Echolocation signals of the free-ranging Yangtze finless porpoise (<i>Neophocaena phocaenoides asiaeorientialis</i>)

Li, Songhai; Wang, Kexiong; Wang, Ding; Akamatsu, Tomonari

doi:10.1121/1.1882945

Cited by 61 publications

(56 citation statements)

References 13 publications

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“…Odontocetes, specifically, have evolved the use of echolocation, in which a sound is produced by the whale and then that whale listens for a returning echo bouncing off of a target. Echolocation type signals have been reported in over 70 studies in a variety of odontocete species, indicating that the entire clade utilizes echolocation (e.g., review in Au, 1993;Miller et al, 1995;Johnson et al, 2004;Li et al, 2005;Madsen et al, 2005a,b). Evidence for echolocation in dolphins was described early, but not until a study by Norris et al (1961) was the discrimination ability of dolphins using echolocation demonstrated.…”

Section: Echolocation and Sound Sourcesmentioning

confidence: 99%

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Shape analysis of odontocete mandibles: Functional and evolutionary implications

Barroso¹,

Cranford²,

Berta³

2012

Journal of Morphology

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Odontocete mandibles serve multiple functions, including feeding and hearing. One hypothesis is that sound enters the hearing apparatus via the pan bone of the posterior mandibles (Norris, 1968). Another viewpoint, based on computer models, suggests that sound enters primarily through the gular apparatus and the opening created by the absent medial wall of the posterior mandibles. The posterior region of each mandibular ramus has a large, hollow cavity called the mandibular foramen that contains a bulging mandibular fat body (MFB), which terminates on the bony tympanoperiotic complex. The acoustic properties of these fat bodies suggest that they refract sound. This unambiguous link between form and function has catalyzed this current study of mandibular shape. Previous studies have described odontocete mandibles using linear morphometrics and focused on multiple populations within single genera. Geometric Morphometrics (GM) is used to avoid some limitations of linear morphometric studies, using relative 3-D landmark positions instead of lengths. This technique measures shape only, excluding any scaling, rotational, and positional effects.The primary objective of this study is to use GM to quantify mandibular shape across all major lineages of Odontoceti. Eighty-five mandibles, comprised of 40 species, representing all major lineages were included in the shape analysis. Twelve landmarks found on each mandible represent regions of the symphysis and mandibular foramen. The majority of shape variation was found in Jaw Flare and Symphysis Elongation (85.5%). Shape differences in the mandibular foramen also accounts for a portion the total variation (10.9%). The mandibles are an integral component of the sound reception apparatus in toothed whales and the geometry of the mandibular foramen likely plays a role in hearing.The second objective of this study is to assess correlates of hearing and mandibular foramen geometry derived from the GM shape analysis, as well as from linear morphometrics. Echolocation peak frequency (EPF) was used as a measure of sound reception. Odontocete anatomy may emphasize frequencies they need to hear and suppress others in a returning echo during echolocation. Frequencies can be characterized by corresponding wavelengths. Surface area between the four landmarks that represent the mandibular foramen was calculated to assess the relationship between EPF and dimensions of a receiving structure (i.e. mandibular foramen and corresponding MFB). A significant relationship between size of the foramen and EPF was found, suggesting that size of the foramen may limit lower frequencies (longer wavelengths) from propagating through the mandibular fat body.

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Section: Echolocation and Sound Sourcesmentioning

confidence: 99%

“…Norris, 1961;review in Au, 1993;Miller et al, 1995;Johnson et al, 2004;Li et al, 2005;Madsen et al, 2005a,b), suggesting that the entire lineage utilizes echolocation. During echolocation, the animal produces a sound and then listens for a returning echo from the target.…”

Section: Introductionmentioning

confidence: 99%

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Barroso¹,

Cranford²,

Berta³

2012

Journal of Morphology

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“…The porpoise's frequency-dependent general regions of low and high frequency sensitivity are less specific than in the bottlenose dolphin, which shows considerable (near 40 dB) differences across the head (Møhl et al, 1999). A double-acoustic window is intriguing for porpoises as they are considered to mainly produce high frequency echolocation sounds Li et al, 2005), which would be heard best from the front. Dolphins, in contrast, produce a range of sounds including lower frequency whistles and hear lower frequencies well from the side, presumably for evaluating whistle directionality (Lammers and Au, 2003;Popov et al, 2008).…”

Section: Relative Hearingmentioning

confidence: 99%

Hearing pathways in the Yangtze finless porpoise,Neophocaena asiaeorientalis asiaeorientalis

Mooney

Ketten

et al. 2013

Journal of Experimental Biology

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How an animal receives sound may influence its use of sound. While 'jaw hearing' is well supported for odontocetes, work examining how sound is received across the head has been limited to a few representative species. The substantial variation in jaw and head morphology among odontocetes suggests variation in sound reception. Here, we address how a divergent subspecies, the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) hears low-, mid-and high-frequency tones, as well as broadband clicks, comparing sounds presented at different locations across the head. Hearing was measured using auditory evoked potentials (AEPs). Click and tone stimuli (8, 54 and 120 kHz) were presented at nine locations on the head and body using a suctioncup transducer. Threshold differences were compared between frequencies and locations, and referenced to the underlying anatomy using computed tomography (CT) imaging of deceased animals of the same subspecies. The best hearing locations with minimum thresholds were found adjacent to a mandibular fat pad and overlaying the auditory bulla. Mean thresholds were not substantially different at locations from the rostrum tip to the ear (11.6 dB). This contrasts with tests with bottlenose dolphins and beluga whales, in which 30-40 dB threshold differences were found across the animals' heads. Response latencies increased with decreasing response amplitudes, which suggests that latency and sensitivity are interrelated when considering sound reception across the odontocete head. The results suggest that there are differences among odontocetes in the anatomy related to receiving sound, and porpoises may have relatively less acoustic 'shadowing'.

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“…¼ 6.92), and pulse durations ranging from 30 to 122 ls with an average of 68 ls (S.D. ¼ 14.12) (Li et al, 2005a). These narrow-band ultrasonic pulses are quite different from background noise and other artificial sources, and therefore can be easily detected acoustically.…”

Section: Introductionmentioning

confidence: 99%

Passive acoustic survey of Yangtze finless porpoises using a cargo ship as a moving platform

Dong

Wang

et al. 2011

The Journal of the Acoustical Society of America

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In order to periodically investigate the population and distribution of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) in its main distribution range in the Yangtze River, a passive acoustic system deployed on a cargo ship as a moving platform, rather than a dedicated research ship, was developed. A stereo acoustic event data-logger (A-tag) was installed on the cargo ship to passively detect phonating animals. In three surveys carried out in the Yangtze River from Wuhan to Shanghai, an average of 6059 clicks in each survey and 284 porpoises in total were acoustically detected along an 1100-km stretch. The animals were detected frequently in most of the survey range except two "gap sections" with 40 and 60 km lengths, respectively, where no animals were detected in all three surveys. Detected group sizes of the animals in each 120-s time window were not significantly different among the surveys, but the distribution pattern was different and suggested seasonal migration. The cargo ship based passive acoustic survey was effective in detecting phonating animals and can potentially monitor the distribution and population trend over time. Compared to surveys that used dedicated research ships, the present method is more cost effective.

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Echolocation signals of the free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)

Cited by 61 publications

References 13 publications

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Hearing pathways in the Yangtze finless porpoise,Neophocaena asiaeorientalis asiaeorientalis

Passive acoustic survey of Yangtze finless porpoises using a cargo ship as a moving platform

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