Acoustical Characteristics of Noise Produced by Snapping Shrimp

Abstract

Some marine animals produce sounds which, under certain conditions, completely dominate the ambient noise in the sea. The snapping shrimp (not to be confused with the edible shrimp) is one of the most widely distributed of these animals; it is frequently less than 3 cm in length and produces the sound by snapping of the claw. Shrimp noise is likely to be found around the world in tropical and sub-tropical waters less than 55 meters deep wherever rock, coral, or other material on the bottom provides interstices in which shrimp thrive. This paper describing the acoustic output of the snapping shrimp (Crangon and Synalpheus) is based upon measurements made off the Southwestern and Southeastern coasts of the United States, the Hawaiian Islands, and several islands in the Southwest Pacific. Over a shrimp bed the noise spectrum is found to be roughly independent of frequency from 2 to 24 kc (the upper limit of measurement), whereas the ambient noise normally present in the deep sea decreases with frequency. There is a broad peak in the shrimp spectrum between 2 and 15 kc. Over a shrimp bed the noise at 20 kc is about 25 db above the ambient noise which accompanies a sea state of 2 (waves less than a meter high, not including swell). For low sea states shrimp noise is appreciable a mile or more from the boundary of the bed. The diurnal variation of shrimp noise is from 2 to 6 db, the noise being greater at night. Single snaps from isolated specimens have been subjected to a Fourier integral analysis which indicates a spectrum comparable to that measured over shrimp beds where the underwater sound consists of a multitude of snaps. A typical peak sound pressure at the distance of a meter from a single shrimp is of the order of 200 dynes/cm2.

Temporal patterns in ambient noise of biological origin from a shallow water temperate reef

“…The most ubiquitous biological component of ambient noise is the snapping shrimp, since it is evident throughout the world in shallow, warm waters, usually in depths of less than 60 m and latitudes less than about 40° (Knudsen et al 1948;Everest et al 1948;Fish 1964). The shrimp responsible belong to the genera Alpheus spp.…”

Anthropogenic and natural sources of ambient noise in the ocean

“…and Synalpheus spp. can be the dominant source of mid-frequency ambient noise (Everest et al 1948). These shrimp have an enlarged claw that produces a water jet with broadband acoustic energy.…”

Evening choruses in the Perth Canyon and their potential link with Myctophidae fishes

“…For example, continental shelf fish choruses have been reported by Knudsen et al (1948), Cato (1978), McCauley and Cato (2000), Parsons et al (2009), Parsons et al (2013), andMcCauley (2012), while invertebrate chorus are also commonly reported (Everest et al, 1948;Fish, 1964;Castle and Kibblewhite, 1975;Radford et al, 2008). Some whale species are now so abundant on their summering breeding grounds that whale calls form seasonal choruses (e.g., Au et al, 2000 for Hawaiian humpbacks or Sirović et al, 2015 for blue and fin whales).…”