These tiny jumping spiders walk like ants to avoid predators – Ars Technica

We usually think of camouflage in nature in terms of body coloration, which enables a species to blend with the background and evade predators. But previous studies have documented locomotor mimicry in some species, such as swallowtail butterflies and net-winged moths, as well as the jumping spider. Myrmarachne formicaria, which mimics the use of limbs and general movement of ants. The latter is an example of perfect mimicry, which is generally assumed to be the most effective in terms of avoiding predators.

But Hua Zeng, an ecologist at Peking University in China, and his colleagues were fascinated by the colorful jumping spider. Syler Collingwoodywhich presents an imperfect simulation, and decided to conduct some laboratory experiments to determine how this might confer protective benefits. They also set out to explore the effectiveness of spider coloration as a camouflage strategy, describing their results in new leaf Published in the journal iScience.

Unlike typical ant-mimicking spiders, which mimic the body color of brown or black ants, S. Collingwoody He has a great body color,” Zeng said. “From a human point of view, they seem to blend in well with plants in their environment, but we wanted to test whether their body coloration serves as camouflage to protect against predators.”

The team first noticed locomotor mimicry while collecting samples from S. Collingwoody from four regions in southern Hainan. The spiders have adapted what the authors call a “stop-and-go” gait pattern similar to ants, which involves extending their first pair of legs up and forward, essentially mimicking an antenna’s antennae. For their experiments, they also collected five different species of ants that share an environment with spiders, as well as a jumping spider that does not mimic ants, Phintelloides versicolor. Finally, they collected samples from two potential predators: one is a type of spider that hunts and eats other spiders, and the other is a praying mantis, a more general predator with a monochromatic visual system.

First, Zeng et al. Analyze trajectory and gait S. Collingwoody And the five types of ants. Here’s how an ant walks:

Here’s how to make a file Syler Collingwoody A jumping spider that walks mimics:

The authors note remarkable similarities, particularly with smaller ant species that were roughly the same size as a spider. In addition to raising their front legs, S. Collingwoody bobbing on their stomachs. “S. Collingwoody Not necessarily a perfect mimic, for its gait and trajectory show great resemblance to the many species of ants,” Zeng said. “Being a general mimic rather than completely mimicking one species of ant can benefit the spiders by allowing them to expand their range if the ant models occupy different habitats.”

Next, they tested the effectiveness of the ant-mimicking defense strategy with a series of anti-predation experiments, exposing both S. Collingwoody And not imitated fi. versicolor For predatory spiders and mantises. Given the selection, predatory spiders were more likely to attack non-mimetic jumping spiders, while the praying mantis attacked both equally. The authors suggest that this is due to size. For a smaller predatory spider, accidentally eating a spiny ant may cause injury, which wouldn’t be a concern for a larger mantis.

As for the bright body colouring S. Collingwoodyzeng et al. performed an analysis of the background color matching of those spiders with the five species of ants and non-mocking spiders, as well as two common plants they favored S. CollingwoodyRed-flowered West Indian jasmine, Fukien tea tree. S. Collingwoody It has been shown to be better hidden from predatory spiders and praying mantises when lurking on jasmine plants rather than tea trees. The authors conclude that this type of jumping spider relies on a combination of imperfect ant mimicry and camouflage coloration to ward off predators.

DOI: iScience, 2023. 10.1016/j.isci.2023.106747 (about DOIs).