Clams, Donax variabilis, responded to sound stimuli presented to them
in a laboratory aquarium by jumping out of the sand, lying on the sand
for several seconds, and digging in again. On a beach, clams jump out
of the sand and ride waves, migrating shoreward with the rising tide
and seaward with the falling tide. Parallels between clam behavior on
a beach and that elicited in the laboratory suggest that clams cue on
wave sounds to jump out of the sand. Three aspects of the response to
sound were parallel. (i) Clams were most responsive to low-frequency s
ounds similar to those produced on a beach by waves rolling onto shore
. (ii) Clams were also more responsive to louder sounds; on a beach, c
lams jump preferentially for the largest (loudest) 20% of waves. (iii)
Responsiveness in the laboratory had an endogenous tidal rhythm, with
highest activity occurring at high tide and no activity occurring at
low tide; this rhythm corresponds to the activity of clams on the beac
h from which they were collected. By using sounds to identify large wa
ves, clams can ride selected waves and continuously maintain position
at the sea's edge as the tide floods and ebbs.