Thursday, March 22, 2007

Spiders Get Cuddly

Not all spiders eat other after sex. In fact, new research shows that at least two species of 'whip spider' are downright affectionate towards each other and their siblings. They cuddle, they caress, they nurture their young. Life for 'teenage' whip spiders is, however, more dangerous, and more aggressive.

This report from Live Science explores the touchy-feely side of arachnids :

Social behavior is extremely rare in arachnids, a group of critters typically defined by their aggression, clever hunting methods and even predatory cannibalism.

"This was the best example I had ever seen of friendly behavior in an arachnid," said lead study author Linda Rayor, a Cornell University entomologist.

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

Rayor and her colleagues studied two whip-spider species, dime-sized spiders common in Florida, called Phrynus marginemaculatus, and a much larger species found in forests and caves in Tanzania and Kenya, Damon diadema.

Observed in glass houses, the two arachnid families were often seen engaging in sibling-sibling and mother-baby interactions. In one experiment, the siblings were removed from a familiar cage and placed randomly into a large unfamiliar cage. Within minutes, they gathered back together.

Mothers of both species nurtured their young. Often, the mama whip spider would sit in the middle of her offspring and slowly stroke their bodies and whips with her own feelers.

Whereas amicable behavior continued into adulthood for P. marginemaculatus, teen life was rougher for D. diadema. After these arachnids reached sexual maturity, the scientists found evidence they had outgrown their cuddly behavior: adolescent spiders had missing or injured legs attributable to fighting.

Past studies have focused on the more visible features, such as the adult's courtship displays and fighting behaviors, so scientists had assumed the creatures were solitary and cannibalistic predators.

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