An 100-million-year-old amber fossil showing the exact moment that a spider begins to attack a wasp has just been discovered by researchers. The scene is perfectly preserved in time, giving a remarkably detailed look into the distant past. This is the only fossil showing a spider attacking prey caught in its web ever found.
It’s an unprecedented fossil, that shows “an action that took place in the Hukawng Valley of Myanmar in the Early Cretaceous between 97-110 million years ago, almost certainly with dinosaurs wandering nearby.”
“Aside from showing the first and only fossil evidence of a spider attacking prey in its web, the piece of amber also contains the body of a male spider in the same web. This provides the oldest evidence of social behavior in spiders, which still exists in some species but is fairly rare. Most spiders have solitary, often cannibalistic lives, and males will not hesitate to attack immature species in the same web.”
“This juvenile spider was going to make a meal out of a tiny parasitic wasp, but never quite got to it,” said George Poinar, Jr., a professor emeritus of zoology at Oregon State University and world expert on insects trapped in amber.
“This was a male wasp that suddenly found itself trapped in a spider web,” Poinar said. “This was the wasp’s worst nightmare, and it never ended. The wasp was watching the spider just as it was about to be attacked, when tree resin flowed over and captured both of them.”
Spiders have been around for a very, very, long time, at least 200 million years. But they are very rare fossils. “The oldest fossil evidence ever found of a spider web is only about 130 million years old. An actual attack such as this between a spider and its prey caught in the web has never before been documented as a fossil, the researchers said.”
“The tree resin that forms amber is renowned for its ability to flow over insects, small plants and other life forms, preserving them in near perfection before it later turns into a semi-precious stone. It often gives scientists a look into the biology of the distant past. This spider, which may have been waiting patiently for hours to capture some prey, was smothered in resin just a split second before its attack.”
“This type of wasp, Poinar said, belongs to a group that is known today to parasitize spider and insect eggs. In that context, the attack by the spider, an orb-weaver, might be considered payback.”
Though the spider and wasp in the amber may look familiar, they both belong to extinct genera. They have been described in great detail in the research paper. One of the most interesting parts of the fossil is its inclusion of at least 15 completely unbroken strands of spider silk, running “through the amber piece, and on some of these the wasp was ensnared.”
“Its large and probably terrified eyes now stare for eternity at its attacker, moving in for the kill.”
The new research was just published in the journal Historical Biology.
Source: Oregon State University
Image Credits: Oregon State University; Orb Weaver via Wikimedia Commons