Sound carries far more information. Dolphins and whales navigate and communicate with a complicated system of sonar and signals.
Nuclear submarines have elaborate listening systems.
Nobody knows, but a team at the New England Aquarium in Boston is trying to find out. Instead, they're working at the most basic level, trying to learn exactly which frequencies a turtle can hear. The results could help in the conservation of the six sea turtle species, all of which are classified as endangered or threatened. For the past year or so, the aquarians have been trying to train Myrtle, a fifty-something green sea turtle, to respond reliably to sounds in her environment. Green sea turtles live in the tropics worldwide.