Crab

Crab Temporal range: Early Jurassic–Present PreꞒ Ꞓ O S D C P T J K Pg N
Top row, left to right: Dromia personata (Dromiidae), Dungeness crab (Cancridae), Tasmanian giant crab (Menippidae); Middle row: Corystes cassivelaunus (Corystidae), Liocarcinus vernalis (Portunidae), Carpilius maculatus (Carpiliidae); Bottom row: Gecarcinus quadratus (Gecarcinidae), Grapsus grapsus (Grapsidae), Ocypode ceratophthalmus (Ocypodidae).
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
(unranked):	Reptantia
Infraorder:	Brachyura Linnaeus, 1758
Sections and subsections[1]
Dromiacea Raninoida Cyclodorippoida Eubrachyura Heterotremata Thoracotremata

Crabs are

Crabs vary in size from the pea crab, a few millimeters wide, to the Japanese spider crab, with a leg span up to 4 m (13 ft).^[6] Several other groups of crustaceans with similar appearances – such as king crabs and porcelain crabs – are not true crabs, but have evolved features similar to true crabs through a process known as carcinisation.^{[7][8][9][10]}

Environment

Crabs are found in all of the world's oceans, as well as in

Crabs often show marked

Reproduction and life cycle

Crabs attract a mate through chemical (

When development is complete, the female releases the newly hatched

Each species has a particular number of zoeal stages, separated by

Most species of terrestrial crabs must migrate down to the ocean to release their larvae; in some cases, this entails very extensive migrations. After living for a short time as larvae in the ocean, the juveniles must do this migration in reverse. In many tropical areas with land crabs, these migrations often result in considerable roadkill of migrating crabs.^{[17]: 113–114}

Once crabs have become juveniles, they still have to keep moulting many more times to become adults. They are covered with a hard shell, which would otherwise prevent growth. The moult cycle is coordinated by

Crabs typically walk sideways^[18] (hence the term crabwise), because of the articulation of the legs which makes a sidelong gait more efficient.^[19] Some crabs walk forward or backward, including raninids,^[20] Libinia emarginata^[21] and Mictyris platycheles.^[18] Some crabs, like the Portunidae and Matutidae, are also capable of swimming,^[22] the Portunidae especially so as their last pair of walking legs are flattened into swimming paddles.^[17]: 96

Crabs are mostly active animals with complex behaviour patterns such as communicating by drumming or waving their

Crabs are known to work together to provide food and protection for their family, and during mating season to find a comfortable spot for the female to release her eggs.[28]

Human consumption

Fisheries

Crabs make up 20% of all marine

In some crab species, meat is harvested by manually twisting and pulling off one or both claws and returning the live crab to the water in the knowledge that the crab may survive and regenerate the claws.^[30][31][32]

Cookery

In some regions, spices improve the culinary experience. In Southeast Asia and the Indosphere, masala crab and chilli crab are examples of heavily spiced dishes. In the Chesapeake Bay region, blue crab is often steamed with Old Bay Seasoning. Alaskan king crab or snow crab legs are usually simply boiled and served with garlic or lemon butter.

For the British dish dressed crab, the crab meat is extracted and placed inside the hard shell. One American way to prepare crab meat is by extracting it and adding varying amounts of binders, such as egg white, cracker meal, mayonnaise, or mustard, creating a crab cake. Crabs can also be made into a bisque, a global dish of French origin which in its authentic form includes in the broth the pulverized shells of the shellfish from which it is made.

Imitation crab, also called surimi, is made from minced fish meat that is crafted and colored to resemble crab meat. While it is sometimes disdained among some elements of the culinary industry as an unacceptably low-quality substitute for real crab, this does not hinder its popularity, especially as a sushi ingredient in Japan and South Korea, and in home cooking, where cost is often a chief concern.^[33] Indeed, surimi is an important source of protein in most East and Southeast Asian cultures, appearing in staple ingredients such as fish balls and fish cake.

Pain

Whether crustaceans as a whole experience pain or not is a scientific debate that has ethical implications for crab dish preparation. Crabs are very often boiled alive as part of the cooking process.

Evolution

The earliest unambiguous crab

Brachyura is separated into several sections, with the basal Dromiacea diverging the earliest in the evolutionary history, around the Late Triassic or Early Jurassic. The group consisting of Raninoida and Cyclodorippoida split off next, during the Jurassic period. The remaining clade Eubrachyura then divided during the Cretaceous period into Heterotremata and Thoracotremata. A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: ^{[42] [41]}

There is a no consensus on the relationships of the subsequent

Numbers of extant and extinct (†) species are given in brackets.[1] The superfamily Eocarcinoidea, containing Eocarcinus and Platykotta, was formerly thought to contain the oldest crabs; it is now considered part of the Anomura.^[45]

Examples of different crab sections

Ocypode quadrata (Thoracotremata: Ocypodidae)

Goneplax rhomboides

• Section †
  Callichimaeroida
  • †
    Callichimaeroidea (1†)^[46]
• Section Dromiacea
  • †Dakoticancroidea (6†)
  • Dromioidea (147, 85†)
  • Glaessneropsoidea (45†)
  • Homolodromioidea
    (24, 107†)
  • Homoloidea (73, 49†)
• Section Raninoida (46, 196†)
• Section Cyclodorippoida (99, 27†)
• Section Eubrachyura
  • Subsection Heterotremata
    • Aethroidea
      (37, 44†)
    • Bellioidea
      (7)
    • Bythograeoidea
      (14)
    • Calappoidea (101, 71†)
    • Cancroidea (57, 81†)
    • Carpilioidea (4, 104†)
    • Cheiragonoidea
      (3, 13†)
    • Corystoidea
      (10, 5†)
    • †
      Componocancroidea
      (1†)
    • Dairoidea (4, 8†)
    • Dorippoidea (101, 73†)
    • Eriphioidea (67, 14†)
    • Gecarcinucoidea (349)
    • Goneplacoidea (182, 94†)
    • Hexapodoidea
      (21, 25†)
    • Leucosioidea (488, 113†)
    • Majoidea (980, 89†)
    • Orithyioidea
      (1)
    • Palicoidea (63, 6†)
    • Parthenopoidea
      (144, 36†)
    • Pilumnoidea (405, 47†)
    • Portunoidea (455, 200†)
    • Potamoidea (662, 8†)
    • Pseudothelphusoidea
      (276)
    • Pseudozioidea (22, 6†)
    • Retroplumoidea
      (10, 27†)
    • Trapezioidea (58, 10†)
    • Trichodactyloidea
      (50)
    • Xanthoidea (736, 134†) ^[47]
  • Subsection Thoracotremata ^[48]
    • Cryptochiroidea
      (46)
    • Grapsoidea (493, 28†)
    • Ocypodoidea (304, 14†)
    • Pinnotheroidea
      (304, 13†)

Recent studies have found the following

• The Thoracotremata superfamily Grapsoidea is polyphyletic
• The Thoracotremata superfamily Ocypodoidea is polyphyletic
• The Heterotremata superfamily Calappoidea is polyphyletic
• The Heterotremata superfamily Eriphioidea is polyphyletic
• The Heterotremata superfamily Goneplacoidea is polyphyletic
• The Heterotremata superfamily Potamoidea is paraphyletic with respect to Gecarcinucoidea, which is resolved by placing Gecarcinucidae within Potamoidea
• The Majoidea families Epialtidae, Mithracidae and Majidae are polyphyletic with respect to each other
• The Dromioidea family Dromiidae may be paraphyletic with respect to Dynomenidae
• The Homoloidea family Homolidae is paraphyletic with respect to Latreilliidae
• The Xanthoidea family Xanthidae is paraphyletic with respect to Panopeidae

Cultural influences

Both the

The Kapsiki people of North Cameroon use the way crabs handle objects for divination.^{[citation needed]}

The term crab mentality is derived from a type of detrimental social behavior observed in crabs.

Explanatory notes

References