The rhythm of Love? Male Wolf Spiders Set Elaborate BEATS to Court Females, Study Finds

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From West Side Story to Grease, many hits feature people courting their lovers through song.

Now, a new study has revealed that it’s not just humans who put on shows in the name of love – wolf spiders too.

Researchers from the University of Nebraska have revealed how male spiders trigger a performance of appendage-scratching, twitching abdomens and tapping legs that lasts up to 45 minutes when they encounter a receptive female.

“Females prefer to mate with males who can produce more complex signals than others,” said Noori Choi, lead author of the study.

Researchers from the University of Nebraska have revealed how male spiders trigger a performance of appendage-scratching, twitching abdomens and tapping legs that lasts up to 45 minutes when they encounter a receptive female.

Why do males perform?

Although the reason for these findings is unclear, the researchers suggest that the complexity of the routine may indicate a certain quality in the male that a female would like to see passed on to her offspring.

“Females aren’t necessarily looking for the biggest male, the loudest male, or the loudest male,” Dr. Hebets said.

“But maybe they’re looking for a man who’s really athletic and can coordinate all these different signals into one display.”

Alternatively, females may simply process complex signals better or may simply like new sounds.

“Many studies show that animals prefer novelty, to some extent,” added Dr. Hebets.

“The increasing complexity, especially over time, could almost be seen as a novelty – with the males constantly changing things up to keep the females interested.”

Previous studies have shown that female wolf spiders (Schizocosa stridulans) lay pheromone-laden silk to let nearby males know when she’s in the mood for love.

Males typically taste its silk, before moving their pedipalps – a pair of sensory appendages near the mouth – to hold and eject semen.

Then the male performs his elaborate wing beats, which the female feels rather than hears.

“We wanted to understand why males use complex signals instead of simple signals,” Dr. Choi said.

“Complex signals take a lot of energy and time to produce and can even increase the risk of (attracting) predators.”

To understand why males submit to such elaborate performances, the researchers analyzed 44 performances of male wolf spiders.

The team placed a female spider on filter paper in a soundproof chamber, before introducing a male.

Using a camera and a laser vibrometer, the researchers were able to record the courtship that ensued.

An analysis of the courtship routine revealed that the nine successful males produced more complex vibrational signals than the 35 males who were refused.

Successful males were also more likely to spend time playing for heavier females, which are generally more likely to give birth to and raise a large, healthy group of spiderlings.

As courtship continued, successful males increased the complexity of their routine, indicating that they may be responding to signs of interest from females.

“Signalers pay attention to receptors, they pay attention to their surroundings, and they adapt accordingly,” said Eileen Hebets, who supervised the study.

“We see this in many other animal groups, but people who work with other animal groups are often surprised when they see stories of spiders engaging in these sophisticated behaviors.”

An analysis of the courtship routine found that the nine successful males produced more complex vibration signals than the 35 males who were refused (stock image)

An analysis of the courtship routine found that the nine successful males produced more complex vibration signals than the 35 males who were refused (stock image)

“We’ve found this now in several studies, and it really makes us realize that spiders are just as sophisticated as any other animal when it comes to communication.”

Although the reason for these findings is unclear, the researchers suggest that the complexity of the routine may indicate a certain quality in the male that a female would like to see passed on to her offspring.

“Females aren’t necessarily looking for the biggest male, the loudest male, or the loudest male,” Dr. Hebets said.

“But maybe they’re looking for a man who’s really athletic and can coordinate all these different signals into one display.”

Alternatively, females may simply process complex signals better or may simply like new sounds.

“Many studies show that animals prefer novelty, to some extent,” added Dr. Hebets.

“The increasing complexity, especially over time, could almost be seen as a novelty – with the males constantly changing things up to keep the females interested.”

ARACHNOPHOBIA IS IN OUR DNA

Recent research has affirmed that fear of spiders is a survival trait written into our DNA.

Dating back hundreds of thousands of years, the instinct to avoid arachnids developed as an evolutionary response to a dangerous threat, academics suggest.

This could mean that arachnophobia, one of the most crippling phobias, represents a finely tuned survival instinct.

And it could go back to the beginnings of human evolution in Africa, where spiders with very powerful venom existed millions of years ago.

Study leader Joshua New of Columbia University in New York said: “A number of spider species with potent vertebrate-specific venoms populated Africa long before hominoids and have coexisted for tens of millions of years.

“Humans were at an ongoing, unpredictable, and significant risk of encountering highly venomous spiders in their ancestral environments.”

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