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Misumena vatia

By Mohammad Mahmoud

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)

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)

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). (Comstock, 1965; Kaston and Kaston, 1956; Microsoft Encarta Encyclopedia, 1997)

  • Sexual Dimorphism
  • female larger
  • Range length
    3.0 to 9.0 mm
    0.12 to 0.35 in

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.

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)

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
    • 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. (Anaconda II, 1998; Microsoft Encarta Encyclopedia, 1997)

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).

Contributors

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

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

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.

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