Siler collingwoodi is a jumping spider that wears a coat of vibrant and metallic blue, orange, and sometimes red. It also makes impressions and copies the movements of an assortment of ant species.
The jumping spider does not mimic ants for attention – rather the opposite. Ants are aggressively territorial and are known in the insect world for their deadly jaws and their use of venom and other defense strategies. Hundreds of spider species imitate ants to avoid being eaten by predators.
But colorful S. collingwoodi does something distinctive under mimicry. Researchers have found that the jumping spider mimics certain characteristics of several ant species in its habitat. By looking like — but not perfectly imitating — the ants, this makes it what the researchers call an imperfect mimic. But that imperfection is enough to fool one of the jumping spider’s most dangerous predators.
The researchers also found that the spiders can find another layer of protection by blending in with an equally gorgeous plant in their habitat. The findings were published Wednesday in iScience.
When it comes to deterring a predator, many species try “perfect” mimicry because, in theory, appearing almost identical to something scary would increase the chances of survival.
“Most mimicry studies in spiders have focused on the perfect mimics,” said Hua Zeng, a behavioral scientist at Peking University in China and an author of the study. “However, there are also many imperfect mimics, which deserve investigation in terms of their ecological significance.”
While in the field, Dr. Zeng and colleagues found that the S. collingwoodi showed gait patterns similar to those of ants. The spiders even occasionally held up their first pair of legs in a way that looked like an ant holding up its feelers.
The researchers theorized that S. collingwoodi could mimic the movements of more than one ant species, giving themselves more tactics to protect themselves from predators, said Wei Zhang, another author of the study and an evolutionary biologist also at Peking University. . The jumping spider may even be able to expand its habitat in this way.
To test this idea, the researchers collected S. collingwoodi, a non-mimicking jumping spider, and five species of ants from sites on Hainan Island in southern China. Back in the lab, they compared the movement of the ants and spiders and found that S. collingwoodi not only showed pseudo-antennae and moved its abdomen like an ant, but also showed a similar gait, movement pattern and speed to many of the ants. as it went. The other spider did not show these similarities.
The researchers then put the proposed imperfect mimicry of the S. collingwoodi to the test with two of its predators: a mantid species and another jumping spider, Portia labiata. To the mantid, both spiders were fair game. But the predatory spider avoided S. collingwoodi and launched attacks only at the non-mimetic spider, which the researchers interpreted as a sign that ant mimicry worked in some cases.
They also showed that predatory P. labiata would attack an injured S. collingwoodi that was unable to mimic an ant. But in that case there is an alternative explanation. Perhaps, said Ximena Nelson of the University of Canterbury in New Zealand, who was not involved in the study, the S. collingwoodi predator “simply classified the disturbed animals as just that: weakened and possibly easier prey.”
Aside from better understanding imperfect mimicry itself, work like this is important for conservation, said Marta Skowron Volponi, a biologist at the University of Florence in Italy who was not involved in the study.
“The interaction between species is important to study to understand how whole ecosystems function,” said Dr. Skowron Volponi. “To protect an endangered prey species, we need to protect everything associated with it — the predator, the model and the habitat in which it occurs.”