Sounds associated with feeding may be produced intentionally or unintentionally. The most common sounds associated with feeding are simply a result of chewing and ingesting food items. The diets of many fishes contain hard parts, such as the skeletons of crustaceans and fishes, and the calcium carbonate of corals. Crunching sounds are produced when the fishes' teeth rub against these hard objects. Even fishes that eat plants produce sounds in this way. This form of sound production is an example of stridulation. Sounds produced while feeding may be detected by other fishes and used as cues to indicate feeding opportunities. These sounds can be quite obvious even to humans. Queen parrotfish (Scarus vetula) biting chunks of coral reefs are often heard by divers.

The Queen parrotfish makes a "crunch" sound while feeding on coral. Photo courtesy of Alfredo Cavalho Filho, alfie@telnet.com.br

Hydrodynamic sounds produced by fishes may also provide information on feeding opportunities. For example, large schools of fish such as jacks (family Carangidae) or ladyfish (family Elopidae) often begin voracious feeding frenzies when they locate areas abundant in prey items. During these feeding frenzies, rapid changes in swimming velocity produce low frequency hydrodynamic sounds that may attract other predators to the area. Intentionally produced sounds that may be used to deter other predators and competitors have also been observed during feeding frenzies. In another example it has been hypothesized that low frequency hydrodynamic sounds produced by a wounded or struggling fish attract sharks. A fisherman using a live fish as bait is trying to take advantage of this possibility.

During a feeding frenzy, sound may be produced by fish to protect themselves and their food. Low frequency hydrodynamic sounds are also generated by the bodies of fish due to rapid changes in swimming direction and velocity. Photo courtesy of Christie and Wiley Long, http://www.longstrangetrip.com

In some cases sounds may be intentionally produced during competition over resources such as food. Amorim and Hawkins (2000) described in detail the sounds made by streaked gurnards (Trigloporus lastoviza) while competing for food. Aggressive chasing behavior accompanied by low growling sounds were emitted by these fish when competing for prey items. Similar growling sounds are also produced by rockfish species (family Scorpaenidae) during competitive interactions.

References
• Amorim, M.C.P. and Hawkins, A.D. 2000. Growling for food: acoustic emissions during competitive feeding of the streaked gurnard. Journal of Fish Biology 57: 895-907.
• Myrberg, A.A., Jr., Gordon, C.R., and Klimley, A.P. 1976. Attraction of free ranging sharks by low frequency sound, with comments on its biological significance. Pages 205-228 in Schuijf, A. and Hawkins, A.D. (eds.). Sound Reception in Fishes. Elsevier Scientific Publishing Company, New York.
• Tavolga, W. N. 1977. Sound Production in Fishes. Benchmark Papers in Animal Behavior V.9. Dowden, Hutchinson & Ross, Inc.

For more information on how other marine animals use sound when feeding, use the following links:
Marine Mammals	Fish	Invertebrates