AB 1:141-150 (2007)  -  doi:10.3354/ab00014

Clicking for calamari: toothed whales can echolocate squid Loligo pealeii

P. T. Madsen1,2,*, M. Wilson1, M. Johnson2, R. T. Hanlon3, A. Bocconcelli2, N. Aguilar de Soto4, P. L. Tyack2

1Zoophysiology, Department of Biological Sciences, University of Aarhus, Building 1131, 8000 Aarhus C, Denmark
2Woods Hole Oceanographic Institution, and 3Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
4La Laguna University Tenerife, Canary Islands, Spain

ABSTRACT: Squid play an important role in biomass turnover in marine ecosystems and constitute a food source for ~90% of all echolocating toothed whale species. Nonetheless, it has been hypothesized that the soft bodies of squid provide echoes too weak to be detected by toothed whale biosonars, and that only the few hard parts of the squid body may generate significant backscatter. We measured the acoustic backscatter from the common squid Loligo pealeii for signals similar to toothed whale echolocation clicks using an energy detector to mimic the mammalian auditory system. We show that the dorsal target strengths of L. pealeii with mantle lengths between 23 and 26 cm fall in the range from –38 to –44 dB, and that the pen, beak and lenses do not contribute significantly to the backscatter. Thus, the muscular mantle and fins of L. pealeii constitute a sufficient sonar target for individual biosonar detection by toothed whales at ranges between 25 and 325 m, depending on squid size, noise levels, click source levels, and orientation of the ensonified squid. While epipelagic squid must be fast and muscular to catch prey and avoid visual predators, it is hypothesized that some deep-water squid may have adopted passive acoustic crypsis, with a body of low muscle mass and low metabolism that will render them less conspicuous to echolocating predators.


KEY WORDS: Squid · Predator · Prey · Echolocation · Toothed whale · Target strength


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Cite this article as: Madsen PT, Wilson M, Johnson M, Hanlon RT, Bocconcelli A, Aguilar de Soto N, Tyack PL (2007) Clicking for calamari: toothed whales can echolocate squid Loligo pealeii. Aquat Biol 1:141-150

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