Baltic amber records insect escape story

Researchers have uncovered the exoskeleton of an insect in a piece of Baltic amber about 50 million years old, suggesting that the insect was frightened out of its skin as it was about to become forever entombed by oozing tree sap.

The findings, published in the recent issue of Fungal Biology by George Poinar, Jr., a researcher in the College of Science at Oregon State University (OSU) in the U.S. Pacific Northwest and an international expert in ancient life forms found in amber, also involved the first mushroom that has ever been found in Baltic amber.

"From what we can see in this fossil, a tiny mushroom was bitten off, probably by a rodent, at the base of a tree," Poinar said.

"An insect, similar to a walking stick, was probably also trying to feed on the mushroom. It appears to have immediately jumped out of its skin and escaped, just as tree sap flowed over the remaining exoskeleton and a hair left behind by the fleeing rodent."

Plants, insects and other material found in amber deposits offer details about ancient ecosystems, Poinar was quoted as saying by an OSU news release.

But on rare occasions such as this, as the amber came from near the Baltic Sea in what is now Germany, Poland, Russia and Scandinavia, they also show the interactions and ecology between different life forms and are invaluable in helping scientists to reconstruct the nature of ecosystems in the distant past.

The amber was formed, beginning as a viscous tree sap, in a large subtropical coniferous forest across much of northern Europe that lasted about 10 million years.

The exoskeleton seen in the amber is extremely fresh and shows filaments that would have disappeared if it had been shed very long before being covered by amber, Poinar said. The insect species is now extinct, as is the mushroom in the fossil.

In a climate much warmer than exists there today, the early angiosperms, or flowering plants, were starting to displace the gymnosperms, or cone-bearing evergreens that had previously been dominant.

"The tiny insect in this fossil was a phasmid, one of the kinds of insects that uses its shape to resemble sticks or leaves as a type of camouflage," Poinar said. "It would have shed its skin repeatedly before reaching adulthood, in a short lifespan of a couple months."

"In this case," he noted, "the ability to quickly get out of its skin, along with being smart enough to see a problem coming, saved its life." Endit