( Whip spiders considered by many to be ...)A rarity among arachnids, whip spiders have a sociable family life

In two species of whip spiders, or amblypygids, mothers caress their young with long feelers, siblings stick together until they reach sexual maturity, and all mix in social groups. This is surprising behavior for these arachnids long-thought to be purely aggressive and anti-social, according to a Cornell researcher.

Social behavior is extremely rare in arachnids, a class that includes spiders, amblypygids, scorpions and mites, among others; only 76 (or less than 0.1 percent) out of the 93,000 known arachnid species have been observed living in social groups. The research, appearing in recent issues of both the Journal of Arachnology and Natural History magazine, marks the first time social behavior has been reported in amblypygids.

"This was the best example I had ever seen of friendly behavior in an arachnid," said Linda Rayor, senior research associate in entomology and the lead author of both articles. Rayor describes in the articles how mothers habitually stroke their offspring with their long, thin whiplike front legs and how the siblings congregate in social groups.

"I was amazed at how incredibly interactive the groups are," said Rayor. "They are in constant tactile contact with one another. They are constantly exploring one another and interacting with their siblings."

Scientists have long thought these creatures were solitary and cannibalistic predators, as past studies have focused mainly on the adult's dramatic courtship and fighting behaviors. Rayor believes that because young amblypygids slip easily into tight crevasses and their coloring matches their backgrounds, the social behavior of the youngsters has been missed in the wild.

Rayor's research on two species in captivity (the dime-sized Phrynus marginemaculatus from Florida and a much larger Damon diadema from Tanzania) suggests th
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Source:Cornell University News Service