Treasures of Oz

Celebrating the Natural Gems of Ozaukee County

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Recreation

Crab Spiders

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Howdy, BugFans,

This stars of this week's episode are not insects, but crab spiders, one of the Bug Lady's favorite critters. They fit into the phylum Arthropoda ("jointed legs") which consists of the Crustaceans, the Insects and the Arachnids. Crab spiders are in the Class Arachnida and are true spiders in the Order Araneae. (In other words, Arachnids are under the big Arthropod "umbrella," which shelters, among others, shrimp, crabs, sowbugs, scorpions, spiders/spider relatives/mites/ticks, millipedes, centipedes and insects. Araneae or true spiders are, in turn, under the Arachnid umbrella which is already under the Arthropod umbrella. Got that?). They have 2 body segments, a cephalothorax and an abdomen, and 8 legs. Crab spiders are so named because they sidle across the flower tops with their front legs held like crab claws. There are about 200 species in the North America. Crab spiders don't make webs.

The flower spider or goldenrod spider (Misumena vatia) is a common species. These come in white and yellow models with the red racing stripes that explain their other name – Red-spotted Crab spider. They can change color from one to the other in about 10 days, so you frequently see white spiders on white flowers and yellow on yellow (but they don't turn purple or rose).

Crab spiders are often successful whether they are camouflaged or not. As you can see from the crab spider holding the dragonfly, they are not shy about tackling prey that is larger than they are, and that the white-on-white thing works pretty well. According to the small but excellent Golden Guide to Spiders and their kin, "They have good eyesight, and when they nab their prey, they hold it up in the air and suck out the juices."

The eggs are placed in a sac which is protected by the female until she dies. The young feed on each other until they are old enough to break out and leave the sac.

 

The “spider-within-a-spider” reminds the BugLady of those Russian Matreshka nesting doll sets. The BugLady has been brainstorming with herself about what is going on here. A spider is shedding its skin? They generally pull themselves out through a split in the abdomen, not through the mouth. A (blush) post-mating bit of cannibalism? The “eatee” looks like the same gender as the “eater.” Simple predation (again, cannibalism)? Tough room!

 

The Bug Lady