Fossilized Spider Masquerading As Ant Discovered in Colombia

The remains of a prehistoric spider species were recently found, and they were well-preserved. The researchers also noticed that it was still in character -- pretending to be an ant -- to hide from its predecessors.

Fossilized Spider Pretends To Be an Ant

In a new study, paleobiologist George Poinar Junior, who has a courtesy appointment at the Oregon State University College of Science, provides an early account of a recently found species of Myrmarachne colombiana, a spider that mimics ants.

Encased in a block of copal resin, the new species was found in Colombia, South America, as its name implies. Copal fossils can date back up to 3 million years. However, dating the resin would jeopardize the delicate remnants of the spider, making the specimen's actual age unknown.

Its age is not its most intriguing characteristic. Instead, the spider looks like an ant.

Spiders frequently use the act of becoming ants to evade predators. Poinar asserts that there is no evidence of ant-mimicry in Colombian spider populations.

"Ants are particularly good creatures for spiders to pretend to be [because] many animals find ants distasteful or dangerous to eat," Poinar said. Ants are aggressive in their own defense, have a strong bite as well as stinging venom, and can call in dozens of nestmates as allies."

On the other hand, spiders are loners and lack chemical defenses. Hence, they are easily preyed upon by larger spiders, wasps, and birds -- predators who prefer to avoid ants. Therefore, a spider is more likely to be unbothered if it can mimic an ant.

Poinar said it's challenging for spiders to magically transform themselves into ants. However, they could do so by positioning their extra legs to jut out from the front of their body, resembling the ants' antennas. Aside from that, more structures still have to be modified for spiders to resemble ants.

Why Spiders Mimic Ants?

Since ants, in particular, tend to be aggressive, taste awful, and attack in large numbers, it is good to be an ant. Many insects transform themselves to resemble ants for their survival.

However, it was believed that spiders were less able to mimic ants than other insects more closely related to ants due to evolutionary restrictions. However, a recent investigation proved otherwise.

Given their large morphological and evolutionary distance from the model, the researchers predicted that ant-mimicking spiders would be more likely to face constraints on body shape mimicry than ant-mimicking insects.

However, the authors of the paper "Morphological ant mimics: constrained to imperfection?" stated that the most accurate spider mimics are nearly as excellent as the other insect mimics, both dorsally and laterally. Apparently, spiders are good at mimicking ants despite the differences in their body shapes.

The researchers concluded that evolutionary constraints do not explain insects' or spiders' imperfect mimicry. If natural selection applies sufficient pressure, the restrictions might be removed.

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