Do Fish "Talk?"
30 December 1997
If you thought that oceans, rivers,
lakes, and streams were worlds of silence, think
again! The waters of the world can be noisy places,
resonating with a variety of sounds. Although fish,
crustaceans, or other invertebrates do not have
vocal cords to enable them to produce sounds, they
use a number of other methods to do so.
Fish use a repertoire of sounds, including grunts,
moans, croaks, and whistles, to convey messages
to each other.
toadfish, one of the most
vocal fish, can
make noises almost as loud as an underground train!
In fact, their sounds are so powerful that, during
wartime, they set off acoustic mines meant to be
triggered by enemy ships.
The loudest of the sonic, or sound-producing, fish "speak"
by vibrating their swim bladders, an air-filled sac in their
abdomen that helps them maintain their balance at varying
depths. Special drumming muscles vibrate the swim bladder
to make loud, low-pitched grunts. The croaker and
among the best known of the sound producing fish, earned
their names by using their swim bladders to emit noises
of varying pitch -- from deep, drum-like thumps to high-pitched
Some fish stridulate, rubbing together the hard parts of
their body such as fins, bones, and spines, to produce grating
or creaking sounds. Fish of the grunt family get their name
from the grunt-like sounds they produce when grinding their
upper and lower pharyngeal teeth. Their swim bladders act
as sounding boxes, resonating and amplifying these sounds.
Even the tiny sea horse makes noises -- by rubbing together
certain bony plates on its head, it makes a sound like the
snapping of fingers.
In addition to the variety of sounds that fish produce,
the sounds themselves may vary in length and pitch and may
be emitted at different intervals. All these variables give
fish several messages it can send. Evidence suggests that
fish, like land animals, use specific sounds to convey different
messages -- to indicate aggressive intent, to signal recognition,
to attract a mate, or to assist in navigation.
Besides a "vocabulary" consisting of grunts,
croaks, clicks, and snaps, fish also use other means of
communication such as chemical odors, or pheromones, and
electrical signals. Some species of fish recognize one another
by odor and associate these odors with position in the local
social hierarchy. Others use pheromones to attract mates
or to signal danger. Electrical signals, small charges emitted
when a muscle contracts, are also used to convey a message
of aggression, courtship, or recognition to other fish.