Magazine article Science News

Underage Spiders: Males Show Unexpected Interest in Young Mates

Magazine article Science News

Underage Spiders: Males Show Unexpected Interest in Young Mates

Article excerpt

To the surprise of biologists, a male Australian redback spider will mate with a juvenile female before her reproductive tract has an external opening. The male bites through the immature female's outer coveting and by doing so, protects his own life.

This discovery adds a new twist to a textbook example of extreme mating practices. Until now, biologists had focused on these Latrodectus hasselti males' apparently suicidal sexual behavior with adult females.

While delivering sperm to a mature female, a male typically flips his body and ends up dangling above her fangs, explains Daniela Biaggio of the University of Toronto at Scarborough. Many of these males become lunch, but studies have shown that their sacrifices boost their share of their mates' offspring (SN: 11/13/99, p. 312).

The studies had overlooked an alternative male tactic, Biaggio reported Aug. 14 in Snowbird, Utah, at the annual meeting of the Animal Behavior Society. She's found that given a chance in the lab, males mate non-suicidally with females that haven't yet molted the final time.

Biaggio says that she discovered this alternative mating strategy while observing a practice that's widespread among spider species: adult males hanging around immature females. As Biaggio was arranging her subjects after an experiment, she found one pair entangled. "I freaked,' she says.

Her coauthor Maydianne Andrade, also in Scarborough, says that she was "incredulous" when Biaggio first told her the story. However, they took a new look at female anatomy. About 2 days before a female's final molt, her internal reproductive organs look fully formed. …

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