Misumena vatia

Geographic Range

Crab spiders occur all around the world, but Misumena vatia is only found in North America and Europe (Anaconda II 1998; Kaston and Kaston 1956)

• Biogeographic Regions
• nearctic nearctic
  • native native
• palearctic palearctic
  • native native

Habitat

This type of spider is terrestrial and is known to be found on fences, vegetation, and on flowers like trillium, white fleabane, white flower, and goldenrod. (Comstock 1965)

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

Physical Description

M.vatia resembles a crab, for its body is short, wide, and flattened. The first two pairs of legs are larger than the hind legs and held open -- the spider uses them to grab its prey. Females are 6 to 9 mm long, males are smaller: 3 to 4 mm. The female is light colored -- the carapace and legs are white or yellow with darker sides, and sometimes dark reddish markings on the abdomen. The male is darker over all: the carapace is a red to reddish brown with a white spot in the middle ascending to the eye area. The first and second legs are reddish brown, the third and fourth are yellow. The male also has a pair of dorsal and lateral parallel bands of red with a white background. The jaws of this spider are small and slender, and contain venom.

Identification of spiders requires detailed examination of their anatomy. M. vatia has two rows of eyes. The first row or the anterior row is equidistant and are slightly recurved. The second row is also equidistant, but is either more or less recurved. Also the front part of the median ocular area is narrower then behind. There are no teeth in the upper margin of furrow. The hair is simple and is either filiform or rod shaped and are erect. There are no spines on the first and second legs except under tibiae and metatarsi. The genus Misumena is identified within its subfamily Misumeninae by the shape and structure of the clypeus, the front of the cephalothorax (the front body section, where the eyes are).

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

• Sexual Dimorphism
• female larger

Development

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.

Reproduction

In the male of this species the reproductive organ is represented by what's called a "palp organ" which is like an eye droper. Whereas for the female, the complementary organ for the palp is a "epigyne". Like most spiders the palp and the epigyne must be complementary like a key and a lock or mating cannot occur. Misumena vatia females are larger then the males. In spring, after the female is fertilized she spins a cocoon where she lays the eggs. The egg sac is made up of a leaf folded over and is wrapped with a sheet of silk. After she lays the eggs, the female watches over the young and stops eating. She dies after the young hatch, which may take three weeks.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

In spring, after the female is fertilized she spins a cocoon where she lays the eggs. The egg sac is made up of a leaf folded over and is wrapped with a sheet of silk. After she lays the eggs, the female watches over the young and stops eating. She dies after the young hatch, which may take three weeks.

• Parental Investment
• female parental care female parental care

Lifespan/Longevity

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

Behavior

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.

This species will change its 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 immobilizes its prey. It does not wrap its prey with silk but instead holds it's prey until it sucks all of its bodily fluids dry. (Microsoft Encarta Encyclopedia 1997, Comstock 1965)

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

Food Habits

This spider feeds on invertebrates. It hunts on the ground or on vegetation, and it is able to attack larger insects then itself because of its venom. Some of the insects it feeds on are flies, butterflies, grasshoppers, and especially bees. This species often hides on a flower, and ambushes insects that land there. (Microsoft Encarta Encyclopedia 1997, Anaconda II 1998)

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods

Predation

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.

Economic Importance for Humans: Positive

This species sometimes feeds on pest insects such as grasshoppers and flies (Comstock 1965).

Economic Importance for Humans: Negative

The only negative effect that this spider can have is that it sometimes eats honeybees. It is not dangerous to humans.

Conservation Status

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

Other Comments

This species is sometimes called "flower spider" and "goldenrod spider". It is the most abundant of flower spiders (Comstock 1965; Kaston and Kaston 1956).

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

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.