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American Association for the Advancement of Science

Grunt, growl and channel your inner fish

Closeup of the head of a type I male midshipman fish. The many pore-like structures (neuromasts) are part of their lateral line system, while the smaller pearl-like buttons are bioluminescent photophores. [Image courtesy of Margaret A. Marchaterre, Cornell University]

Scowls perpetually, communicates with grunts and growls, spends lots of effort attracting mates and defending territory -- no, it's not the human teenager, it's the toadfish!

These noisy creatures share the ability to vocalize with many other animals, from birds, to frogs, to humans. A new study of these fish suggests that the brain machinery that drives vocalization is extremely primitive, having evolved more than 400 million years ago, with the evolution of bony fish. (This group contains all fish with skeletons made of bone, instead of cartilage, and it includes the ancestors of all vertebrates)

Toadfish use an air-filled sac alled a swim bladder and the muscles attached to it to make a variety of sounds, such as grunts, growls and hums, to attract mates and defend territories.

Andrew Bass of Cornell University and his colleagues have discovered that the network of brain neurons that controls the swim bladder and its muscles has important similarities to the network of neurons responsible for vocalization in other types of animals.

These findings suggests that this brain system, which appears to be common to so many different types of vertebrates, evolved in these animals' common ancestor, the bony fishes.

The study appears in the 18 July issue of the journal Science.