Old partners

Natural History, June, 2002 by Stephan Reebs

Organisms preserved in amber (hardened resin from trees) are prized by paleontologists because of the fine details they retain. Such specimens are not rare, but gaining access to them without damaging them can be tricky. It was therefore with trepidation that David Grimaldi, of the American Museum of Natural History, recently broke open several pieces of amber to reach eight primitive termites that had been trapped within the resin 15-20 million years ago, in what is now the Dominican Republic. After dissecting the termites, he gave their guts to Andrew Wier, of the University of Massachusetts, Amherst, to examine under an electron microscope. Grimaldi and Wier were part of a team that was hoping to find the preserved remains of tiny wood-digesting organisms and then to determine how similar they were to microorganisms that Live today in the hindguts of Mastotermes darwiniensis, the only surviving cousin of the amber prisoners.

The researchers were not disappointed. The gut sections revealed not only bits of wood but also numerous protists and bacteria, including large spirochetes. The amazing preservation meant that cell walls, even nuclei and tubules inside cells, were clearly visible. The fossil microbes were strikingly like the modern-day gut residents that break down the wood eaten by M. darwiniensis--a sign of remarkable stability in the evolutionary story of this ancient partnership. ("Spirochete and Protist Symbionts of a Termite [Mostotermes electrodominicus] in Miocene Amber," Proceedings of the National Academy of Sciences 99:3, 2002)

Stephan Reebs is a professor of biology at the Universite de Moncton in New Brunswick, Canada, and the author of' Fish Behavior in the Aquarium and in the Wild (Cornell University Press).