A-z - Animals

crab spider

crab spider facts

Physical characteristics of crab spiders

color
  • Brown
  • yellow
  • blue
  • Black
  • white
  • green
  • pink
skin type
Exoskeleton
length
0.16 to 12 inches

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Crab spiders can mimic ants or guano

"They look like little crabs."

Crab spiders are found mainly in the Thomisidae family, but other spiders known as crab spiders can also be found in the families Selenopidae, Sparassidae, and Sicariidae. These spiders include giant crab spiders such as the giant hunter spider.

Crab spiders get their name from the crab-like shape of their legs, which allow them to move backwards, sideways, and forwards. They are also known as flower crab spiders or flower spiders because they can be found on flowers such as roses and goldenrod. They are also found on leaves, under bark, or under leaf litter, waiting for prey.

Sparassoidea hunter spider
Crab spiders get their name from the crab-like shape of their legs, which allow them to move backwards, sideways, and forwards.

©Young Swee Ming/Shutterstock.com

3 Unbelievable Crab Spider Facts!

  • Crab spiders don't spin webs and primarily ambush predators.
  • They can change color to blend in with their surroundings, but this can take a long time.
  • Female crab spiders tend to be larger than males, and in species such as Misumena vatia , females are many times larger than males.

© AZ-Animals.com



Species, types and scientific names

The surname Thomisidae was bestowed by the French scientist Charles Athanase Walckenaer. The name is derived from the Greek word thominx, meaning "rope" or "rope." This is because spiders do not spin webs, but rely on single strands of silk. The female spider lays her eggs in silk sacs or nests she weaves in plants. Females will guard their eggs and even hatchlings until they molt a second time. Mother died soon after. It is likely that she killed and ate the father shortly after mating.

Most female crab spiders stay on plants or other staging areas to wait for prey, while the smaller males roam around.

The family Thomisidae has 2100 species, approximately 175 genera and hundreds of clades. These include the genera Misumena, Bassaniana and Amyciaea .

  • A golden crab spiderMisumena vatia , known as the golden crab spider, is found in Jeonbuk, which is its habitat north of the equator. They are known for their color-changing abilities, although their "resting" colors are white or yellow. These crab spiders can also be pink or light mint green, and can even take on the color of their prey.
  • The Bark Crab Spider – Bassaniana , also known as the Bark Crab Spider, is found in North America, Europe and Asia. They have mottled brown, gray and black colors that camouflage them in the black, brown and gray bark of their waiting prey.
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Crab spiders of the genus Amyciaea have evolved to mimic ants, especially weaver ants.

  • Weaver Ant – This spider tricks the ants into believing it is one of them, then kills and eats it. There are five species of Amyciaea ants, which are found in Oceania, Asia and Africa.

Other genera in the Thomisidae family include:

  • There are about 360 species of Xysticus
  • Thomisops , there are 10 types
  • Loxobates , 10 types
  • There are 14 species of Platythomisus . With the exception of P. jucundus , all Platythomisus spiders are either females or juveniles. All crab spiders in P. jucundus are male.
  • Oxytate , which can turn bright green to camouflage itself in grass or foliage. There are 26 kinds.
  • Boomerangia , which is one of the most recently discovered genera. The genus was discovered in Australia in 2014, and there is currently only one species, B. dimidiata .
  • Phrynarachne spiders mimic bird droppings. There are 30 species in this genus.
Earth Crab Spider
The surname Thomisidae is of Greek origin thominx, meaning "rope" or "rope."

© HWall/Shutterstock.com

appearance

Crab spiders can be identified because their four front legs are longer and thicker than their four rear legs. Like many spiders, they have eight eyes, which often rest on the nodules. They have flattened bodies, two claws, and crab-like legs that allow them to run sideways. This is called a fallback.

Beyond that, crab spiders come in a wide variety of colors and patterns. They come in white and black, brown, sky blue, goldenrod yellow, cherry pink, and leaf green with striped, banded, spotted, and speckled patterns.

Generally, male spiders are between 0.079 and 0.276 inches long, while females are between 0.16 and 0.39 inches long.

Crab spider on white background
Crab spiders can be identified because their four front legs are longer and thicker than their four rear legs.

©iStock.com/GlobalP

History and Evolution

Crab spiders have evolved to ambush their prey, rather than spin webs to catch them. They have adapted to have stronger front legs and to be able to sweep quickly in any direction, and this movement is where they get their name from.

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Some crab spiders have evolved the ability to change body color to mimic whatever flower or plant they inhabit. This adaptation allows them to survive and capture food in nature.

Other crab spiders are able to shape their bodies, such as squashing them, in order to hide in tight places and wait for their victims to ambush them.

Habitat

adult female running crab spider
Crab spiders can be found almost anywhere in the world.

© Vinicius R. Souza/Shutterstock.com

Crab or flower spiders can be found in all but the coldest or driest places around the world. They inhabit under fallen leaves, under the bark of trees, and on plants and flowers. Crab spiders live in tropical, temperate forests, not too dry deserts, and not too cold mountains.

diet

white crab spider on leaf
Crab spiders feed on other insects.

©Peter Yeeles/Shutterstock.com

Crab spiders mainly eat insects that land too close to their hiding place. Because their venom is effective against spiders of their size, they can catch insects much larger than themselves. These insects include crickets, grasshoppers and wasps. Other insects include pests such as aphids, thrips, caterpillars, houseflies, fruit flies, whiteflies, other types of flies and Japanese beetles, but they may also include beneficial insects such as butterflies and bees. Many crab spiders hunt at night, such as the white crab spider Thomisus spectabilis . Others hunt during the day. Due to their small size, crab spiders are often too small to harm humans with their bite or venom.

Some flower spiders, such as Thomisus onustus and the pink crab spider, will eat the nectar and pollen from the flowers they feed on when prey is scarce.

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about the author

heather ross


Heather Ross is a middle school English teacher and mother of 2 people, 2 tuxedo cats and a golden doodle. In between taking the kids to soccer practice and grading homework, she loves reading and writing about all things animals!

Crab Spider FAQs (Frequently Asked Questions)

Are crab spiders dangerous?

Crab spiders are not dangerous to humans, although they are quite venomous for their size. This venom enables them to catch insects much larger than themselves. In the worst cases, a person may be bitten and the pain lasts for several hours, but the bite is not fatal.

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How many legs does a crab spider have?

Like all spiders, crab spiders have eight legs. Interestingly, many spiders, especially males, lose at least one leg during their lifetime. However, losing a leg or two does not affect their ability to hunt.

How do you identify a crab spider?

A crab spider looks like a tiny crab. Its first two pairs of legs are much larger than the other two, and the spider can walk backwards, forwards and sideways.

What is a crab spider?

Crab spiders are a type of arachnid, not an insect, and they primarily belong to the spider family Araneidae, although arachnids known as giant crab spiders belong to other families.

Are crab spiders poisonous to humans?

Crab spiders are venomous, not venomous. Their venom is not dangerous to humans. Most are too small for the fangs to even pierce skin. Giant crab spiders in the family Sparassidae can make people sick, but usually not serious enough to go to the hospital.

Where can I find crab spiders?

Crab spiders are found all over the world in all but the coldest and driest places. Antarctica, for example, does not.

Do crab spiders live in the UK?

Crab spiders do live in the UK. They include Misumena vatia

Is the crab spider any good?

Crab spiders are very good at controlling populations of pests like aphids. That's why seeing crab spiders in the garden is such a good thing.

What does a crab spider look like?

A crab spider looks like a tiny crab. They can be very colorful and hide by changing the color of the plants they feed on. They even change color depending on the insect they eat.

What do crab spiders eat?

Crab spiders eat insects such as grasshoppers, crickets, aphids, whiteflies, wasps, and fruit flies. Unfortunately, they also eat bees, bumblebees, butterflies and moths.

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source
  1. Brandeis University, available here: http://www.bio.brandeis.edu/fieldbio/Spiders_Savransky_Suhd_Brondstatter/Pages/Fam_Thomisidae.html
  2. Merriam-Webster, available here: https://www.merriam-webster.com/dictionary/Thomisidae
  3. University of Kentucky Entomology, available here: https://www.uky.edu/Ag/CritterFiles/casefile/spiders/crab/crab.htm
  4. Bug guide, available here: https://bugguide.net/node/view/87495
  5. Habitat News, available here: http://habitatnews.nus.edu.sg/guidebooks/spiders/text/Amyciaea_lineatipes.htm
  6. Bug guide, available here: https://bugguide.net/node/view/1957/bgimage
  7. Bio Kids, available here: http://www.biokids.umich.edu/critters/Thomisidae/
  8. Wikipedia, available here: https://en.wikipedia.org/wiki/Thomisus_spectabilis
  9. Jungledragon, available here: https://www.jungledragon.com/specie/76/thomisus_onustus.html
  10. Game and Wildlife Conservation Trust, available here: https://www.gwct.org.uk/wildlife/species-of-the-month/2019/crab-spider/