How do marine mammals produce sounds?

Mammalian vocalizations are produced by the actions of the larynx, a set of tissues located in the throat. The larynx contains folds of tissue chosen the vocal cords (as well chosen vocal folds), which vibrate as air passes from the lungs into the oral crenel (also called the mouth). The shape and tension of the vocal cords can change to produce different sounds. The sounds can be affected by changes in the shape of the buccal crenel, tongue, and lips.

Structures involved in man speech and voice production. Image credit: National Constitute of Health (NIH)

All species of marine mammals are known to make audio. Marine mammals produce sounds that are used for communication, feeding and navigation. Near all sounds produced by mammals outcome from the move of air through different tissues.

Marine mammals produce vocalizations using mechanisms similar those of land mammals. Pinnipeds (seals and sea lions) take a larynx similar to that of humans. Baleen whales likewise use a larynx to produce sounds. Toothed whales tin produce sounds using their larynx also as specialized air sacs near their blowhole. The larynx is used to produce whistles, while the air sacs are used to produce loftier frequency echolocation signals.

Dolphins produce sounds past passing air through air sacs in their head. Adapted from Dolphin Acoustical Structure (1991) Scheifele, P.One thousand. NUSC TR3080.

Pinnipeds, polar bears, and sea otters produce sound in air and in water and have sound production mechanisms like those of land mammals. Their aeriform vocalizations have been described as barks, cries, grunts, howls, roars, snorts, and squeaks. Underwater vocalizations are described as bell-like sounds, clicks, trills, warbles, and whistles. Sounds are produced by vibration of the vocal folds in the larynx as air passes from the lungs through the larynx, into the throat, and out through the oral fissure. The audio produced by the larynx is modified by changes in the position and shape of the animal'southward buccal crenel, tongue, and lips.

Male California body of water lions, like the i pictured in a higher place, bark profusely when defending their territories. In air, these sounds are produced using the aforementioned mechanisms that humans use. Prototype credit: NOAA.

Odontocetesouthward (toothed whales) produce a wide diverseness of sounds, which include clicks, whistles, and flare-up pulses. Some lower frequency sounds may be produced by the larynx. Most sounds, especially the college frequency sounds, are produced by a circuitous arrangement of air sacs and specialized soft tissues that vibrate as air moves through the narial passages. The sound produced in the air sacs is channeled through the fats of the melon. The melon shape can be modified by the animal to produce a narrow or wide beam of sound.

In contrast to odontocetes, current science indicates that mysticetes use only a larynx for sound production. Inside the larynx is a thick, u-shaped, ridge of tissue (the u-fold, that is homologous to the vocal folds of other mammals). It is located adjacent to the laryngeal sac, a large inflatable "pouch". Baleen whales contract muscles in the throat and breast, causing air to menses between the lungs and the laryngeal sac. Alternating expansion and contraction of the lungs and sac drives air across the u-fold, causing information technology to vibrate and produce sound. Vibrations from the laryngeal sac may propagate through the ventral throat pleats into the surrounding water as audio waves. Changes in the laryngeal sac shape may alter the frequency and/or aamplitude of sounds produced.

Schematic diagram displaying a potential mechanism for audio production in baleen whales. Baleen whales contract muscles in the throat and chest, causing air to flow between the lungs and the laryngeal sac (pinkish tissue in the diagram). Alternate expansion and contraction of the lungs and sac drives air across a u-shaped ridge of tissue, the u-fold (yellow), causing it to vibrate and produce sound. Vibrations from the laryngeal sac (light-green lines) may propagate through the ventral throat pleats into the surrounding water as sound waves. Note: the respiratory tract of the whale is shown red, digestive tract in blue, and associate cartilage in white. Paradigm credit: Dr. Joy Reidenberg. Adjusted from Joy S. Reidenberg and Jeffrey T. Laitman. 2007. Discovery of a low frequency sound source in Mysticeti (baleen whales): Anatomical establishment of a vocal fold homolog. The Anatomical Record. Book 290, Effect 6, pages 745–759.

Marine mammals produce other sounds by slapping parts of their trunk against the surface of the water. Tail or fluke slapping is unremarkably done by cetaceans. Humpback whale tail slaps produce broadband (30-12,000 Hz) sounds. Bottlenose dolphins also use their tails to produce sound. Kerplunks are sounds made when a dolphin lifts its tail and lower body out of the water and crashes it down on the h2o surface. This causes a loud splash and creates a trail of bubbles under the h2o. Other parts of the body that are typically used in producing dissonance in a slapping manner are pectoral flippersouthward and the entire body during lunges and breaches.

Dolphin kerplunk. Courtesy of Connor, Heithaus, Berggren and Miksis.

The sound of humpback whales crashing onto the surface of the water tin be heard underwater. Photo credit: Holly Morin.

Jaw claps are made in a higher place and underwater by forcefully endmost the upper and lower jaws. These types of sound often signal assailment past toothed whales.

Marine mammals brand a variety of sounds that may exist used for audio-visual communication. Bottlenose dolphins make a "bang" sound when they handclapping their jaw. Photo ©Tom Kieckhefer.

Audio clip provided past Jennifer L. Miksis-Olds. Released under Creative Eatables License, not-commercial – no derivs.

References

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