Critter Catalog

What do they look like?

Flowers spiders have short, wide, flat bodies. The first two pairs of legs are larger than the hind legs and held open so that the crab can easily hold its prey. Females are 6 to 9 mm long, males are smaller: 3 to 4 mm. The female is light colored: its back and legs are white or yellow with darker sides, and reddish markings on its abdomen. The male is darker: reddish brown in color with a white spot above the eyes. These colors are variable, and the spiders can change color to match the flower they hide on. Both sexes have small, venomous fangs.

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry
• venomous

• Sexual Dimorphism
• female larger

• Range length

  3.0 to 9.0 mm

  0.12 to 0.35 in

Where do they live?

This species is found in North America and Europe.

• Biogeographic Regions
• nearctic
  • native
• palearctic
  • native

What kind of habitat do they need?

Flower spiders often hides on flowers like trillium, white fleabane, or goldenrod. They also may hunt on the ground or on low structures like fences.

• These animals are found in the following types of habitat
• temperate
• terrestrial

• Terrestrial Biomes
• forest

How do they grow?

Females lay eggs. The spiderlings that hatch out look like mini-adults. As they grow they have to shed their skins, but they do not change their general shape.

How long do they live?

These spiders probably don't live more than two years, but we don't know for certain.

How do they behave?

Crab spiders easily walk sideways and backwards as well as forward.

They do not spin webs, and only use their silk to protect their eggs.

Crab Spiders will change their color to match the background it is hiding on, usually a flower. It sits on a flower or on the ground and waits for its prey to pass and uses its front legs to grasp it. It uses its small fangs to inject its prey with venom, which paralyzes its prey. It does not wrap its prey with silk, but instead holds the prey until it sucks all of its bodily fluids dry.

• Key Behaviors
• diurnal
• motile
• sedentary
• hibernation
• solitary

What do they eat?

Flower spiders feed on invertebrates. They hunt on the ground or on plants, and are able to attack insects larger then themselves because of their venom. Some of the insects crab spiders feed on are butterflies, grasshoppers, and especially flies and bees.

• Primary Diet
• carnivore
  • eats non-insect arthropods

What eats them and how do they avoid being eaten?

The main defense of this species is camouflage. It can bite other invertebrates, but that doesn't help against larger animals. Its fangs are too short and its venom is too weak.

• Known Predators

  • wasps (Hymenoptera)
  • ants (Formicidae)
  • spiders (Araneae)
  • birds (Aves)
  • lizards (Squamata)
  • shrews (Soricidae)

Do they cause problems?

This species has no major negative effect on humans. It occasionally eats honeybees, but is probably not a major enemy of them. The bite of this species is not dangerous to people.

How do they interact with us?

This species sometimes feeds on pest insects such as grasshoppers and flies.

Are they endangered?

This is a common species that is not in need of special protection.

• IUCN Red List

  No special status

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Some more information...

This species is sometimes called "flower spider" and "goldenrod spider". They are the most abundant of flower spiders.

Contributors

Mohammad Mahmoud (author), Fresno City College, Jerry Kirkhart (editor), Fresno City College.

References

Anaconda II, 1998. ""A Mother's Duty"" (On-line). Accessed October 30, 2000 at http://www.anaconda-2.net/tiger/222518.html.

Comstock, J. 1965. The Spider Book. Ithaca, New York: Comstock Publishing Associates.

Kaston, B., E. Kaston. 1956. How To Know The Spiders. Dubuqe, Iowa: Wm. C. Brown Company.

Microsoft Encarta Encyclopedia, 1997. "Crab Spider" (On-line). Accessed October 30, 2000 at http://encarta.msn.com.

Preston-Mafham, R. 1991. The book of spiders and scorpions. New York: Quarto publishing.