In the humble lobster, scientists may have found a key to understanding the evolution of the calls and sounds made by animal life. Sound studies are notoriously difficult because they depend on biological structures that aren’t always well represented in the fossil record. But answering questions about what kinds of sounds lobsters made hundreds of millions of years ago, and how those sounds have changed over time, may provide insight into questions about behavior and diversity in the animal kingdom at large.
Biologist Sheila Patek of the University of California at Berkeley reasons that if evolutionary history and the study of behavior address, for instance, why the birds of a species sing a particular song, and biomechanics addresses how the bird sings, then all three together address the question of how a structure produces a sound and how that sound has evolved.
If spiny lobsters, aka rock lobsters, don’t seem especially musical, they operate in the right key for Patek. They have a simple structure, lots of variation (45 species), and a fossil record that stretches back for hundreds of millions of years. They also make an obnoxious noise, using flaps that they stroke across rough protuberances under their antennae like violin bows across strings.
Patek began by examining lobster DNA and morphology, drawing the species into an evolutionary tree; then she studied the mechanics of the sound-producing structures; and now she’s working in the field to see how the lobsters use the structures in their environments. As it turns out, they employ the ugly noise as an anti-predator signal, emitting a defensive blast when touched. Exactly how this helps is still a little mysterious: Does it make the predator freeze up long enough for an escape, or does it attract larger predators to scare off the one at hand?
Most of the work of this sort has been on visual or chemical signals, Patek says, while study of auditory signals has been comparatively rare. “So many animals produce anti-predator sounds, but we don’t know a lot about it.” Solving the problem for lobsters might help provide a better theoretical basis for studying the phenomenon on a wider scale.
