The ultrasonic sonar of bats is extremely well developed, and some species can detect very small objects, perhaps as fine as a spider web, while on the wing. Such an ability draws the admiration of Dr Dedee Woodside, a zoologist at the University of New South Wales, and Dr. Ken Hews-Taylor, a physicist with the CSIRO Division of Applied Physics, who are collaborating in a research project on the ultrasound of bats.