Insect Shed Its Exoskeleton to Escape Tree Sap Tomb

Posted on July 19, 2016

Recently shedded exoskeleton in amber fossil

An insect shed its exoskeleton just in time to escape death by oozing tree sap. The photograph above shows the insect's skin embedded in an amber fossil next to a mushroom and a strand of mammalian hair. The Baltic amber fossil is about 50 million years old.

The insect species is extinct today. Researchers believe it was similar to the modern-day walking stick. George Poinar, Jr., a researcher in in the College of Science at Oregon State University, published the study on the fossil. Poinar says the fossil shows signs of the exoskeleton being extremely fresh, such as filaments that would have disappeared if it had not been recently shed before getting covered in tree sap.

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

Poinar also says, "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. It would have shed its skin repeatedly before reaching adulthood, in a short lifespan of a couple months. In this case, the ability to quickly get out of its skin, along with being smart enough to see a problem coming, saved its life."

A research paper on the study was published here in the journal, Fungal Biology. The gilled mushroom is also the first mushroom described in Baltic amber. it is an extinct species.

Photo: George Poinar, Jr., courtesy of Oregon State University

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