Marine invertebrate communication

How do marine invertebrates communicate using sound?

Some marine invertebrates, predominantly crustaceans, produce sounds that have been shown to facilitate social interactions, such as defense and courtship, and in one case, the acoustic advertisement of a parasite removal opportunity to passing fish. Scientists have given these acoustic emissions a variety of human-auditory biased descriptors such as rumbles, buzzes, honks, raps, drums and clicks to describe them to other humans, but to invertebrates they are acoustic signals that convey critical meaning crucial to surviving in their environments. See the marine invertebrate audio gallery to play audio of these sounds, accompanied visually by frequency spectrograms.

Members of the spiny lobster family Palinuridae produce sound as a defense mechanism. The lobsters generate stridulatory sounds via their plectrum and file when the antennae are moved (Patek 2001). (see How do marine invertebrates produce sound?). Research conducted with European spiny lobsters in aquariums showed defensive posturing and clicking sounds produced by the spiny lobster in response to predatory behavior by the gray triggerfish (Staaterman, Patek, & Claverie 2010). Caribbean spiny lobsters that produced rasp sounds were better able to escape predatory octopus attacks and resist attacks for a longer duration than silent lobsters (Bouwma & Herrnkind 2009).

Semi-terrestrial crabs, such as fiddler crabs and ghost crabs, produce sounds that are transmitted through the air and the sand or mud substrate (see How do marine invertebrates produce sound?). These crabs sense substrate vibration through mechanoreceptors and some species can sense air-borne sound through pressure-sensitive membranes. (see How do marine invertebrates detect sound?).

A fiddler crab uses its cheliped to produce sound to attract females as well as deter predators and other male competitors. Photo courtesy of Jerry Prezioso.

Male fiddler crabs and ghost crabs (see audio gallery) are known to use a combination of visual and auditory or vibrational signalling behaviours in their social interactions – for both courtship displays and burrow territorial defense. They produce rapping or honking sounds as one way to court females for reproduction (Salmon 1983; Clayton 2008). During the day, male fiddler crabs will wave with their enlarged claw to attract females to their burrow. Once a female crab approaches, the male switches to sound production from within or just outside of his burrow. To produce sound, the male crabs will strike the substrate with the lower base of their enlarged claw, drum on the substrate with both claws, and/or tap the ground with their walking legs. Sound production can last several minutes (Mulder et al, 2025).

Scientists have further observed that male crabs “pay attention” to neighboring males that are drumming or rapping. If one male begins to produce sound vigorously, other males may respond by also increasing the speed and loudness of their sound production. Additionally, if one male is silent and a neighboring male begins to produce sound vigorously, the previously silent male will often join in. Male crabs will also alter their rapping rate to avoid overlap with other males. A male crab that avoids overlap between his raps and that of a neighboring male will present a distinct signal that can be better detected by a receptive female. Some species of fiddler crab produce sound lasting up to several hours by rapping outside their burrows.

Although semi-terrestrial crabs produce sound primarily for courtship, they also can send warning signals to alert other crabs to the presence of a nearby predator and use sound during agonistic interactions with other male crabs (for example mangrove crabs Boon et al. 2001).

Cleaner shrimps identify themselves as a “cleaner” and advertise their services to reef fish by clapping their claws (chelipeds). The hungrier the shrimp, the more clapping it does. In this video, one can watch a cleaner shrimp (small, transparent animal at center) clap/signal to reef fish swimming nearby.
Video by Lucille Chapuis, University of Western Australia.

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

Some marine invertebrates communicate with sound for purposes other than defense and courtship. Cleaner shrimp feed on parasites found on the skin, and  in the mouths and gills of reef fish. The cleaner shrimp typically establishes ‘cleaning stations’ on a coral reef. Fish identify cleaner shrimp based on their cleaning station and visual displays, and some shrimp will also provide acoustic signals by clapping their claws when reef fish approach. Clapping also has been observed to occur in the presence of predators; shrimp were shown to clap more often when predatory fish approached (Chapuis and Bshary 2010).

Snapping shrimp, or pistol shrimp, produce one of the most intense biotic underwater sound pressure levels ever recorded (Jakobsen et al. 2021) with the rapid closure of their claws producing a cavitation bubble that collapses to produce a loud snap (Veslius et al., 2000), with which they stun their prey and ward off predators. (see How do marine invertebrates produce sound?).  When recorded at the environmental level, snapping shrimp populations are responsible for the majority of sounds produced in many nearshore environments (including but not limited to bays, harbors, oyster reefs, coral reefs, estuaries, mangroves).

Video: On the Sound of Snapping Shrimp


(created by scientific authors Veslius et al., 2000)

At the environmental level, snapping shrimp sound production is known to vary by time of day, tidal and lunar cycle and season. Snapping shrimp noise levels measured at nighttime were higher than those during the day by 3–6 dB  (Johnson et al., 1947; Everest et al., 1948; Lammers et al., 2008), with increased snapping rates in a given area at sunrise and sunset. This acoustically active period is commonly referred to as a dawn and dusk “chorus” – when many crustaceans and fish are acoustically active. One study showed that the number of snaps correlated with seasons (Bohnenstiehl et al., 2016). Other studies show that snapping rates can be correlated with tidal patterns (Song et al., 2023), and vary with diel and lunar cycles, as well as with temperature and light levels (Lillis and Mooney 2018).

Even with advanced knowledge of the mechanisms of snapping shrimp sound production and population acoustics over space and time, there is still much to learn about how snapping shrimp are acoustically interacting with each other and with other animals in their specific environments. For instance, scientists studying sponge-dwelling snapping shrimp observed ‘coordinated snapping’ behaviors among related conspecifics that successfully repelled invading shrimp (Tóth & Duffy 2005) – a report of a collective group response. This study provides a glimpse into what targeted future research in individual-to-population level behaviors may reveal about how snapping shrimp, in all their various habitats and climes, use acoustics in their daily lives.

Additional Links on DOSITS

Additional Resources

  • Sebeok, T., ed, 1977, “How Animals Communicate.” Indian University Press, Bloomington, 305-307.
  • Mooney, T.A., Roberts, L., McCravy, K.W., & Thomas, J.A. (2025). Invertebrates Other than Insects. In: Erbe, C., Thomas, J.A. (eds) Exploring Animal Behavior Through Sound: Volume 2. Springer, Cham. https://doi.org/10.1007/978-3-031-83460-8_1

References