Thomisidae

"Crab spider" redirects here; not to be confused with spider crab.

The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of this family are also known as flower spiders or flower crab spiders.^[3]

Thomisidae Temporal range: Palaeogene–present PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Thomisidae Sundevall, 1833[1]
Diversity[2]
171 genera, 2,167 species

Description

Crab spider feeding on a Junonia atlites butterfly in a Zinnia elegans flower

Camouflaging on a yellow flower, a Misumenops calinurus ambushes a butterfly in Porto Alegre, Brazil.

Members of this family of spiders do not spin webs, and are ambush predators. The two front legs are usually longer and more robust than the rest of the legs. The back two legs are smaller, and are usually covered in a series of strong spines.^[4] They have dull colorations such as brown, grey, or very bright green, pink, white or yellow. They gain their name from the shape of their body, and they usually move sideways or backwards.^[5] These spiders are quite easy to identify and can very rarely be confused with Sparassidae family, though the crab spiders are usually smaller.

Etymology

Spiders in this family are called "crab spiders" due to their resemblance to crabs, the way such spiders hold their two front pairs of legs, and their ability to scuttle sideways or backwards.^[3][6] The Thomisidae are the family most generally referred to as "crab spiders", though some members of the Sparassidae are called "giant crab spiders", the Selenopidae are called "wall crab spiders", and various members of the Sicariidae are sometimes called "six-eyed crab spiders".^[7] Some distantly related orb-weaver spider species such as Gasteracantha cancriformis also are sometimes called "crab spiders".

Behavior

Crab spider waiting in ambush, Behbahan, Iran

Crab spider on Queen Ann’s lace

Crab spider jumps with safety line, on yellow ironweed. Repeated at variable slow motion to better see silk line. Spider probably Misumessus oblongus.

A crab-spider is spotted with a bumblebee as its prey underneath a leaf.

Thomisidae do not 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 and Thomisus spectabilis, 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 sit in the open, where they are startlingly good mimics of bird droppings. However, 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 on to prey while paralysing 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 a distantly related 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.

Sexual dimorphism

Several different types of sexual dimorphism have been recorded in crab spiders. Some species exhibit color dimorphisms;^[8] however, the most apparent dimorphism is the difference in size between males and females. In some species, this is relatively small; females of Misumena vatia are roughly twice the size of their male counterparts.^[9] In other cases, the difference is extreme; on average, female Thomisus onustus are more than 60 times as massive as the males.^[10]

Several hypothesized explanations are given for the evolution of sexual size dimorphisms in the Thomisidae and other sister taxa.^[11] The most widely acknowledged hypothesis for female growth is the fecundity hypothesis:^[12] selection favors larger females so they can produce more eggs and healthier offspring. Because males do not carry and lay eggs, a growth in size does not confer a fitness advantage.^[12]

However, sexual size dimorphism may be a result of male dwarfism. The gravity hypothesis states that the smaller size allows the male to travel with greater ease, providing him with an increased opportunity to find mates.^[13] Females are comparatively stationary, and their larger size allows them to capture larger prey, such as butterflies and bees, granting females the additional nutrients necessary for egg production.^[10]

Other hypotheses propose that sexual size dimorphism evolved by chance, and no selective advantage exists to larger females or smaller males.^[14]

Genera

• 
  Angaeus sp., Karnataka, India
• 
  Camaricus sp., Goa, India
• 
  female Misumena vatia
• 
  Nyctimus bistriatus, Indonesia

• 
  Ant-mimic Amyciaea sp., Karnataka, India
• 
  Phyrnarachne sp. mimicking bird-dropping, Karnataka, India
• 
  Runcinia sp., Goa, India

As of October 2025^[update], this family includes 171 genera:^[1]

• Acentroscelus Simon, 1886 – South America
• Acrotmarus Tang & Li, 2012 – China
• Alcimochthes Simon, 1886 – China, Japan, Taiwan, Malaysia, Singapore, Vietnam
• Amyciaea Simon, 1886 – Ivory Coast, Sierra Leone, Indonesia, Singapore, Vietnam, India, Australia, New Guinea
• Angaeus Thorell, 1881 – Asia
• Ansiea Lehtinen, 2004 – Africa, Saudi Arabia, Sao Tomé
• Ansistaria Sherwood, 2022 – Africa
• Aphantochilus O. Pickard-Cambridge, 1871 – Argentina, Brazil
• Apyretina Strand, 1929 – Madagascar
• Australomisidia Szymkowiak, 2014 – Australia
• Avelis Simon, 1895 – South Africa
• Bassaniana Strand, 1928 – China, Japan, Korea, Europe, North America
• Bassaniodes Pocock, 1903 – Egypt, West Africa, Asia, Europe
• Boliscus Thorell, 1891 – Asia, New Caledonia
• Bomis L. Koch, 1874 – India, Australia
• Bonapruncinia Benoit, 1977 – St. Helena
• Boomerangiana Szymkowiak & Sherwood, 2021 – Australia
• Borboropactus Simon, 1884 – Africa, Asia, Papua New Guinea
• Bucranium O. Pickard-Cambridge, 1881 – Cuba, Guatemala, Mexico, South America
• Camaricus Thorell, 1887 – Africa, China, Indonesia, Philippines, Vietnam, Bangladesh, India, New Caledonia
• Cebrenninus Simon, 1887 – Asia, West Africa
• Ceraarachne Keyserling, 1880 – Brazil, Colombia
• Cetratus Kulczyński, 1911 – Australia, New Guinea
• Coenypha Simon, 1895 – Argentina, Chile
• Coriarachne Thorell, 1870 – China, Japan, Korea, Caucasus, Turkey, Russia, North America
• Corynethrix L. Koch, 1876 – Australia
• Cozyptila Lehtinen & Marusik, 2005 – Vietnam, Caucasus, Turkey, Europe
• Crockeria Benjamin, 2016 – Indonesia, Malaysia
• Cymbacha L. Koch, 1874 – Sri Lanka, Australia, New Guinea
• Cymbachina Bryant, 1933 – New Zealand
• Cynathea Simon, 1895 – Africa
• Cyriogonus Simon, 1886 – Madagascar
• Deltoclita Simon, 1887 – Brazil, Peru
• Demogenes Thorell, 1895 – Indonesia, India, New Guinea, Vanuatu
• Diaea Thorell, 1869 – Africa, Asia, Russia, United States, Oceania, Colombia
• Dietopsa Strand, 1932 – India
• Dimizonops Pocock, 1903 – Yemen
• Diplotychus Simon, 1903 – Madagascar
• Domatha Simon, 1895 – Philippines, New Guinea
• Ebelingia Lehtinen, 2004 – China, Japan, Korea, Russia
• Ebrechtella Dahl, 1907 – Asia, Russia, Portugal
• Emplesiogonus Simon, 1903 – Madagascar
• Epicadinus Simon, 1895 – Trinidad and Tobago, Panama, Mexico, South America
• Epicadus Simon, 1895 – Mexico to South America
• Epidius Thorell, 1877 – Africa, Asia
• Erissoides Mello-Leitão, 1929 – Brazil
• Erissus Simon, 1895 – Brazil, Peru, Venezuela
• Felsina Simon, 1895 – Cameroon, Senegal, Sierra Leone
• Firmicus Simon, 1895 – Africa, Vietnam, Iran, Israel, Spain, France
• Geraesta Simon, 1889 – Africa
• Gnoerichia Dahl, 1907 – Cameroon
• Haedanula Caporiacco, 1941 – Ethiopia
• Haplotmarus Simon, 1909 – Vietnam
• Hedana L. Koch, 1874 – Indonesia, Malaysia, Myanmar, Sri Lanka, Oceania, Venezuela
• Henriksenia Lehtinen, 2004 – Indonesia, Malaysia, Singapore, Papua New Guinea
• Herbessus Simon, 1903 – Madagascar
• Heriaesynaema Caporiacco, 1939 – Ethiopia
• Heriaeus Simon, 1875 – Africa, Asia, Europe
• Heterogriffus Platnick, 1976 – Angola, Democratic Republic of the Congo, Uganda
• Hewittia Lessert, 1928 – Africa
• Hexommulocymus Caporiacco, 1955 – Venezuela
• Holopelus Simon, 1886 – Africa, Indonesia, India, Sri Lanka
• Ibana Benjamin, 2014 – China, Indonesia, Malaysia
• Indosmodicinus Sen, Saha & Raychaudhuri, 2010 – China, India
• Indoxysticus Benjamin & Jaleel, 2010 – China, India, Sri Lanka
• Iphoctesis Simon, 1903 – Madagascar
• Isala L. Koch, 1876 – Australia
• Isaloides F. O. Pickard-Cambridge, 1900 – Cuba, Hispaniola, Panama, Mexico
• Kryptochroma Machado, 2021 – Brazil, Colombia, French Guiana
• Lampertia Strand, 1907 – Madagascar
• Latifrons Kulczyński, 1911 – Indonesia
• Ledouxia Lehtinen, 2004 – Mauritius, Réunion
• Loxobates Thorell, 1877 – Asia
• Loxoporetes Kulczyński, 1911 – Indonesia, Australia
• Lycopus Thorell, 1895 – China, Japan, Indonesia, Myanmar, Singapore, India, New Guinea
• Lysiteles Simon, 1895 – Asia, Russia
• Massuria Thorell, 1887 – China, Japan, Myanmar, India
• Mastira Thorell, 1891 – Asia, Australia, Samoa
• Mecaphesa Simon, 1900 – North America, Chile, Galapagos
• Megapyge Caporiacco, 1947 – Guyana
• Metadiaea Mello-Leitão, 1929 – Brazil
• Micromisumenops Tang & Li, 2010 – China
• Misumena Latreille, 1804 – Africa, Asia, Europe, United States, Mexico, South America, New Guinea, Papua New Guinea
• Misumenoides F. O. Pickard-Cambridge, 1900 – India, North to South America
• Misumenops F. O. Pickard-Cambridge, 1900 – Africa, Asia, North America
• Misumessus Banks, 1904 – Bermuda, Dominica, Puerto Rico, North America, Grenadines?
• Modysticus Gertsch, 1953 – Mexico, United States
• Monaeses Thorell, 1869 – Africa, Asia, Bulgaria, Ukraine, Greece, Australia, Guyana
• Musaeus Thorell, 1890 – Indonesia
• Mystaria Simon, 1895 – Africa
• Narcaeus Thorell, 1890 – Indonesia
• Nyctimus Thorell, 1877 – South Africa, Indonesia, Malaysia, Thailand, Borneo
• Ocyllus Thorell, 1887 – Myanmar
• Onocolus Simon, 1895 – South America
• Ostanes Simon, 1895 – Ivory Coast, Sierra Leone
• Oxytate L. Koch, 1878 – Africa, Asia, Russia, Australia
• Ozyptila Simon, 1864 – Africa, Asia, Europe, North America
• Pactactes Simon, 1895 – Eastern Africa, South Africa, Ivory Coast
• Pagida Simon, 1895 – Indonesia, Thailand, India, Sri Lanka, Borneo
• Parabomis Kulczyński, 1901 – Africa
• Parasmodix Jézéquel, 1966 – Africa
• Parastrophius Simon, 1903 – Cameroon, Equatorial Guinea, Pakistan
• Parasynema F. O. Pickard-Cambridge, 1900 – Guatemala
• Paratobias F. O. Pickard-Cambridge, 1900 – Honduras, Panama, Mexico
• Pasias Simon, 1895 – Philippines, India
• Pasiasula Roewer, 1942 – Equatorial Guinea
• Phaenopoma Simon, 1895 – South Africa, Senegal, Sierra Leone
• Pharta Thorell, 1891 – Asia
• Pherecydes O. Pickard-Cambridge, 1883 – Africa
• Philodamia Thorell, 1895 – China, Myanmar, Singapore, Bhutan
• Philogaeus Simon, 1895 – Brazil, Chile
• Phireza Simon, 1886 – Brazil
• Phrynarachne Thorell, 1869 – Africa, Asia, New Guinea, Vanuatu, Moluccas
• Physoplatys Simon, 1895 – Paraguay
• Pistius Simon, 1875 – Asia, Russia
• Plastonomus Simon, 1903 – Madagascar
• Platyarachne Keyserling, 1880 – Brazil, French Guiana, Peru
• Platythomisus Doleschall, 1859 – Africa, Asia
• Poecilothomisus Simon, 1895 – Australia
• Porropis L. Koch, 1876 – Angola, Australia, New Guinea
• Prepotelus Simon, 1898 – Mauritius, Réunion
• Psammitis Menge, 1876 – Asia, Europe, Cuba, North America, North Africa
• Pseudamyciaea Simon, 1905 – Indonesia
• Pseudoporrhopis Simon, 1886 – Madagascar
• Pycnaxis Simon, 1895 – Asia
• Pyresthesis Butler, 1880 – Madagascar
• Rangkayo Dhiya'ulhaq & Benjamin, 2025 – Indonesia
• Reinickella Dahl, 1907 – Indonesia
• Rejanellus Lise, 2005 – Cuba, Hispaniola, Puerto Rico
• Rhaebobates Thorell, 1881 – New Guinea
• Runcinia Simon, 1875 – Africa, Asia, Russia, Spain, Australia, New Guinea
• Runcinioides Mello-Leitão, 1929 – Argentina, Brazil, French Guiana
• Saccodomus Rainbow, 1900 – Australia
• Scopticus Simon, 1895 – Indonesia
• Sidymella Strand, 1942 – Australia, New Zealand, South America
• Simorcus Simon, 1895 – Africa, China, Yemen
• Sinothomisus Tang, Yin, Griswold & Peng, 2006 – China
• Smodicinodes Ono, 1993 – China, Malaysia, Thailand
• Smodicinus Simon, 1895 – Africa
• Soelteria Dahl, 1907 – Madagascar
• Spilosynema Tang & Li, 2010 – China
• Spiracme Menge, 1876 – Asia, Eastern Europe, North America
• Stephanopis O. Pickard-Cambridge, 1869 – China, Indonesia, Oceania
• Stephanopoides Keyserling, 1880 – Panama, South America
• Stiphropella Lawrence, 1952 – South Africa
• Stiphropus Gerstaecker, 1873 – Africa, Asia
• Strigoplus Simon, 1886 – China, Indonesia, Malaysia, Myanmar, India
• Strophius Keyserling, 1880 – Mexico to Paraguay
• Sylligma Simon, 1895 – Africa
• Synaemops Mello-Leitão, 1929 – Argentina, Brazil
• Synalus Simon, 1895 – Australia
• Synema Simon, 1864 – Worldwide except Australia
• Tagulinus Simon, 1903 – Vietnam
• Tagulis Simon, 1895 – Africa, Sri Lanka
• Talaus Simon, 1886 – South Africa, Asia
• Tarrocanus Simon, 1895 – Sri Lanka
• Taypaliito Barrion & Litsinger, 1995 – Philippines
• Tharpyna L. Koch, 1874 – Indonesia, India, Australia
• Tharrhalea L. Koch, 1875 – Madagascar, Indonesia, Philippines, Oceania
• Thomisops Karsch, 1879 – Africa, China
• Thomisus Walckenaer, 1805 – Worldwide
• Titidiops Mello-Leitão, 1929 – Brazil
• Titidius Simon, 1895 – South America
• Tmarus Simon, 1875 – Worldwide
• Trichopagis Simon, 1886 – Gabon, Madagascar, South Africa, Guinea
• Ulocymus Simon, 1886 – Argentina, Brazil
• Uraarachne Keyserling, 1880 – South America
• Wechselia Dahl, 1907 – Argentina
• Xysticus C. L. Koch, 1835 – Worldwide
• Zametopina Simon, 1909 – China, Thailand, Vietnam
• Zygometis Simon, 1901 – Thailand to Australia

See also

• Philodromidae, also called crab spiders