Misumena vatia
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 Goldenrod crab spider with prey
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| Misumena vatia (Clerck, 1757) |
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Araneus vatius |
Misumena vatia is a species of crab spider with holarctic distribution. In North America, where it the largest and most well-known flower spider, it is called the Goldenrod crab spider, because it is commonly found hunting in Goldenrod sprays in the autumn.
Females can grow up to 10mm (without legs), males reach 5mm at most.
Young females in the early summer may be quite small and easily overlooked. These spiders may be yellow or white, depending on the flower in which they are hunting. Especially younger females, which may hunt on a variety of flowers such as daisies and sunflowers, may change color "at will" (aggressive mimicry). Older females require large amounts of relatively large prey to produce the best possible clutch of eggs. They are, therefore, in North America most commonly found in Goldenrod (Solidago sp.), a bright yellow flower which attracts large numbers of insects, especially in autumn. It is often very hard even for a searching human to recognize one of these spiders on a yellow flower.
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[edit] Reproduction
The much smaller males scamper from flower to flower in search of females and are often seen missing one or more of their legs. This may be due to either near-misses by predators such as birds or to fighting with other males.
When it finds a female, it climbs over her head over her opisthosoma onto her underside, where it will insert its pedipalps to inseminate her.
The young will reach a size of about 5mm until autumn and spend the winter on the ground. They molt for the last time in May of the next year.
[edit] Color change
The color change is made possible by secreting a liquid yellow pigment into the outer cell layer of the body. On a white base, this pigment is transported into lower layers, so that inner glands, filled with white guanin, become visible. If the spider dwells longer on a white plant, the yellow pigment is often excreted. It will then take the spider much longer to change to yellow, because it will have to produce the yellow pigment first. The color change is induced by visual feedback; spiders with painted eyes were found to have lost this ability.
The color change from white to yellow takes between 10 to 25 days, the reverse about six days. The yellow pigments have been identified as kynurenine and 3-hydroxykynurenine[1]
[edit] See also
[edit] References
- ^ Oxford, G.S. & Gillespie, R.G. (1998). Evolution and Ecology of Spider Coloration. Annual Review of Entomology 43:619-643. DOI:10.1146/annurev.ento.43.1.619
[edit] External links
- Pictures of M. vatia on BugGuide.net
- Great pictures of male
- Pictures of M. vatia (free for noncommercial use) (another one)
