You have those animals that seem to have escaped from a fairytale book. One of them is the Siler collingwoodi, a colorful jumping spider that can pretend to be an ant and disguise itself as a plant. All to prevent it from being eaten.
This special moving camouflage works great to deceive spider-eating spiders. The Siler collingwoodi has mastered the run of an ant and thus ensures that many of its natural enemies drop out. An ant is not a very attractive snack: it is not afraid to fight back and defends itself by biting or stinging and also likes to use poison or acid.
Fantastic color patterns
Chinese researchers wanted to know more about the mimicry of the ant imitator. Which insectivores is he fooling with this and which species see through his tricks? Does he imitate several ant species? And why does he have such fantastic color patterns on his body? “There are quite a few ant-imitating spiders that mimic brown and black ants, but S. collingwoodi has bright body colors,” says lead researcher Hua Zeng from Beijing. “From a human perspective, this spider seems to blend in very well with a plant-filled environment, but we wanted to be more sure about this. That is why we started testing whether the color pattern on its body really serves as camouflage and whether it actually protects the spider against predators.”
The scientists collected all kinds of ant-imitating spiders from four different locations in southern China’s Hainan province and brought them to the lab to study their mimicry techniques. They also took a different species of jumping spider – which does not mimic ants – for comparison, along with five ant species that live in the same area. They studied, among other things, the way in which the spiders move their legs (separately from each other), the speed, acceleration and their preference for straight paths or long curved routes.
Predatory spiders and praying mantises
S. collingwoodi holds its front legs up while walking to mimic the ant’s antennae. At the same time he moves his belly back and forth and raises his legs high, so that he moves like an ant. It most closely resembles the smaller ant species. “S. collingwoodi is not necessarily a perfect mimic of a specific ant species. It mimics several small ants very nicely with its walk and that is why it can work in different ecosystems,” says Zeng.
The researcher decided to subject the spider to a test with two types of predators. Would the colorful spider survive? First he was chased by a jumping spider with color vision and then a praying mantis, which likes everything and cannot distinguish colors. S. collingwoodi was not eaten by the predatory spider – he always went for a jumping spider with no camouflage – but the hungry praying mantis saw right through the bag of tricks and ate the spider again and again. After testing the color camouflage on the West Indian jasmine plant and the Fukien tea plant, it was found that the spiderling was more often overlooked by both the locust and the predatory spider on the jasmine plant.
Miss a leg and the act is over
“We thought beforehand that the results would be about the same for both predators, but nothing could be further from the truth. The ant imitation only worked against the predatory spider, the praying mantis made no distinction between ants and S. collingwoodi, they all died,” explains researcher Zhang. This difference may be explained by the degree of vulnerability of the predators. A predatory spider can be seriously injured by an attack by an ant, while a praying mantis is much larger and is not afraid of a biting ant. “A predatory spider, which is not much bigger than an ant, is much more careful and therefore more selective in choosing its prey. He will S. collingwoodi only attack if he’s pretty sure he’s not dealing with a nasty ant. When the colorful spider is missing a leg and can no longer perform its ant act properly, the predatory spider will eat it raw,” concludes Zhang.