Crabs Temporal range: Jurassic–Recent PreЄ Є O S D C P T J K Pg N
Liocarcinus vernalis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Brachyura Linnaeus, 1758
Sections & subsections [1]
Dromiacea Raninoida Cyclodorippoida Eubrachyura Heterotremata Thoracotremata

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (Greek: βραχύς / brachys = short,^[2] οὐρά / οura = tail^[3]), or where the reduced abdomen is entirely hidden under the thorax. Many other animals with similar names – such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs and crab lice – are not true crabs.

Evolution[link]

Gecarcinus quadratus, a land crab from Central and South America

Crabs are generally covered with a thick exoskeleton, and armed with a single pair of chelae (claws). Crabs are found in all of the world's oceans, while many crabs live in fresh water and on land, particularly in tropical regions. Crabs vary in size from the pea crab, a few millimetres wide, to the Japanese spider crab, with a leg span of up to 4 metres (13 ft).^[4]

About 850 species of crab are freshwater, terrestrial or semi-terrestrial species;^[5] they are found throughout the world's tropical and semi-tropical regions. They were previously thought to be a monophyletic group, but are now believed to represent at least two distinct lineages, one in the Old World and one in the New World.^[6]

The earliest unambiguous crab fossils date from the Jurassic,^[7] although Carboniferous Imocaris, known only from its carapace, may be a primitive crab.^[8] The radiation of crabs in the Cretaceous and afterward may be linked either to the break-up of Gondwana or to the concurrent radiation of bony fish, crabs' main predators.^[9]

Sexual dimorphism[link]

The underside of a male (top) and a female (bottom) individual of Pachygrapsus marmoratus, showing the difference in shape of the abdomen

Crabs often show marked sexual dimorphism. Males often have larger claws,^[10] a tendency which is particularly pronounced in the fiddler crabs of the genus Uca (Ocypodidae). In fiddler crabs, males have one claw which is greatly enlarged and which is used for communication, particularly for attracting a mate.^[11] Another conspicuous difference is the form of the pleon (abdomen); in most male crabs, this is narrow and triangular in form, while females have a broader, rounded abdomen.^[12] This is due to the fact that female crabs brood fertilised eggs on their pleopods.

Behaviour[link]

Carpilius convexus consuming Heterocentrotus trigonarius in Hawaii

Crabs typically walk sideways^[13] (a behaviour which gives us the word crabwise). This is because of the articulation of the legs which makes a sidelong gait more efficient.^[14] However, some crabs walk forwards or backwards, including raninids,^[15] Libinia emarginata^[16] and Mictyris platycheles.^[13] Some crabs, notably the Portunidae and Matutidae, are also capable of swimming.^[17]

Crabs are mostly active animals with complex behaviour patterns. They can communicate by drumming or waving their pincers. Crabs tend to be aggressive towards one another and males often fight to gain access to females.^[18] On rocky seashores, where nearly all caves and crevices are occupied, crabs may also fight over hiding holes.^[19]

Crabs are omnivores, feeding primarily on algae,^[20] and taking any other food, including molluscs, worms, other crustaceans, fungi, bacteria 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.^[21][22]

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.^[23]

Human consumption[link]

Fisheries[link]

Fishermen sorting edible crabs at Fionnphort, Scotland

Crabs make up 20% of all marine crustaceans caught, farmed, and consumed worldwide, amounting to 1½ million tonnes 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 (Metacarcinus magister) and Scylla serrata, each of which yields more than 20,000 tonnes annually.^[24]

Cookery[link]

Crab masala from Karnataka, India

Crabs are prepared and eaten as a dish in several 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 and/or legs are eaten. The latter is particularly common for larger crabs, such as the snow crab. Mostly in East Asian cultures, the roe of the female crab is also eaten, which usually appears orange or yellow in color in fertile crabs.

In some regions spices improve the culinary experience. In Asia, masala crab and chilli crab are examples of heavily spiced dishes. In the Chesapeake Bay region, blue crab is often eaten with Old Bay Seasoning.

For the British dish Cromer 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 a flour mix, creating a crab cake.

Crabs are also used in bisque, a global dish of French origin.

Pain[link]

Live crabs are often boiled. In 2005, Norwegian scientists concluded that lobsters cannot feel pain.^[25] However, later research suggests that crustaceans are indeed able to feel and remember pain.^[26][27]

Classification[link]

The infraorder Brachyura contains 6,793 species in 93 families,^[17] as many as the remainder of the Decapoda.^[28] The evolution of crabs is characterised by an increasingly robust body, and a reduction in the abdomen. 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. However, since crabs use the first two pairs of pleopods (abdominal appendages) for sperm transfer, this arrangement has changed. As the male abdomen evolved into a narrower shape, the gonopores have moved towards the midline, away from the legs, and onto the sternum.^[29] 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 those crabs where the female, but not male, gonopores are situated on the sternum, form a monophyletic group.^[28]

Superfamilies[link]

Dromia personata (Dromiacea: Dromiidae)

Ranina ranina (Raninoida: Raninidae)

Corystes cassivelaunus (Heterotremata: Corystidae)

Ocypode quadrata (Thoracotremata: Ocypodidae)

Numbers of extant and extinct (†) species are given in brackets.^[17] The superfamily Eocarcinoidea, containing Eocarcinus and Platykotta, was formerly thought to contain the oldest crabs; it is now considered part of the Anomura.^[30]

• 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†)
  • Subsection Thoracotremata
  • Cryptochiroidea (46)
  • Grapsoidea (493, 28†)
  • Ocypodoidea (304, 14†)
  • Pinnotheroidea (304, 13†)

Cultural influences[link]

Both the constellation Cancer and the astrological sign Cancer 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.^[31]

The Moche people of ancient Peru worshipped nature, especially the sea,^[32] and often depicted crabs in their art.^[33] In Greek mythology, Karkinos was a crab that came to the aid of the Lernaean Hydra as it battled Heracles.

References[link]

External links[link]

Crustaceans portal

• Media related to Brachyura at Wikimedia Commons
• Data related to Brachyura at Wikispecies

v t e Superfamilies of Infraclass Brachyura (true crabs) Kingdom Animalia · Phylum Arthropoda · Class Malacostraca · Order Decapoda · Suborder Pleocyemata Dromiacea Dakoticancroidea† · Dromioidea · Glaessneropsoidea† · Homolodromioidea · Homoloidea Raninoida Raninoidea Cyclodorippoida Cyclodorippoidea Eubrachyura Heterotremata Aethroidea · Bellioidea · Bythograeoidea · Calappoidea · Cancroidea · Carpilioidea · Cheiragonoidea · Componocancroidea† · Corystoidea · Dairoidea · Dorippoidea · Eriphioidea · Gecarcinucoidea · Goneplacoidea · Hexapodoidea · Leucosioidea · Majoidea · Orithyioidea · Palicoidea · Parthenopoidea · Pilumnoidea · Portunoidea · Potamoidea · Pseudothelphusoidea · Pseudozioidea · Retroplumoidea · Trapezioidea · Trichodactyloidea · Xanthoidea Thoracotremata Cryptochiroidea · Grapsoidea · Ocypodoidea · Pinnotheroidea

v t e Principal commercial fishery species groups Wild Large pelagic fish Mackerel Salmon Shark Swordfish Tuna albacore bigeye Atlantic bluefin Pacific bluefin southern bluefin skipjack yellowfin Forage fish Anchovy Capelin Herring Ilish Menhaden Sardines Shad Demersal fish Catfish Cod Atlantic Pacific Flatfish flounder halibut plaice sole turbot Haddock Mullet Orange roughy Pollock Smelt-whitings Toothfish Freshwater fish Carp Sturgeon Tilapia Trout Other wild fish Eel Whitebait more... Crustaceans Crab Krill Lobster Shrimp and prawn more... Molluscs Abalone Mussels Octopus Oysters Scallops Squid more... Echinoderms Sea cucumbers Sea urchin more... Farmed Carp bighead common crucian grass silver Catfish Freshwater prawns Mussels Oysters Salmon Atlantic salmon trout coho chinook Scallops Seaweed Shrimp Tilapia Commercial fishing World fish production Fishing topics Fisheries glossary

Ray William Johnson (born 1981-1982) is an American actor and comedian best known for his YouTube series Equals Three, in which he provides commentary on viral videos.^[2][3] Many of the videos featured on Equals Three are noted to have received an additional boost of popularity.^{[4][5][6][7][8]} As of May 2012, the RayWilliamJohnson channel is the most subscribed channel on YouTube,^[9][10] with over 5.4 million subscribers, and over 1.7 billion video views.^[11] In February 2011, one industry publication noted that Johnson currently had six of the top twenty most watched videos of the month.^[12]

Background[link]

Johnson graduated from Norman North High School in Oklahoma, in 1999,^[1] however Johnson's Youtube profile states he was born and raised in Oklahoma City, Oklahoma.^[13] In an interview with Wall Street Journal, Johnson says that he studied at Columbia University, as a history major,^[1] while his profile adds he was preparing to study law.^[13] While at Columbia, Johnson started his first formatted show, Equals Three, as a way to combine two popular video styles, watching viral videos and video bloggers.^[2]

Current projects[link]

[edit] Equals Three

Equals Three
Title card
Genre	Comedy
Created by	Ray William Johnson
Written by	Phil Haney Steve Greene Marvin Silbermintz Erin Schmalfeld Ilana Cohn Brandon Perna "Big Rob" Lance Patrick Ray William Johnson
Presented by	Ray William Johnson
Country of origin	United States
Language(s)	English Spanish (Igual a Tres)
No. of episodes	265 (as of March 3, 2012)
Production
Executive producer(s)	Ray William Johnson
Producer(s)	Erin Schmalfeld
Editor(s)	Brandon Perna
Broadcast
Original channel	RayWilliamJohnson
Original run	2008 (2008) – present
Chronology
Related shows	Breaking Your Favorite Martian Igual a Tres YFMTS
External links
Website

In Equals Three (stylized as "=3"), Ray William Johnson reviews, criticizes, and adds commentary to some of the internet's latest viral videos.^[3] Equals Three episodes are usually uploaded to his channel every Tuesday and Friday. In these episodes, Johnson interacts with his audience by posting a viewer-submitted "comment question of the day", then features five of his favorite comments in the preceding episode. Equals Three is on the most subscribed channel on YouTube, having over 5 million subscribers to date, and has been recognized by Guinness World Records.^[2][14][15] Because of his popularity, Equals Three episodes can consistently obtain several million views within a week. Johnson has been able to leverage his popularity to secure several celebrity guests on Equals Three, including Robin Williams,^[16] Gabriel Iglesias,^[17] Kal Penn,^[18] Margaret Cho,^[19] Bobby Lee,^[20] T.J. Miller,^[21] Garfunkel and Oates,^[22] John Cho,^[18] Jason Biggs,^[23] Andy Milonakis^[24] and Traphik.^[25]

Your Favorite Martian[link]

In January 2011, Johnson launched a collaborative YouTube channel called "YourFavoriteMartian", which features animated music videos.^{[26][27][dead link]} The songs are performed by a virtual band of four fictional cartoon characters: PuffPuff Humbert (vocals, voiced by Johnson), DeeJay (turntables), Axel Chains (drums), and Benatar (vocals, guitar/keytar).^[28] Johnson writes lyrics, raps, sings, composes beats, and sometimes collaborates with other musicians to produce the songs.^[29] The following is a list of music videos that have been released so far:

To date, Johnson has released 30 original songs, 1 remix, and 3 covers through the channel. As of May 2012, the channel has over 1.8 million subscribers, making it one of the most subscribed channels on YouTube, and over 372 million video views.^[30][31] Due to the rapid growth of popularity of the channel and the music videos getting more views than the Equals Three episodes, Johnson has commented in his Breaking Los Angeles video blog that he at some point hopes to have the music videos released weekly instead of bi-weekly.^[32]

[edit] Breaking

BreakingNYC is a former daily video blog or vlog that Johnson started in December 2009 while living in New York City. He made the vlogs almost daily until June 2010. After nearly a year-long hiatus, Johnson resumed contributing to the video blog channel, creating a new higher quality series with a similar format. The new series titled, Breaking Los Angeles and the Adventures of Puff Puff, was released every Friday and is filmed in Los Angeles. Johnson often featured notable guests in his new series, including rappers Wax, Hoodie Allen and Dumbfoundead, slam poet George Watsky, comedian Gabriel Iglesias, and actor/director Bobcat Goldthwait. After Johnson took a three-month hiatus from making videos for the channel, a third season of Breaking Los Angeles (retitled to Breaking: Season 3), premiered on December 14, 2011.

References[link]

External links[link]

Internet portal

• Official Site