Majidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

s, comprising around 700 marine

Ocean

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 with a carapace

Carapace

A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...

 that is longer than it is broad, and which forms a point at the front. The legs

Arthropod leg

The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...

 can be very long in some species, leading to the name "spider crab

Spider crab

The term spider crab can refer to various species of crab in the family Majidae. See crab spider for spiders of the Thomisidae family.*Japanese spider crab , the largest living species of crab, found on the bottom of the Pacific Ocean*Libinia emarginata, the portly spider crab, a species of crab...

". The exoskeleton

Exoskeleton

An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...

 is covered with bristles to which the crab attaches algae and other items to act as camouflage

Camouflage

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

.

Genera

The over 200 extant and over 50 extinct species are divided among 52 genera in 5 subfamilies:

Eurynolambrinae Števčić, 1994

• Eurynolambrus H. Milne-Edwards & Lucas, 1841

Majinae Samouelle, 1819

• Ageitomaia Griffin & Tranter, 1986
• Anacinetops Miers, 1879
• Choniognathus Rathbun, 1932
• Cyclax Dana, 1851
• Entomonyx Miers, 1884
• Eurynome Leach, 1814
• Jacquinotia Rathbun, 1915
• Kasagia Richer de Forges & Ng, 2007
• Kimbla Griffin & Tranter, 1986
• Leptomithrax Miers, 1876
• Maiopsis Faxon, 1893
• Maja
  Maja (genus)
  Maja is a genus of majid crabs, comprising the following extant species:*Maja africana Griffin & Tranter, 1996*Maja bisarmata Rathbun, 1916*Maja capensis Ortmann, 1894*Maja compressipes...
  
  Lamarck, 1801
• Majella Ortmann, 1893
• Microhalimus Haswell, 1880
• Naxia Latreille, 1825
• Notomithrax
  Notomithrax
  Notomithrax is a genus of crabs of the family Majidae, containing four species:* Notomithrax minor * Notomithrax spinosus * Notomithrax peronii * Notomithrax ursus...
  
  Griffin, 1963
• Paraentomonyx T. Sakai, 1983
• Paramithrax H. Milne-Edwards, 1837
• Pippacirama Griffin & Tranter, 1986
• Prismatopus Ward, 1933
• Schizophroida T. Sakai, 1933
• Schizophrys White, 1848
• Seiitaoides Griffin & Tranter, 1986
• Temnonotus A. Milne-Edwards, 1875
• Teratomaia Griffin & Tranter, 1986
• Thersandrus Rathbun, 1897
• Tumulosternum McCulloch, 1913
• Wilsonimaia † Blow & Manning, 1996

Micromaiinae † Beurlen, 1930

• Micromaia † Bittner, 1875
• Mithracia † Bell, 1858
• Pisomaja † Lőrenthey, in Lőrenthey & Beurlen, 1929

Mithracinae MacLeay, 1838

• Ala Lockington, 1877
• Antarctomithrax † Feldmann, 1994
• Coelocerus A. Milne-Edwards, 1875
• Cyclocoeloma Miers, 1880
• Cyphocarcinus A. Milne-Edwards, 1868
• Leptopisa Stimpson, 1871
• Macrocoeloma Miers, 1879
• Micippa Leach, 1817
• Microphrys Milne-Edwards, 1851
• Mithraculus White, 1847
• Mithrax A. G. Desmarest, 1823
• Nemausa A. Milne-Edwards, 1875
• Paranaxia Rathbun, 1924
• Picroceroides Miers, 1886
• Stenocionops A. G. Desmarest, 1823
• Teleophrys Stimpson, 1860
• Thoe Bell, 1836
• Tiarinia Dana, 1851

Planoterginae Števčić, 1991

• Hemus
  Hemus
  Hemus is a genus of spider crab in the family Majidae. It contains four species:* Hemus analogus Rathbun, 1898* Hemus cristulipes A. Milne-Edwards, 1875* Hemus finneganae Garth, 1958* Hemus magalae Windsor & Felder, 2011...
  
  A. Milne-Edwards, 1875
• Planotergum Balss, 1935