Spying spiders

A team of biologists has discovered that male spiders spy on their rivals during courtship ceremonies, so they can mimic and pinch their most successful dance moves.

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The spiders used in this study were collected from the field. 

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Naive, lab-raised spiders who weren't exposed to male courtship toward females didn't understand the dance and the results were inconclusive. 

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But spiders from the field, who knew what the leg-tapping was all about, behaved as if their on-screen rival was courting a nearby female.

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The researchers put male wolf spiders (Schizocosa ocreata) in front of tiny television sets and made them watch videos of other males perform a sexy, leg-tapping mating dance. 

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The test spiders copied the on-screen males, adjusting the rate of leg-tapping to match and even outperform their rivals.

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Eavesdropping on the communication of others is widespread among animals and often serves as a means of obtaining information, said David Clark, a professor of biology at Alma College and lead author of the study.

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For example, studies of birds, mammals and fish have shown that male bystanders observing male-male contests can learn about the strengths of potential opponents, while female observers may copy the mate choices of others, explains Clark.

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This ’signal matching’ behaviour has only been seen before in vertebrate animals like birds or fish, and suggests that invertebrates like spiders may have more sophisticated behaviours than previously known.

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The closer we look at spiders, the more complex we see they are — their capacity for learning, memory and decision-making is far greater than we ever would have thought.

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Mark Brown - Wired UK