Male frogs croak to attract a female. Females respond with a different and quieter vocalization.
The croaking sound occurs when a frog forces air out of its lungs through its mouth. As the air passes its throat, its larynx (vocal chords) vibrate.
The vocal sacs or pouches distend and blow up like a balloon. The vocal sacs are elastic membranes of skin. Some frogs have the vocal sac under their throat, whereas other frogs have the vocal sac on the corner of their mouth.
The croak is loudest when the frog keeps its mouth and nostrils closed. By forcing air back and forth between their vocal sacs and their lungs, the croak becomes rhythmical.
Each species of frog has a different croaking sound.
Males croak individually or a group of males may croak together in a chorus.
Zoologists think that female frogs prefer males that have a louder, deeper croak.
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM