The snapping shrimp, Alpheus heterochaelis. Courtesy of Department of Applied Physics, University of Twente.

Little research has been done on how marine invertebrates use sound for communication. Snapping shrimp, spiny lobster, and fiddler crabs have been shown to produce sounds for defensive purposes and certain fiddler crabs also appear to produce sounds for courtship. Cleaner shrimp use sound to advertise their cleaning services to reef fish, in particular to predatory fish, as a signal of identity and location.

The snapping shrimp, Alpheus heterochaelis, produces sound in a most interesting and unique way. Upon closure of its enlarged claw, or cheliped, a bubble is formed that cavitates, producing a loud popping sound (see How do marine invertebrates produce sound?). The force of the cavitating bubble is so powerful that it can stun or kill prey items. In the same way, the bubble is used to ward off predators.

Members of the spiny lobster family Palinuridae produce stridulatory sounds via their plectrum and file when the antennae are moved (see How do marine invertebrates produce sound?). Research conducted with European spiny lobsters (Palinurus elephas) in aquariums showed defensive posturing and clicking sounds produced by the spiny lobster in response to predatory behavior by the gray triggerfish (Balistes capriscus). Caribbean spiny lobsters (Panulirus argus) that produced rasp sounds were better able to escape predatory octopus attacks and resist attacks for a longer duration than silenced lobsters.

Fiddler crabs produce sound by striking their enlarged cheliped against other body parts or the seafloor (see How do marine invertebrates produce sound?). These sounds may be used to communicate information to other fiddler crabs about the presence of a nearby predator. Because these sounds are transmitted through the seafloor, they are sensed by mechanoreceptors. This allows fiddler crabs to communicate warning signals to other crabs that are nearby or located in burrows. Male fiddler crabs may also produce sound in this way to court females for reproduction.

A fiddler crab can use its cheliped to produce sound to warn others that a predator is coming. Photo courtesy of Jerry Prezioso.

The cleaner shrimp, Periclimenes longicarpus, claps one pair of claws when reef fish approach, advertising their cleaning services. Cleaner shrimp feed on the parasites found on the skin of reef fish. The hungrier the shrimp is, the more clapping it does. Clapping also acts as protection against predation. By clapping, the cleaner shrimp announces itself as a cleaner; shrimp were shown to clap more often when predatory fish approached.

It is possible that sound production may play a role in the social dynamics of other marine invertebrates but additional research is needed to better understand how marine invertebrates may communicate using sound.