Chapter

Animal Sonar

Volume 156 of the series NATO ASI Science pp 521-534

Natural History Aspects of Marine Mammal Echolocation: Feeding Strategies and Habitat

  • William E. EvansAffiliated withHubbs Marine Research Inst.
  • , Frank T. AwbreyAffiliated withBiology Department, San Diego State University

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Abstract

The state of knowledge of echolocation in marine mammals and cetaceans in particular has been reviewed effectively in recent years (Wood and Evans, 1980; Watkins and Wartzok, 1985). Both of these reviews reveal that most efforts are still directed toward biophysics rather than the natural history, biological, and functional aspects. At the First Animal Sonar Conference in 1966, Donald Griffin and others asked researchers working with cetaceans how echolocation is used in navigation or feeding. Unfortunately 20 years later these two “obvious” uses of this extraordinary capability are still understood mainly by inference. The “Scylla” paradox described in Wood and Evans (1980), indicated that a dolphin deprived of vision can use directional hearing rather than active acoustic scanning to detect and capture moving, avoiding prey. This use of listening (“passive sonar”) has been well studied in bats (Fiedler et al., 1980), but not considered, in print at least, for use by marine mammals. That is changing. Recent tests by Sonafrank, Elsner, and Wartzok (1983) demonstrated that a spotted seal could use vision and listening to find ice holes and to navigate.