Neohelice. In 2009, it was estimated that N. granulata was the sixth most studied species of crab.

Alepas pacifica is a species of goose barnacle in the family Heteralepadidae. It is a pelagic species and is an obligate associate of various species of jellyfish. It mainly occurs in the Pacific Ocean.

<i>Phalangipus longipes</i> Species of crab

Phalangipus longipes is a species of crabs in the family Epialtidae.

<i>Myra fugax</i> Species of crab

Myra fugax is a species of crabs in the family Leucosiidae.

<i>Metacarcinus edwardsii</i> Species of crab

Metacarcinus edwardsii, sometimes known as mola rock crab, southern rock crab, or Chilean rock crab, is a species of crab from the Pacific coast of South America.

<i>Heterosaccus</i> Genus of barnacles

Heterosaccus is a genus of barnacles in superorder Rhizocephala. Like other taxa in this superorder, they parasitize crabs. Geoffroy Smith circumscribed the genus in 1906; he initially only included H. hians. Smith circumscribed a genus distinct from Sacculina due to a difference of the mesentery; in Heterosaccus, the mesentery does not stretch down to the mantle opening but rather only is present on the ring of attachment.

Carcinonemertes errans is a ribbon worm in the family Carcinonemertidae. It lives in symbiosis with the Dungeness crab, consuming the crab's developing eggs. In 1980 it was implicated in the collapse of the Dungeness crab fishery in central California.

Calyptraeotheres garthi is a species of pea crab in the family Pinnotheridae. It is found in the southwestern Atlantic Ocean and is a parasitic castrator of the slipper limpet Crepidula cachimilla.

References

  1. 1 2 P. K. L. Ng; D. Guinot; P. J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology . 17: 1–286. Archived from the original (PDF) on 2011-06-06.CS1 maint: discouraged parameter (link)
  2. Eugene N. Kozloff (1983). Seashore Life of the Northern Pacific Coast. Seattle: University of Washington Press. ISBN   9780295960845.
  3. J. Dale Nations (1975). "The genus Cancer (Crustacea: Bachyura): systematics, biogeography, and fossil record" (PDF). Natural History Museum of Los Angeles County Science Bulletin. 23: 1–104.
  4. Michelle K. Harrison; Bernard J. Crespi (1999). "Phylogenetics of Cancer crabs (Crustacea: Decapoda: Brachyura)" (PDF). Molecular Phylogenetics and Evolution . 12 (2): 186–199. doi:10.1006/mpev.1998.0608. PMID   10381321.
  5. Trisha Towanda; Erik V. Thuesen (2006). "Ectosymbiotic behavior of Cancer gracilis and its trophic relationships with its host Phacellophora camtschatica and the parasitoid Hyperia medusarum". Marine Ecology Progress Series . 315: 221–236. Bibcode:2006MEPS..315..221T. doi: 10.3354/meps315221 .