Croakers are called so for the repetitive throbbing or drumming sounds they make. Their croaking mechanism involves the beating of abdominal muscles against the swim bladder. In some species, croaking is used for communication aside from attracting mates. For those species that have year-round croaking ability, the croaks may serve as a low-aggression warning during group feeding, as well as to communicate location in cloudy water. Croaking does make them vulnerable to predation by bottlenose dolphins that are able to find them based on sound. Croakers inhabit coastal waters where the seafloor is muddy or sandy. They largely feed on invertebrates such as crustaceans, molluscs, worms but sometimes small fish as well.