These male spiders adopted an unusual strategy to survive sexual cannibalism

The female of the species is deadlier than the male, according to Kipling, but the sentiment would apply to many species of spider. The males in one species of orb-weaving spider have adopted an unusual defense strategy according to a new paper published in the journal Current Biology. They fly through the air in hopes of getting another chance before being eaten.

According to the authors, this species forms colonies in which spiders have individual webs that are linked to form a conglomerate web complex. The communal webs can hold as many as 215 spiders with a male-to-female ratio of 1.5. Female spiders rarely leave their webs if the conglomerate web is destroyed, according to a survey by the team. The males went from web to web in search of mates.

The females were particularly aggressive during the process of sex, which often ended in cannibalism. The male spiders who escaped that fate were able to fly away. The dragline anchored to the female's web was usually produced by male spiders. The male spider jumped off the web after the female spider attacked him.

The team collected spiders from the scenery garden of East Lake in China for their laboratory experiments. They were fed fruit flies twice a week as they matured.

The scientists randomly chose a male and placed him in a container with a female. The female spider ate around 20 fruit flies to make sure she was not hungry. They recorded everything that happened over the next hour, including whether the female spider attacked her mate and whether he survived. The team used each spider once and then released them back into the wild.

Out of 155 successful marriages, the males catapulted after 152 of them. The high-resolution video had a peak speed of 65 cm/s and ranged from about 30 cm/s to almost 90 cm/s. The average speed was 100 m/s 2 and the males spun around at an average of 175 times per second. The three non-catapulting male spiders were killed.

The authors conducted another set of trials to determine whether the male spiders' catapulting behavior was an essential component of the mating process and to confirm that this behavior served to reduce instances of the males being eaten by their mates. They placed a brush close to the dorsum to prevent catapulting. If a male spider wants to avoid being cannibalized by his mate, he needs to catapult.

The team performed trials to determine if the safety line was the cause of the catapulting behavior, by applying a thin layer of super glue to the tips of the spiders' legs. The males were able to catapult.

The team used a scanning electron microscope to look for any special physical structures that could cause such jumping movements. The male spiders can build up pressure on the female spider by folding the joint against it. The male is launched into the air when the joint is released. There was no evidence of a locking mechanism to keep the legs focused during the pressurizing stage.

There are many theories about why sexual cannibalism occurs. We observed that males that could not perform the catapulting were cannibalized by the female. If a male can't perform catapulting, kill it, and if he can do it multiple times, accept his sperm.

Apparently, female spiders can mate up to five times with the same male, although it isn't clear how many times a male spider would need to risk his life to successfully fertilize a female's eggs.

Current Biology is published in 2022. About DOIs is a part of the 10.1016/j.cub.2022.03.051.