SHARKS were always thought to be long-sighted, but researchers who gave them
an eye test found they can focus correctly on both near and distant objects.
Testing a shark’s eyesight usually involves restraining it, holding
different lenses up to its eyes and watching their response. But by reflecting
infrared light off the back of their eyes using a camera, Bob Hueter of Mote
Marine Laboratory in Sarasota, Florida, and his colleagues have shown that
free-swimming lemon sharks can focus on near and distant targets (Vision
Research, vol 41, p 1885).
Restraining sharks may have relaxed their eye muscles, making…
