Wed January 9, 2013
Dr. George Poinar, Oregon State University – Ancient Spider Attack
In today’s Academic Minute, Dr. George Poinar of Oregon State University reveals what a piece of amber has to say about the behavior of a long-extinct spider.
George Poinar is an entomologist at Oregon State University in Corvallis, Oregon and a leading authority on amber. He is also the author of numerous books, including The Amber Forest: A Reconstruction of a Vanished World, Life in Amber, and The Quest for Life in Amber. He holds a Ph.D. from Cornell University.
Dr. George Poinar – Ancient Spider Attack
I was amazed when I first saw this piece of Burmese amber with a spider just beginning to feast on a tiny wasp captured in a web. It was obvious that just as the juvenile arachnid was about to secure its catch, a thick, viscid drop of resin covered the entire scene and brought all action to a standstill. It was a disaster for the spider but a stroke of luck for us since it revealed a snapshot of a 100 million year-old drama in a world of dinosaurs and ancient monkey-puzzle forests.
And what a stroke of luck that this particular piece of amber that was dug up by Kachin workers in the northern mountainous portion of Myanmar, passed safely through the hands of craftsmen, collectors and shippers to arrive in one piece at my laboratory in Oregon. Once secure, the rest of the task was easy. Some re-polishing of the amber was needed, then a detailed examination of the contents for later descriptions of the arthropods. Polishing showed that there were two spiders present, the juvenile one attacking the wasp and a male with the remains of another insect wrapped in webbing.
Examining the silk strands of the web under the microscope revealed a series of sticky droplets deposited by the spider to better hold its victims. Finding a juvenile and male spider in the same web indicated that a female had made the web, and then deposited an egg sac, out of which hatched the juvenile spider. So some 100 million years ago, this family of spiders was living together in the same web. They had put their cannibalistic tendencies on hold to cooperate in catching and entangling prey in a mass of silken threads. Such social spiders are still around, mostly in the tropics, but up to now, there was no record of when that behavior originated.