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Archive for June 5, 2014

Crab Spider Guarding Egg Sac, not Jumping Spider!

6-5-14 jumping spider2  077Thanks to the sharp eye of Peter Hollinger, a Naturally Curious reader, the spider in this photograph can correctly be identified as a crab spider, possibly in the genus Xysticus, not a jumping spider! The eyes of this crab spider, while impressive, are not nearly as much so as a jumping spider’s. In addition, this crab spider’s four front legs are relatively longer than those of a jumping spider’s. Neither of these types of spiders spins a web to capture prey and both stay with their egg sacs to guard them. Thank you, Peter!

Jumping Spider Guards Egg Sac

6-5-14 jumping spider2  077Spiders protect their eggs by wrapping them up in a sac they make out of silk. Some species (such as garden, or black-and-yellow argiope, spiders) then die, leaving their egg sac to withstand the elements, as well as potential parasites and predators, on their own. As you would guess, these sacs are usually fairly impenetrable. In other species, female spiders survive long enough to guard their eggs until they hatch, or even until the young spiderlings disperse, and these sacs are usually far less tough. In the species where the female protects her eggs, some females carry their egg sacs with them at all times (wolf spiders, nursery web spiders) while others (jumping spiders) simply remain with the sac. Their excellent eyesight and impressive ability to leap many times their body length gives jumping spiders an advantage over any potential predators. (Photo – jumping spider with egg sac)

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