Acoustic Communication and Possible Use of Echolocation by the Hippopotamus (Hippopotamus amphibius)
Item
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Title
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Acoustic Communication and Possible Use of Echolocation by the Hippopotamus (Hippopotamus amphibius)
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Identifier
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d_2009_2013:b5b75509fb6c:11074
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identifier
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11409
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Creator
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Maust-Mohl, Maria,
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Contributor
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Diana Reiss
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Date
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2011
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Language
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English
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Publisher
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City University of New York.
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Subject
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Behavioral sciences | Zoology
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Abstract
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Recent genetic, molecular, and fossil evidence provide support of a hippo-whale clade and suggest their ancestors may have been semi-aquatic. This evidence raises questions about the evolution and adaptation of the common hippopotamus (Hippopotamus amphibius) to an aquatic environment. This study sought to examine the amphibious nature of the hippopotamus through investigations of their adaptations, communication, and sensory systems to determine possible connections with their close aquatic relatives, the cetaceans. Audio and video recordings were collected of male and female hippos at Disney's Animal KingdomRTM, where the zoological context offered unique and controlled conditions to conduct observational and experimental studies. The goals of this research were to review the literature on the evolution and adaptations of hippos, which revealed adaptations that may represent shared derived characters from the common ancestor of hippos and cetaceans. Measurements and descriptions obtained from a recent dissection of an adult female hippo indicated that their vocal folds were similar in orientation and shape to baleen whales and the fold on their neck did not contain fatty tissue. Research investigating the acoustic and behavioral repertoires of hippos demonstrated three main categories of acoustic signals (burst of air, tonal, and pulsed) that were similar to those recorded from wild hippos. The acoustic parameters and behavioral contexts were reported and analyzed, demonstrating 11 distinct signal types within the three categories. The occurrence of acoustic and behavioral signals during social interactions suggests they mediate dominance and submissive interactions. Observational and experimental approaches used to investigate the potential use of echo-ranging by hippos provided three lines of evidence that support this hypothesis. First, two male hippos produced click trains in non-social contexts while searching for carrot bundles underwater. Second, click trains were associated with obtaining carrot bundles and most were produced prior to chewing. Third, the frequency parameters of clicks could be used to detect objects the size of the carrot bundles underwater. The click trains of hippos resembled clicks produced by young dolphins and may be used to detect larger objects, conspecifics, or for navigation in the murky waters they inhabit.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Psychology
