Spiders can pretend to be many things, but have you ever seen a spider that pretends to be an ant? Meet Siler collingwoodi, a colorful jumping spider found in the jungles of China and Japan. These little spiders are among the favorite prey of praying mantises and other big spiders. However, nature has given them two uncanny skills to defend themselves; their abilities to walk like ants and to camouflage with flowers of plants like jasmine.
Spider mimicry
Researchers at Peking University (PKU) in China recently published a study that reveals interesting details about these two strange abilities of S. collingwoodi. Scientists already know about the defense mechanism used by these spiders, what they don’t know is the ant species whose walking style the spider mimics. Moreover, there are some other spider species as well that camouflage with plants, but S. collingwoodi does so very differently from them.
The new study provides answers to many such questions about the spider that were never explored before. Hua Zeng, the lead author of the study, and an ecologist at PKU said:
“Unlike typical ant-mimicking spiders that mimic the brown or black body color of ants, S. collingwoodi has brilliant body coloration. From a human’s perspective, it seems to blend well with plants in its environment, but we wanted to test whether their body coloration served as camouflage to protect against predators.”
The study authors conducted a series of experiments in which they compared the walking patterns of four S. collingwoodi spiders with that of another jumping spider that didn’t mimic ant activity. They also observed the walking styles of five different types of wild ants that lived in the same habitat as that of S. collingwoodi, and tried to find similarities.
After carefully examining how the spiders used their limbs to walk, run, jump, and change directions, the researchers note, “Rather than jumping like most jumping spiders, S. collingwoodi move like ants: by raising their front legs to mimic an ant’s antennae, bobbing their abdomens, and lifting their legs to walk in an ant-like manner. Of the five ant species, the spiders’ walking style most closely resembled the three smaller ant species, who are also closer to it in size.”
The results also highlight that S. collingwoodi doesn’t follow the walking style of one particular ant but mimics multiple wild ant species. But how does this mimicry protect the spider?
Most animals and big insects don’t prefer to eat wild ants and stay away from them. This is because their bodies are covered with spines and contain poisonous chemicals. Moreover, wild ants are also known to defend themselves by attacking in large numbers. S. collingwoodi‘s ant-like gait makes it appear to predators as if it’s a wild ant, and as a result many times the predators leave the spider alone.
But what about the funky look?
The ant-mimicking spiders have beautiful bright-colored shells that allow them to blend with the surrounding environment. The researchers performed a series of interesting experiments to check the success rate of this defense mechanism. They placed the spiders in two different backgrounds that matched the Fukien tea tree and West Indian Jasmine plants respectively.
Next, they introduced predators like the praying mantis (Gonypeta brunneri) and Portia labiata (medium-sized jumping spiders that love eating S. collingwoodi) near the setup where the little spiders were walking. Interestingly, the Fukien tea tree and jasmine plants are both natural habitats of the spiders but during the experiment, predators found it more difficult to spot the spiders on the jasmine plant background.
They also noticed that if an S. collingwoodi spider hurts one of its limbs, it’s not able to accurately mimic the walking style of ants. However, the researchers didn’t just stop there, they tested the spiders with other jumping spiders that didn’t mimic ant-walking against the predators.
“When the predators were given the choice of the ant-mimicking spider and the other jumping spider, the predatory spider was more likely to attack the non-mimic; out of 17 trials, the spider launched 5 attacks, all of which were towards the non-mimic. Praying mantises, however, attacked both prey species with equal alacrity,” the researchers note.
All these findings suggest the significant role that mimicry and camouflage play in ensuring the survival of this spider. Hopefully, this research work will also allow scientists to design better conservation strategies for these lovely eye-catching spiders.
The study is published in the journal iScience.
