Crabs are
decapod crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s of the
infraorder Brachyura, which typically have a very short projecting "
tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
" (
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
) ( el,
βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the c ...
. They live in all the world's oceans, in
freshwater, and on
land, are generally covered with a thick exoskeleton, and have a single pair of pincers. They first appeared during the
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
Period.
Description
Crabs are generally covered with a thick
exoskeleton
An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...
, composed primarily of highly mineralized
chitin, and armed with a pair of
chelae
A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...
(claws). Crabs vary in size from the
pea crab, a few millimeters wide, to the
Japanese spider crab, with a leg span up to . 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.
Environment
Crabs are found in all of the world's oceans, as well as in
fresh water and on
land, particularly in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
regions. About 850
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...
are
freshwater crabs.
Sexual dimorphism
Crabs often show marked
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
. Males often have larger
claws, a tendency that is particularly pronounced in the
fiddler crab
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, whil ...
s of the genus ''Uca'' (
Ocypodidae
The Ocypodidae are a family of semiterrestrial crabs that includes the ghost crabs and fiddler crabs. They are found on tropical and temperate shorelines around the world.
Some genera previously included in the family are now treated as members ...
). In fiddler crabs, males have one greatly enlarged claw used for communication, particularly for attracting a mate. Another conspicuous difference is the form of the pleon (
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
); in most male crabs, this is narrow and triangular in form, while females have a broader, rounded abdomen. This is because female crabs brood fertilised eggs on their
pleopods.
Reproduction and lifecycle
Crabs attract a mate through chemical (
pheromones), visual, acoustic, or vibratory means. Pheromones are used by most fully aquatic crabs, while
terrestrial and semiterrestrial crabs often use visual signals, such as
fiddler crab
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, whil ...
males waving their large claws to attract females. The vast number of brachyuran crabs have
internal fertilisation and mate belly-to-belly. For many aquatic species, mating takes place just after the female has moulted and is still soft. Females can store the
sperm for a long time before using it to fertilise their
eggs. When fertilisation has taken place, the eggs are released onto the female's abdomen, below the tail flap, secured with a sticky material. In this location, they are protected during embryonic development. Females carrying eggs are called "berried" since the eggs resemble round berries.
When development is complete, the female releases the newly hatched
larvae into the water, where they are part of the
plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
. The release is often timed with the
tidal and light/dark diel cycle. The free-swimming tiny
zoea larvae can float and take advantage of water currents. They have a spine, which probably reduces the rate of predation by larger animals. The zoea of most species must find food, but some crabs provide enough
yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example ...
in the eggs that the larval stages can continue to live off the yolk.
Each species has a particular number of zoeal stages, separated by
moults, before they change into a
megalopa stage, which resembles an adult crab, except for having the abdomen (tail) sticking out behind. After one more moult, the crab is a
juvenile, living on the bottom rather than floating in the water. This last moult, from megalopa to juvenile, is critical, and it must take place in a habitat that is suitable for the juvenile to survive.
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.
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
hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
s. When preparing for moult, the old shell is softened and partly eroded away, while the rudimentary beginnings of a new shell form under it. At the time of moulting, the crab takes in a lot of water to expand and crack open the old shell at a line of weakness along the back edge of the
carapace
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
. The crab must then extract all of itself – including its legs,
mouthparts
Mouthparts may refer to:
* The parts of a mouth
** Arthropod mouthparts
The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired append ...
,
eyestalks, and even the lining of the front and back of the digestive tract – from the old shell. This is a difficult process that takes many hours, and if a crab gets stuck, it will die. After freeing itself from the old shell (now called an
exuvia), the crab is extremely soft and hides until its new shell has hardened. While the new shell is still soft, the crab can expand it to make room for future growth.
Behaviour
Crabs typically walk sideways
(a behaviour which spawned the term
crabwise), because of the articulation of the legs which makes a sidelong gait more efficient.
Some crabs walk forward or backward, including
raninids, ''
Libinia emarginata'' and ''
Mictyris platycheles
''Mictyris platycheles'' is a species of crab found on mudflats on the east coast of Australia from Tasmania and Victoria to Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Qu ...
''.
Some crabs, like the
Portunidae and
Matutidae
Matutidae is a family of crabs, sometimes called ''moon crabs'', adapted for swimming or digging. They differ from the swimming crabs of the family Portunidae in that all five pairs of legs are flattened, rather than just the last pair, as in Por ...
, are also capable of swimming,
the
Portunidae especially so as their last pair of walking legs are flattened into swimming paddles.
Crabs are mostly active animals with complex behaviour patterns such as communicating by drumming or waving their
pincers. Crabs tend to be aggressive toward one another, and males often fight to gain access to females. On rocky
seashores, where nearly all caves and crevices are occupied, crabs may also fight over hiding holes.
Fiddler crab
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, whil ...
s (genus ''Uca'') dig burrows in sand or mud, which they use for resting, hiding, and mating, and to defend against intruders.
Crabs are
omnivores, feeding primarily on
algae, and taking any other food, including
molluscs,
worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete wor ...
s, other
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s,
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...
,
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
, and
detritus, depending on their availability and the crab species. For many crabs, a mixed diet of plant and animal matter results in the fastest growth and greatest
fitness. Some species are more specialised in their diets, based in plankton, clams or fish.
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.
Human consumption
Fisheries
Crabs make up 20% of all marine
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s caught, farmed, and consumed worldwide, amounting to 1.5 million
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s annually. One species, ''
Portunus trituberculatus'', accounts for one-fifth of that total. Other commercially important
taxa include ''
Portunus pelagicus'', several species in the genus ''
Chionoecetes'', the blue crab (''
Callinectes sapidus''),
''Charybdis'' spp., ''
Cancer pagurus'', the
Dungeness crab
The Dungeness crab (''Metacarcinus magister'') is a species of crab inhabiting eelgrass beds and water bottoms along the west coast of North America. It typically grows to across the carapace and is a popular seafood. Its common name comes from ...
(''Metacarcinus magister''), and ''
Scylla serrata'', each of which yields more than 20,000 tonnes annually.
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.
Cookery
Crabs are prepared and eaten as a dish in many different ways all over the world. Some species are eaten whole, including the shell, such as
soft-shell crab; with other species, just the claws or legs are eaten. The latter is particularly common for larger crabs, such as the
snow crab. In many cultures, the
roe of the female crab is also eaten, which usually appears orange or yellow in fertile crabs. This is popular in Southeast Asian cultures, some Mediterranean and Northern European cultures, and on the East,
Chesapeake Chesapeake often refers to:
*Chesapeake people, a Native American tribe also known as the Chesepian
* The Chesapeake, a.k.a. Chesapeake Bay
*Delmarva Peninsula, also known as the Chesapeake Peninsula
Chesapeake may also refer to:
Populated plac ...
, and Gulf Coasts of the United States.
In some regions, spices improve the culinary experience. In
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland ...
and the
Indosphere
Indosphere is a term coined by the linguist James Matisoff for areas of Indian linguistic and cultural influence in South Asia and Southeast Asia. It is commonly used in areal linguistics in contrast with Sinosphere.
Influence
The Tibeto-B ...
,
masala
Masala, Massala or MASALA may refer to:
Spice
* Masala (spice), any of the many spice mixes used in South Asian cuisine
** Masala chai, a flavoured tea beverage
** Masala incense, Indian incense using a spice mix
** Masala dosa, an Indian dish
Pl ...
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 a paste made from fish or other meat. The term can also refer to a number of East Asian foods that use that paste as their primary ingredient. It is available in many shapes, forms, and textures, and is often used to mimic the texture and ...
, 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.
[Daniel P. Puzo (February 14, 1985]
Imitation Crab Draws Criticisms
''Los Angeles Times'' 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 often boiled alive as part of the cooking process.
Evolution
The earliest unambiguous crab
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s date from the
Early Jurassic, with the oldest being ''
Eocarcinus
''Eocarcinus praecursor'' is a Jurassic species of decapod crustacean, sufficiently distinct from its relatives to be placed in its own family (Eocarcinidae). Often considered the oldest true crab, it was considered by a 2010 study to be an ea ...
'' from the early
Pliensbachian of Britain, which likely represents a
stem-group lineage, as it lacks several key morphological features that define modern crabs. Most Jurassic crabs are only known from
dorsal (top half of the body)
carapaces, making it difficult to determine their relationships. Crabs
radiated in the
Late Jurassic, corresponding with an increase in reef habitats, though they would decline at the end of the Jurassic as the result of the decline of reef ecosystems. Crabs increased in diversity through the Cretaceous and represented the dominant group of
decapods by the end of the period.
The crab
infraorder Brachyura belongs to the group
Reptantia, which consists of the walking/crawling decapods (
lobsters
Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...
and crabs). Brachyura is the
sister clade
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to the infraorder
Anomura, which contains the hermit crabs and relatives. The
cladogram below shows Brachyura's placement within the larger
order
Order, ORDER or Orders may refer to:
* Categorization, the process in which ideas and objects are recognized, differentiated, and understood
* Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...
Decapoda, from analysis by Wolfe ''et al.'', 2019.
Brachyura is separated into several sections, with the
basal Dromiacea diverging the earliest in the evolutionary history, around the
Late Triassic
The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch ...
or
Early Jurassic. The group consisting of
Raninoida and
Cyclodorippoida split off next, during the
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
period. The remaining
clade Eubrachyura then divided during the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period into
Heterotremata and
Thoracotremata.
A summary of the high-level internal relationships within Brachyura can be shown in the
cladogram below:
There is a no consensus on the relationships of the subsequent
superfamilies and
families. The proposed
cladogram below is from analysis by Tsang ''et al'', 2014:
Classification
The
infraorder Brachyura contains approximately 7,000 species in 98
families,
as many as the remainder of the
Decapoda.
The evolution of crabs is characterised by an increasingly robust body, and a reduction in the
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
. Although many other groups have undergone similar processes,
carcinisation is most advanced in crabs. The
telson is no longer functional in crabs, and the
uropods are absent, having probably evolved into small devices for holding the reduced abdomen tight against the
sternum.
In most decapods, the
gonopores (sexual openings) are found on the legs. Since crabs use their first two pairs of
pleopods (abdominal appendages) for sperm transfer, this arrangement has changed. As the male abdomen evolved into a slimmer shape, the gonopores have moved toward the midline, away from the legs, and onto the sternum. A similar change occurred, independently, with the female gonopores. The movement of the female gonopore to the sternum defines the
clade Eubrachyura, and the later change in the position of the male gonopore defines the
Thoracotremata. It is still a subject of debate whether a
monophyletic group is formed by those crabs where the female, but not male, gonopores are situated on the sternum.
Superfamilies
Numbers of extant and extinct (†) species are given in brackets.
The superfamily
Eocarcinoidea, containing ''
Eocarcinus
''Eocarcinus praecursor'' is a Jurassic species of decapod crustacean, sufficiently distinct from its relatives to be placed in its own family (Eocarcinidae). Often considered the oldest true crab, it was considered by a 2010 study to be an ea ...
'' and ''
Platykotta
''Platykotta akaina'' is a species of decapod crustacean from the Triassic of the United Arab Emirates. It is the oldest known fossil from the infraorder Anomura, and is most closely related to '' Eocarcinus praecursor''.
Stratigraphy
The holo ...
'', was formerly thought to contain the oldest crabs; it is now considered part of the
Anomura.
* Section †
Callichimaeroida
''Callichimaera perplexa'' is a species of small crabs known from the Cretaceous Churuvita Group of Colombia and the Frontier Formation of the United States. Because it possesses a strange combination of anatomical features, it is said to be ...
** †
Callichimaeroidea
''Callichimaera perplexa'' is a species of small crabs known from the Cretaceous Churuvita Group of Colombia and the Frontier Formation of the United States. Because it possesses a strange combination of anatomical features, it is said to be ...
(1†)
* Section
Dromiacea
** †
Dakoticancroidea
Dakoticancroidea is a superfamily of fossil crabs, containing six species in five genera, divided into two families. The family Dakoticancridae is only known from North American rocks of Late Cretaceous age, while the single species in the Iber ...
(6†)
**
Dromioidea
Dromioidea is a superfamily of crabs mostly found in Madagascar. Dromioidea belongs the group Dromiacea, taxonomically ranked as a section, which is the most basal grouping of Brachyura crabs. Dromiacea likely diverged from the rest of Brac ...
(147, 85†)
**
Glaessneropsoidea
Glaessneropsoidea is a superfamily of fossil crabs. They are found in rocks from Late Jurassic age to Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geolog ...
(45†)
**
Homolodromioidea
Homolodromiidae is a family of crabs, the only family in the superfamily Homolodromioidea. In contrast to other crabs, including the closely related Homolidae, there is no strong ''linea homolica'' along which the exoskeleton breaks open during ...
(24, 107†)
**
Homoloidea
Homoloidea is a superfamily of dromiacean crabs. Homoloidea belongs the group Dromiacea, taxonomically ranked as a section, and is the sister group to Dromioidea. Dromiacea is the most basal grouping of Brachyura crabs, and likely diverged ...
(73, 49†)
* Section
Raninoida (46, 196†)
* Section
Cyclodorippoida (99, 27†)
* Section
Eubrachyura
** Subsection
Heterotremata
***
Aethroidea
The Aethridae are a family of crabs in their own superfamily, Aethroidea. It contains these genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the h ...
(37, 44†)
***
Bellioidea
Belliidae is a family of crabs of the order Decapoda
The Decapoda or decapods (literally "ten-footed") are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, shrimp and ...
(7)
***
Bythograeoidea
The Bythograeidae are a small family of blind crabs which live around hydrothermal vents. The family contains 16 species in six genera. Their relationships to other crabs are unclear. They are believed to eat bacteria and other vent organisms. B ...
(14)
***
Calappoidea
Calappoidea is a superfamily of crabs comprising the two families Calappidae and Matutidae. The earliest fossils attributable to the Calappoidea date from the Aptian
The Aptian is an age in the geologic timescale or a stage in the stratig ...
(101, 71†)
***
Cancroidea
Cancroidea is a superfamily of crabs, comprising the families Atelecyclidae and Cancridae. http://boletinsgm.igeolcu.unam.mx/bsgm/vols/epoca04/6502/%2810%29Osso.pdf Four other families have been separated into new superfamilies: Cheiragonidae ...
(57, 81†)
***
Carpilioidea
Carpilioidea is a superfamily of crabs containing a single extant family, Carpiliidae and three extinct families. The modern range of the family includes the Indo-Pacific, Western Atlantic and Caribbean Sea. The fossil record of the group exten ...
(4, 104†)
***
Cheiragonoidea
Cheiragonidae is a small family of crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden enti ...
(3, 13†)
***
Corystoidea
Corystidae is a family of crabs, in its own superfamily, Corystoidea. It includes what was once thought to be the oldest Eubrachyuran fossil, '' Hebertides jurassica'', thought to be dating from the Bathonian (Middle Jurassic); the species was s ...
(10, 5†)
*** †
Componocancroidea
''Componocancer roberti'' is an unusual species of fossil crab described in 2008. It lived in the Albian age (Early Cretaceous) in what is now Montana. The species is unlike any other described crab, and is therefore placed in its own family
...
(1†)
***
Dairoidea
Dairoidea is a superfamily of crabs, comprising two families which each contain a single genus: Dairidae (the living fossil
A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. ...
(4, 8†)
***
Dorippoidea
Dorippoidea is a superfamily of crabs. The earliest fossils attributable to the Dorippoidea date from the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geo ...
(101, 73†)
***
Eriphioidea
Eriphioidea is a superfamily of crabs, containing the six families Dairoididae, Eriphiidae, Hypothalassiidae, Menippidae, Oziidae and Platyxanthidae. They are united by a number of characters, including a marked difference in size between ...
(67, 14†)
***
Gecarcinucoidea
Gecarcinucoidea is a superfamily of freshwater crabs. Its members have been grouped into families in various ways, with some authors recognizing families such as "Deckeniidae", "Sundathelphusidae", and "Parathelphusidae", but now only the family ...
(349)
***
Goneplacoidea
Goneplacoidea is a superfamily of crabs containing 11 extant families, and two families known only from fossils (marked "†").
* Acidopsidae
* † Carinocarcinoididae
* Chasmocarcinidae
* Conleyidae
* Euryplacidae
* Goneplacidae
* Litoch ...
(182, 94†)
***
Hexapodoidea
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be dis ...
(21, 25†)
***
Leucosioidea
Leucosioidea is a superfamily of crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entir ...
(488, 113†)
***
Majoidea
The Majoidea are a superfamily of crabs which includes the various spider crabs.
Taxonomy
In "''A classification of living and fossil genera of decapod crustaceans''" De Grave and colleagues divided Majoidea into six families:
* Family Epial ...
(980, 89†)
***
Orithyioidea
''Orithyia sinica'', sometimes called tiger crab or the tiger face crab, is a "singularly unusual" species of crab, whose characteristics warrant its separation into a separate genus, family and even superfamily, having previously been included ...
(1)
***
Palicoidea
Palicoidea is a superfamily (zoology), superfamily of crabs, comprising the two families Crossotonotidae and Palicidae. Together, they contain 13 genera, including two genera in the Palicidae known only from fossils. The two families were previou ...
(63, 6†)
***
Parthenopoidea
Parthenopidae is a family of crabs, placed in its own Superfamily (taxonomy), superfamily, Parthenopoidea. It comprises nearly 40 genera, divided into two subfamilies, with three genera ''incertae sedis'':
;Daldorfiinae Ng & Rodríguez, 1986
* ...
(144, 36†)
***
Pilumnoidea
Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods. The earlie ...
(405, 47†)
***
Portunoidea (455, 200†)
***
Potamoidea (662, 8†)
***
Pseudothelphusoidea
Pseudothelphusidae is a family of freshwater crabs found chiefly in mountain streams in the Neotropics. They are believed to have originated in the Greater Antilles and then crossed to Central America via a Pliocene land bridge.
Parasitology
Pse ...
(276)
***
Pseudozioidea
Pseudozioidea is a superfamily (zoology), superfamily of crabs, formerly treated in the Eriphioidea, Carpilioidea, Xanthoidea, Pilumnoidea and Goneplacoidea. A number of fossils from the Eocene onwards are known from the family Pseudoziidae. Elev ...
(22, 6†)
***
Retroplumoidea
Retroplumidae is a family of heterotrematan crabs, placed in their own (monotypic) superfamily, Retroplumoidea.
Classification
Eight genera are recognised, of which all but two are only known from fossils:
*'' Archaeopus'' † Rathbun, 1908
*'' ...
(10, 27†)
***
Trapezioidea
Trapezioidea is a superfamily of crabs. Its members live symbiotically with corals, and have a fossil record stretching back to the Eocene.
Families
The World Register of Marine Species
The World Register of Marine Species (WoRMS) is a tax ...
(58, 10†)
***
Trichodactyloidea
Trichodactylidae is a family of crabs, in its own superfamily, Trichodactyloidea. They are all freshwater animals from Central and South America, including some offshore islands, such as Ilhabela, São Paulo. Only one of the 50 species is known ...
(50)
***
Xanthoidea (736, 134†)
** Subsection
Thoracotremata
***
Cryptochiroidea
Cryptochiridae is a family of crabs known commonly as gall crabs or coral gall crabs. They live inside dwellings in corals and cause the formation of galls in the coral structure.Johnsson, R., et al. (2006)The association of two gall crabs (Brac ...
(46)
***
Grapsoidea
The Grapsoidea are a superfamily of crabs; they are well known and contain many taxa which are terrestrial (land-living), semiterrestrial (taking to the sea only for reproduction), or limnic (living in fresh water). Another well-known member wit ...
(493, 28†)
***
Ocypodoidea
The Ocypodoidea, or ocypoid crabs, are a superfamily of crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail ...
(304, 14†)
***
Pinnotheroidea (304, 13†)
Recent studies have found the following
superfamilies and
families to not be
monophyletic, but rather
paraphyletic or
polyphyletic:
*The
Thoracotremata superfamily
Grapsoidea
The Grapsoidea are a superfamily of crabs; they are well known and contain many taxa which are terrestrial (land-living), semiterrestrial (taking to the sea only for reproduction), or limnic (living in fresh water). Another well-known member wit ...
is polyphyletic
*The
Thoracotremata superfamily
Ocypodoidea
The Ocypodoidea, or ocypoid crabs, are a superfamily of crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail ...
is polyphyletic
*The
Heterotremata superfamily
Calappoidea
Calappoidea is a superfamily of crabs comprising the two families Calappidae and Matutidae. The earliest fossils attributable to the Calappoidea date from the Aptian
The Aptian is an age in the geologic timescale or a stage in the stratig ...
is polyphyletic
*The
Heterotremata superfamily
Eriphioidea
Eriphioidea is a superfamily of crabs, containing the six families Dairoididae, Eriphiidae, Hypothalassiidae, Menippidae, Oziidae and Platyxanthidae. They are united by a number of characters, including a marked difference in size between ...
is polyphyletic
*The
Heterotremata superfamily
Goneplacoidea
Goneplacoidea is a superfamily of crabs containing 11 extant families, and two families known only from fossils (marked "†").
* Acidopsidae
* † Carinocarcinoididae
* Chasmocarcinidae
* Conleyidae
* Euryplacidae
* Goneplacidae
* Litoch ...
is polyphyletic
*The
Heterotremata superfamily
Potamoidea is paraphyletic with respect to
Gecarcinucoidea
Gecarcinucoidea is a superfamily of freshwater crabs. Its members have been grouped into families in various ways, with some authors recognizing families such as "Deckeniidae", "Sundathelphusidae", and "Parathelphusidae", but now only the family ...
, which is resolved by placing
Gecarcinucidae within
Potamoidea
*The
Majoidea
The Majoidea are a superfamily of crabs which includes the various spider crabs.
Taxonomy
In "''A classification of living and fossil genera of decapod crustaceans''" De Grave and colleagues divided Majoidea into six families:
* Family Epial ...
families
Epialtidae
Epialtidae is a family of crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely unde ...
,
Mithracidae and
Majidae are polyphyletic with respect to each other
*The
Dromioidea
Dromioidea is a superfamily of crabs mostly found in Madagascar. Dromioidea belongs the group Dromiacea, taxonomically ranked as a section, which is the most basal grouping of Brachyura crabs. Dromiacea likely diverged from the rest of Brac ...
family
Dromiidae
Dromiidae is a family of crabs, often referred to as sponge crabs. They are small or medium-sized crabs which get their name from the ability to shape a living sponge into a portable shelter for themselves.Encarta Reference Library Premium 2005 D ...
may be paraphyletic with respect to
Dynomenidae
Dynomenidae is a family of crabs in the superfamily Dromioidea mostly found in Madagascar. There are nineteen genera in this family: five extant and fourteen known from fossil
A fossil (from Classical Latin , ) is any preserved remains, i ...
*The
Homoloidea
Homoloidea is a superfamily of dromiacean crabs. Homoloidea belongs the group Dromiacea, taxonomically ranked as a section, and is the sister group to Dromioidea. Dromiacea is the most basal grouping of Brachyura crabs, and likely diverged ...
family
Homolidae
The family Homolidae, known as carrier crabs or porter crabs, contains 14 genera of marine crabs. They mostly live on the continental slope and continental shelf, and are rarely encountered. Members of the Homolidae have their fifth pereiopods ( ...
is paraphyletic with respect to
Latreilliidae
Latreilliidae is a small family of crabs. They are relatively small, long-legged crabs found on soft bottoms at depths of up in mostly tropical and subtemperate waters around the world. Their carapace is very small and doesn’t cover the bases ...
*The
Xanthoidea family
Xanthidae is paraphyletic with respect to
Panopeidae
Cultural influences
Both the
constellation Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
and the
astrological sign Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
are named after the crab, and depicted as a crab.
William Parsons, 3rd Earl of Rosse drew the
Crab Nebula in 1848 and noticed its similarity to the animal; the
Crab Pulsar lies at the centre of the nebula. The
Moche people of ancient
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = National seal
, national_motto = "Firm and Happy f ...
worshipped nature, especially the sea, and often depicted crabs in their art. In
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities o ...
,
Karkinos was a crab that came to the aid of the
Lernaean Hydra as it battled
Heracles
Heracles ( ; grc-gre, Ἡρακλῆς, , glory/fame of Hera), born Alcaeus (, ''Alkaios'') or Alcides (, ''Alkeidēs''), was a divine hero in Greek mythology, the son of Zeus and Alcmene, and the foster son of Amphitryon.By his adoptiv ...
. One of
Rudyard Kipling
Joseph Rudyard Kipling ( ; 30 December 1865 – 18 January 1936)'' The Times'', (London) 18 January 1936, p. 12. was an English novelist, short-story writer, poet, and journalist. He was born in British India, which inspired much of his work.
...
's ''
Just So Stories
''Just So Stories for Little Children'' is a 1902 collection of origin stories by the British author Rudyard Kipling. Considered a classic of children's literature, the book is among Kipling's best known works.
Kipling began working on the ...
'', ''The Crab that Played with the Sea'', tells the story of a gigantic crab who made the waters of the sea go up and down, like the tides. The auction for the crab quota in 2019, Russia is the largest revenue auction in the world except the spectrum auctions. In
Malay mythology (as related by
Hugh Clifford
Sir Hugh Charles Clifford, (5 March 1866 – 18 December 1941) was a British colonial administrator.
Early life
Clifford was born in Roehampton, London, the sixth of the eight children of Major-General Sir Henry Hugh Clifford and his wife ...
to
Walter William Skeat), ocean tides are believed to be caused by water rushing in and out of a hole in the Navel of the Seas (''Pusat Tasek''), where "there sits a gigantic crab which twice a day gets out in order to search for food".
The
Kapsiki people of North Cameroon use the way crabs handle objects for
divination .
The term ''
crab mentality'' is derived from a type of detrimental social behavior observed in crabs.
See also
*
Carcinisation
*
Anomura
References
External links
*
{{Authority control
Edible crustaceans
Commercial crustaceans
Extant Jurassic first appearances
Articles containing video clips