1 February 2002
Lobsters can smell danger
Berkeley, Calif.In an effort to teach robots to sense potentially toxic odors underwater, researchers are studying lobsters and crabs.
Because the tasty crustaceans depend on smell to find food or avoid predators, researchers want to know how they pluck those odors from the water swirling around them.
"If you want to build unmanned vehicles or robots to go into toxic sites where you do not want to send a scuba diver, and if you want those robots to locate something by smell, you need to design noses or olfactory antennae for them," said Mimi A. R. Koehl, professor of integrative biology in the College of Letters & Science at the University of California at Berkeley. "We are learning how animal antennae capture odor molecules from the water around them."
Lobsters and other crustaceans sniff by flicking a pair of antennules, dragging them through the water to bring chemosensory hairs on the ends of the antennules into contact with odor molecules.
What researchers want to know is whether the incessant flicking of antennules can pick up fine details of the swirling odors, and how odor molecules penetrate into the brush of chemosensory hairs.
While flicking the antennule of a mechanical lobster, researchers made high-speed, close-up videos of the eddies and filaments in a dye plume to determine whether and how the dye penetrated the array of chemosensory hairs at the antennule's tip.
What they found is that during the downstroke, the lobster pushes the antennule through the water just fast enough for the water and dye to penetrate into the brush of sensory hairs, maintaining much of the detail in the swirls of dye.
On the return stroke, however, it sweeps more slowly, and the water is unable to move between the hairs, allowing the lobster to trap the fine filaments within the brush of hairs until the next rapid downstroke. The lobsters sniff when they flick, and with each flick their antennules capture a detailed map of the swirling odors in the water, Koehl said.