Crab spider

Crab spiders
Ozyptila praticola
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Superfamily: Thomisoidea
Family: Thomisidae
Sundevall, 1833

many others

170 genera, > 2,000 species

Crab spider is a common name applied loosely to many species of spiders, but most nearly consistently to members of the family Thomisidae. Among the Thomisidae it refers most often to the familiar species of "flower crab spiders", though not all members of the family are limited to ambush hunting in flowers.


Crab spider as a name in common use

Rationalisation for the name crab spider is generally subjective and anecdotal. It is commonly said to refer to a fancied resemblance to crabs, or to the way such spiders hold their two front pairs of legs, or their ability to scuttle sideways or backwards. Some spiders so called have bodies that are flattened and angular. At all events, the Thomisidae are the family most generally referred to as "crab spiders". However, some members of the Sparassidae are called giant crab spiders, Selenopidae are called wall crab spiders, and various members of the Sicariidae are sometimes called six-eyed crab spiders.[1] Some unrelated Orb-weaver spider species such as Gasteracantha cancriformis also are commonly called "crab spiders."

Such names are of little biological significance, and in this article the emphasis is on the Thomisidae.

Crab spider biology

None of the crab spiders mentioned build webs to trap prey, though all of them produce silk for drop lines and sundry reproductive purposes; some are wandering hunters and the most widely known are ambush predators. Some species sit on or beside flowers or fruit, where they grab visiting insects. Individuals of some species, such as Misumena vatia, are able to change color over a period of some days, to match the flower on which they are sitting. Some species frequent promising positions among leaves or bark, where they await prey, and some of them will sit in the open, where they are startlingly good mimics of bird droppings. However, note that these members of the family Thomisidae are not to be confused with the spiders that generally are called bird dropping spiders, not all of which are close relatives of crab spiders.

Other species of crab spiders with flattened bodies, either hunt in the crevices of tree trunks or under loose bark, or shelter under such crevices by day, and come out at night to hunt. Members of the genus Xysticus hunt in the leaf litter on the ground. In each case, crab spiders use their powerful front legs to grab and hold onto prey while paralyzing it with a venomous bite.

The spider family Aphantochilidae was incorporated into the Thomisidae in the late 1980s. Aphantochilus species mimic Cephalotes ants, on which they prey.

The spiders of Thomisidae are not known to be harmful to humans. However, spiders of an unrelated genus, Sicarius, which are sometimes referred to as "crab spiders", or "six-eyed crab spiders", are close cousins to the recluse spiders, and are highly venomous, though human bites are rare.

Female Crab Spider Genus Thomisus Family Thomisidae. Sitting in ambush in a Felicia flower.
A typical female Crab Spider in the genus Thomisus
Female Crab Spider Genus Thomisus Family Thomisidae. Feeding on housefly snatched live from finger of photographer.
Thomisus sp. Male feeding on midge. The fingerprint gives some idea of the scale.
Thomisus sp female with male on back awaiting opportunity to mate, probably when she next feeds. Note the shape of the distal ends of his pedipalps.
A crab spider in the genus Thomisus, sitting in ambush behind a Lavandula flower too small to accommodate her


Crab spider'Xysticus sp.jpg

The following subfamilies are recognized:

  • Aphantochilinae (3 genera)
  • Bominae Ono, 1984 (9 genera)
  • Dietinae (32 genera)
  • Stephanopinae (35 genera)
  • Stiphropodinae (3 genera)
  • Strophiinae (8 genera)
  • Thomisinae (67 genera)
  • incertae sedis
  • Ansiea Lehtinen,
  • Carcinarachne Schmidt, 1956
  • Cozyptila Lehtinen & Marusik, 2005
  • Ebelingia Lehtinen, 2005
  • Facundia Petrunkevitch, 1942 † (fossil)
  • Fiducia Petrunkevitch, 1942 † (fossil)
  • Henriksenia Lehtinen, 2005
  • Hexommulocymus Caporiacco, 1955
  • Ledouxia Lehtinen, 2005
  • Mastira Thorell, 1891
  • Megapyge Caporiacco, 1947
  • Modysticus Gertsch, 1953
  • Rejanellus Lise, 2005
  • Syphax Koch & Berendt, 1854 † (fossil)
  • Tarrocanus Simon, 1895
  • Taypaliito Barrion & Litsinger, 1995
Crab Spider female, family Thomisidae, genus Synema. Awaiting prey on Lavandula.

See also


  1. ^ Filmer, Martin (1997). Southern African Spiders. City: BHB International / Struik. ISBN 1868251888. 
  • Biolib family Thomisidae
  • Lise, A.A. (2005). Rejanellus, a new genus of Thomisidae (Araneae, Stephanopinae). Iheringia, Sér. Zool. 95(2):151-164. PDF

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Crab spider — Crab Crab (kr[a^]b), n. [AS. crabba; akin to D. krab, G. krabbe, krebs, Icel. krabbi, Sw. krabba, Dan. krabbe, and perh. to E. cramp. Cf. {Crawfish}.] 1. (Zo[ o]l.) One of the brachyuran Crustacea. They are mostly marine, and usually have a broad …   The Collaborative International Dictionary of English

  • crab spider — n. any of a family (Thomisidae) of spiders that move sideways like crabs …   English World dictionary

  • crab spider — any crab shaped spider of the family Thomisidae, characterized by its sideways manner of moving. [1860 65] * * * ▪ spider  family of spiders (order Araneida) that are crablike in shape and, like many crabs, often walk sideways or backward. The… …   Universalium

  • crab spider — noun a spider with long front legs that moves with a crablike sideways motion. [Family Thomisidae: many species.] …   English new terms dictionary

  • crab spider — /ˈkræb spaɪdə/ (say krab spuyduh) noun a well camouflaged spider, Synalus angustus, found on the bark of trees, which does not build a web but catches insects with its spined legs …   Australian English dictionary

  • crab spider — noun Date: 1861 any of a family (Thomisidae) of spiders that resemble crabs in shape and in being able to walk forward, backward, and sideways …   New Collegiate Dictionary

  • crab spider — noun Any species of the family Thomisidae, spiders that hunt in flowers …   Wiktionary

  • crab spider — noun : any of the numerous spiders that make up the family Thomisidae and resemble crabs in attitude and in ability to run sideways …   Useful english dictionary

  • Flower crab spider — Misumena vatia female Scientific classification Kingdom …   Wikipedia

  • Wall crab spider — Taxobox name = Wall crab spiders image width = 250px image caption = Selenops sp. regnum = Animalia phylum = Arthropoda classis = Arachnida ordo = Araneae zoosectio = Entelegynae superfamilia = Selenopioidea familia = Selenopidae familia… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.