Petra Sierwald studies the fish-eating spiders and their relatives, the nursery-web spiders. Today, these spiders cannot cross the great African Sahara desert. But in the past, when the Saharan area was not as dry, relatives of these spiders' ancestors ranged all the way to southeast Asia. The southeast Asian branch of the family survived and their descendents look still rather similar to their African cousins. By studying the relationships within the fish-eating and nursery-web spiders we discover the history of the main African habitats and how the habitat changes affected the survival or extinction of species within these habitats.

Petra Sierwald was born in Hamburg, Germany, and studied at the University of Hamburg.