Spider Woman

An Academy researcher is on the trail of one of the most pervasive and successful spiders in the world.

In a small, well-lit office in the Academy's entomology department, spider specialist Diana Silva sits quietly at her microscope, unfazed by the giant, glossy spider clinging to the wall overhead. The subject of a poster titled "Armed and Dangerous" that warns, "aggressive and very fast…runs up walls and glass…in winter, invades houses and moves into old clothes and shoes," this eight-legged outlaw is a member of the tropical wolf spider family (Ctenidae), and one of Silva's enamored study subjects.

Silva, postdoctoral fellow with Academy arachnologist Charles Griswold, is reconstructing the Ctenid family tree, a task of mammoth proportions. Also called wandering spiders because they meander around at night to hunt for insect prey, Ctenids can be found in nearly every nook and cranny of the world, but are most abundant and diverse in the tropical rain forests of Africa and South America.

After identifying more than 200 species from five continents, Silva has found evidence that these successful spiders have had plenty of time to expand their range. Four genera from three distant lands- Gephyroctenus and Caloctenus from northern South America including Silva's home country of Peru, Tsingy from Madagascar, and Diallomus from Sri Lanka-are more closely related to each other than to any other genus on their respective continents, suggesting that Ctenids may have originated some 165 to 130 million years ago, when all these regions were still part of an ancient supercontinent called Gondwana.

Map: Colleen Sudekum