Edible crabs

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Edible crabs
Pocket crab (Cancer pagurus)

Pocket crab ( Cancer pagurus )

Systematics
Class : Higher crabs (Malacostraca)
Order : Decapods (decapoda)
Subordination : Pleocyemata
Partial order : Crab (Brachyura)
Superfamily : Cancroidea
Family : Edible crabs
Scientific name
Cancridae
Latreille , 1802
Metacarcinus gracilis
Fossil of Lobocarcinus sismondai from the Oligocene

The crabs or rock crab (Cancridae) form a family of crabs . It consists of six recent and eleven extinct genera and is taxonomically divided into two subfamilies (Cancrinae and † Lobocarcininae). Its best-known representative is the eponymous pocket crab ( Cancer pagurus ). Until the revision by Schweitzer and Feldmann, all living (recent) species were often placed in the single genus Cancer . There are 24 known species. Some species are intensively fished and are of high commercial importance.

features

Cancridae are extremely variable in size from small forms such as Glebocarcinus oregonensis (carapace width up to 27 millimeters, up to about 5 grams of body weight) to forms such as the crab (up to 184 millimeters carapace width and about 330 grams of body weight) and Cancer magister (up to 230 millimeters Carapace width). The wide, oval or hexagonal carapace is typical of the family . It has 5 small teeth between the eye sockets (for fossils: 4 to 6) and on its front lateral edge more than 8 teeth separated by crevices. The individual regions of the carapace can be distinct to very indistinct. The surface texture of the carapace also ranges from coarse-grained to completely smooth. The sternum is typically narrow, in males sternites 3 to 5 are often fused. The first antenna (antennae) is folded lengthways. The basal part of the second antenna is longer than it is wide, the distal section (flagellum) short and more or less hairy. The scissor fingers are curved and have quills that can carry small thorns or grains. They are very different in shape from short and curved to long and slender. The last pairs of legs (peraeopods) are different depending on the species, but are never designed as swimming legs.

development

Male edible crabs look for females, who then defend them against other males. They are likely to be attracted by a pheromone given off by the female . The mating occurs immediately after the female has molted when the carapace has not yet hardened. Cancridae eggs have a diameter of about 300 to 500 micrometers, which is independent of the size of the adult. The number of eggs, on the other hand, depends very much on body size, which varies between almost 20,000 in the small Glebocarcinus oregonensis to over two and a half million in the case of pocket cancer. As is typical for crabs, the eggs are glued to the pleopods and carried around. Usually they are put down before hatching, often in a self-dug cavity. After a protozoal stage that has only lived for a few minutes, all species develop into young crabs via five free-swimming Zoea larvae, which pass through in about 30 to 60 days, and one megalopa larva. Most species then go through 9 to 11 stages until sexually mature, for which they need one to two years (the small Glebocarcinus oregonensis takes half a year). A maximum lifespan of eight years is given for the large species.

ecology

Cancridae are ground-living ( benthic ) species that occur from the tidal tidal flats to medium depths (around 900 meters). They live on substrates of all kinds, from rocks to sand and silt. They are considered to be omnivorous. Most of the species' main prey are molluscs and other crustaceans. Cannibalism occurs both outdoors and when kept.

distribution

Cancridae live in cold (boreal) to warm-temperate marine areas. No species is found in arctic waters. In warm seas, a water temperature of 24 ° C appears to mark the upper limit for occurrence. There is only one species in the Gulf of Mexico, and here only on the west coast of Florida. On the Pacific coast they come to the California Peninsula, and then again along the coast of South America to the Strait of Magellan.

The genera Anatolikos and Glebocarcinus are endemic to the North Pacific . Cancer s. s. and Metacarcinus occur in the entire North Pacific to the Southeast Pacific and the North Atlantic , one species of Metacarcinus is found in New Zealand . Romaleon occurs in the Circum-North Pacific region, one species is widespread as far as the southeastern Pacific region. The genus Platepistoma is only known from the Indo-Pacific .

use

For the use of the edible crab cf. there. The most important species used in America is Cancer magister with an annual catch of around 16 million kilograms with a commercial value of around 5.5 million dollars. The other Pacific species are used by recreational fishermen and their catch does not account for more than 1% of the total catch.

Fossil species

Fossil Cancridae have been documented since the middle Eocene . The primary distribution area of ​​† Lobocarcininae was the Tethys Sea , all but one species are known from this region.

Internal system

The edible crab family is divided into two subfamilies, which can be differentiated between the eye sockets based on their teeth. Those of the extinct Lobocarcininae always have an even number, while the Cancrinae have five. The following genera of edible crabs have been described so far:

Cancrinae Latreille subfamily , 1802

Subfamily † Lobocarcininae Beurlen , 1930

swell

  • Peter KL Ng, Danièle Guinot & Peter JF Davie (2008). Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world. In: Raffles Bulletin of Zoology 17: 1-286. ( Online ; PDF; 8.2 MB)
  • Sammy De Grave, N. Dean Pentcheff, Shane T. Ahyong, et al. (2009). A classification of living and fossil genera of decapod crustaceans. In: Raffles Bulletin of Zoology Suppl. 21: 1-109. ( Online ; PDF; 8.1 MB)

Individual evidence

  1. ↑ a b c d e Carrie E. Schweitzer, Rodney M. Feldmann: Re-evaluation of the Cancridae Latreille, 1802 (Decapoda: Brachyura) including three new genera and three new species. In: Contributions to Zoology , 69 (4), 2000 ( Online ( Memento of the original from December 9, 2012 in the web archive archive.today ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to instructions and then remove this notice. ) @1@ 2Template: Webachiv / IABot / dpc.uba.uva.nl
  2. ↑ a b Anson H. Hines (1991): Fecundity and Reproductive Output in Nine Species of Cancer crabs (Crustacea, Brachyura, Cancridae). Canadian Journal of Fisheries and Aquatic Sciences Vol. 48: 267-275.
  3. ↑ Marine Species Identification Portal: Family Cancridae
  4. ^ John H. Christy (1987): Competitive mating, mate choice and mating associations of Brachyuran crabs. Bulletin of Marine Science 41 (2): 177-191.
  5. ↑ Rodolfo Quintana & Hugo Saelzer (1986): The Complete Larval Development of the Edible Crab, Cancer setosus Molina and Observations on the Prezoeal and First Zoeal Stages of C. coronatus Molina (Decapoda: Brachyura, Cancridae). Journal of the Faculty of science Hokkaido University Series 6. Zoology 24 (4): 267-303.
  6. ↑ Jeffrey D. Shields (1991): The reproductive ecology and fecundity of Cancer crabs. In: AM Wenner & AM Kuris (editors) Crustacean Egg Production. Crustacean Issues Vol 7: 193-213.
  7. ↑ Gerardo Cerda & Matthias Wolff (1993): Feeding ecology of the crab Cancer polyodon in La Herradura Bay, northern Chile. 11. Food spectrum and price consumption. Marine ecology progress series Vol. 100: 119-125.
  8. ↑ BI Sirenko (editor): Illustrated Keys to Free-Living Invertebrates of Eurasian Arctic Seas and Adjacent Deep Waters. Volume 1: Rotifera, Pycnogonida, Cirripedia, Leptostraca, Mysidacea, Hyperiidea, Caprellidea, Euphausiacea, Natantia, Anomura, and Brachyura. Published by Alaska Sea Grant College Program. University of Alaska Fairbanks. Fairbanks, Alaska, USA.
  9. ↑ Lawrence W. Powers (1977): A Catalog and Bibliography to the Crabs (Brachyura) of the Gulf of Mexico. Contributions in Marine Science. Supplement to Volume 20.
  10. ^ John S. Garth & Donald P. Abbott (1980): Brachyura: The true crabs . In: Robert Hugh Morris, Donald Putnam Abbott, Eugene Clinton Haderlie (Eds.): Intertidal invertebrates of California . Stanford, California; Stanford University Press. Pp. 594–630, here p. 605.
  11. ↑ Peter JF Davie & Peter KL Ng (2012): A new species of Platepistoma Rathbun, 1906 (Decapoda: Brachyura: Cancridae) from deep water off South Africa. Zootaxa 3522: 73-80.

Web links

Commons : Edible Crabs (Cancridae)  - Collection of images, videos and audio files