Sonar-induced pressure fields in a post-mortem common dolphin

Author Posting. © Acoustical Society of America, 2012. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 131 (2012): 1595-1604, doi:10.1121/1.3675005.Potential physical effects of sonar transmissions on marine mammals were investigated by measuring pressure fields induced in a 119-kg, 211-cm-long, young adult male common dolphin (Delphinus delphis) cadaver. The specimen was instrumented with tourmaline acoustic pressure gauges used as receiving sensors. Gauge implantation near critical tissues was guided by intraoperative, high-resolution, computerized tomography (CT) scanning. Instrumented structures included the melon, nares, ear, thoracic wall, lungs, epaxial muscle, and lower abdomen. The specimen was suspended from a frame equipped with a standard 50.8-mm-diameter spherical transducer used as the acoustic source and additional receiving sensors to monitor the transmitted and external, scattered field. Following immersion, the transducer transmitted pulsed sinusoidal signals at 5, 7, and 10 kHz. Quantitative internal pressure fields are reported for all cases except those in which the gauge failed or no received signal was detected. A full necropsy was performed immediately after the experiment to examine instrumented areas and all major organs. No lesions attributable to acoustic transmissions were found, consistent with the low source level and source-receiver distances.Work supported by NOPP through ONR Grant No. N000140710992. Work at CSI additionally supported by ONR Grant No. N000140811231

Unconventional animal models for traumatic brain injury and chronic traumatic encephalopathy

Traumatic brain injury (TBI) is one of the main causes of death worldwide. It is a complex injury that influences cellular physiology, causes neuronal cell death, and affects molecular pathways in the brain. This in turn can result in sensory, motor, and behavioral alterations that deeply impact the quality of life. Repetitive mild TBI can progress into chronic traumatic encephalopathy (CTE), a neurodegenerative condition linked to severe behavioral changes. While current animal models of TBI and CTE such as rodents, are useful to explore affected pathways, clinical findings therein have rarely translated into clinical applications, possibly because of the many morphofunctional differences between the model animals and humans. It is therefore important to complement these studies with alternative animal models that may better replicate the individuality of human TBI. Comparative studies in animals with naturally evolved brain protection such as bighorn sheep, woodpeckers, and whales, may provide preventive applications in humans. The advantages of an in-depth study of these unconventional animals are threefold. First, to increase knowledge of the often-understudied species in question; second, to improve common animal models based on the study of their extreme counterparts; and finally, to tap into a source of biological inspiration for comparative studies and translational applications in humans

Cetaceans have complex brains for complex cognition

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Where does the air go? Anatomy and functions of the respiratory tract in the humpback whale (Megaptera novaeangliae)

Air is a limited resource under water. Pressure changes during diving and ascent further affect buoyancy and sound production/transmission by changing air volumes, densities, and shapes of air spaces and vibration pathways. This paper will focus on how humpback whales use air, and the respiratory tract adaptations that help overcome these challenges. These highly modified respiratory tract tissues function to shunt air to increase oxygenation for extending breath-hold time, conserve and recycle air, maintain hearing at depth, generate sound for communication and navigation, transmit vibrations to water, mitigate noise, support air spaces from collapsing, regulate chamber volumes, produce bubbles as visual signals, control air release as a tool to trap prey, modify center of gravity, regulate buoyancy, and reduce energy expenditure during locomotion. The humpback whale is able to utilize air in an aquatic environment in ways that allow it to support a wide range of unique behaviors.RÉSUMÉL’air est une ressource limitée sous l'eau. Les changements de pression au cours de la plongée et de la remontée affectent la flottabilité et la production / transmission des sons en changeant les volumes d'air, les densités et les formes des espaces aériens et des voies de vibration. Cet article se penche sur la façon dont les baleines à bosse utilisent l'air ainsi que les adaptations des voies respiratoires qui participent au processus. Les tissus des voies respiratoires sont hautement modifiés et fonctionnent de manière à shunter l’air pour augmenter l'oxygénation afin de prolonger le temps d'apnée, de conserver et de recycler l'air, de maintenir l'audition en profondeur, de générer des sons pour la communication et la navigation, de transmettre des vibrations à l'eau, d'atténuer le bruit, d’empêcher les espaces devant contenir l'air de s'effondrer, de réguler les volumes des chambres, de produire des bulles servant de signaux visuels, de réguler la libération de l'air qui servira d’outil pour piéger des proies, de modifier le centre de gravité, de réguler la flottabilité, et enfin de réduire les dépenses d'énergie lors de la locomotion. La baleine à bosse utilise l'air dans un milieu aquatique de manière à assurer une multitude de comportements uniques

Anatomy of nasal complex in the southern right whale, Eubalaena australis (Cetacea, Mysticeti)

The nasal region of the skull has undergone dramatic changes during the course of cetacean evolution. In particular, mysticetes (baleen whales) conserve the nasal mammalian pattern associated with the secondary function of olfaction, and lack the sound-producing specializations present in odontocetes (toothed whales, dolphins and porpoises). To improve our understanding of the morphology of the nasal region of mysticetes, we investigate the nasal anatomy, osteology and myology of the southern right whale, Eubalaena australis, and make comparisons with other mysticetes. In E. australis external deflection surfaces around the blowholes appear to divert water off the head, and differ in appearance from those observed in balaenopterids, eschrichtiids and cetotherids. In E. australis the blowholes are placed above hypertrophied nasal soft tissues formed by fat and nasal muscles, a pattern also observed in balaenopterids (rorqual mysticetes) and a cetotherid (pygmy right whale, Caperea marginata). Blowhole movements are due to the action of five nasofacial muscles: dilator naris superficialis, dilator naris profundus, depressor alae nasi, constrictor naris, and retractor alae nasi. The dilator naris profundus found in E. australis has not been previously reported in balaenopterids. The other nasofacial muscles have a similar arrangement in balaenopterids, with minor differences. A novel structure, not reported previously in any mysticete, is the presence of a vascular tissue (rete mirabile) covering the lower nasal passage. This vascular tissue could play a role in warming inspired air, or may engorge to accommodate loss of respiratory space volume due to gas compression from increased pressure during diving.Fil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Fernandez, Marta Susana. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fordyce, Ewan. University Of Otago; Nueva ZelandaFil: Reidenberg, Joy S.. Icahn School of Medicine at Mount Sinai; Estados Unido

Two new theoretical roles of the laryngeal sac of humpback whales

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A study of vocal nonlinearities in humpback whale songs: from production mechanisms to acoustic analysis

International audienceAlthough mammalian vocalizations are predominantly harmonically structured, they can exhibit an acoustic complexity with nonlinear vocal sounds, including deterministic chaos and frequency jumps. Such sounds are normative events in mammalian vocalizations, and can be directly traceable to the nonlinear nature of vocal-fold dynamics underlying typical mammalian sound production. In this study, we give qualitative descriptions and quantitative analyses of nonlinearities in the song repertoire of humpback whales from the Ste Marie channel (Madagascar) to provide more insight into the potential communication functions and underlying production mechanisms of these features. A low-dimensional biomechanical modeling of the whale’s U-fold (vocal folds homolog) is used to relate specific vocal mechanisms to nonlinear vocal features. Recordings of living humpback whales were searched for occurrences of vocal nonlinearities (instabilities). Temporal distributions of nonlinearities were assessed within sound units, and between different songs. The anatomical production sources of vocal nonlinearities and the communication context of their occurrences in recordings are discussed. Our results show that vocal nonlinearities may be a communication strategy that conveys information about the whale’s body size and physical fitness, and thus may be an important component of humpback whale songs

Open questions in marine mammal sensory research

Although much research has focused on marine mammal sensory systems over the last several decades, we still lack basic knowledge for many of the species within this diverse group of animals. Our conference workshop allowed all participants to present recent developments in the field and culminated in discussions on current knowledge gaps. This report summarizes open questions regarding marine mammal sensory ecology and will hopefully serve as a platform for future research.Peer ReviewedPostprint (published version