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Confirmation of the occurrence of a second killer whale morphotype in South African waters

Confirmation of the occurrence of a second killer whale morphotype in South African waters Killer whales Orcinus orca occur worldwide in a number of morphotypes that differ in size, pigmentation, acoustic behaviour, food type and genetics – some may indeed warrant subspecific or even specific status. Until recently, all killer whales in South African waters were referred to a single morphotype, Type A, but three individuals (two males and one female) that have stranded since 1969 differ in several respects from other killer whales examined from the region. Adult length is some 1–1.5 m smaller, appendages such as dorsal fin and flippers tend to be relatively larger, and tooth wear is excessive. Although dietary information is scant, one stomach contained the remains of several elasmobranchs, identified from a DNA subsample as blue sharks Prionace glauca, a dietary item that, if habitual, might account for the tooth wear. This morphotype, referred to here as ‘flat-toothed’ and which in several respects resembles the offshore form in the North Pacific and the Type 1 form in the North Atlantic, does not seem to have been recorded previously from the Southern Hemisphere. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png African Journal of Marine Science Taylor & Francis

Confirmation of the occurrence of a second killer whale morphotype in South African waters

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Confirmation of the occurrence of a second killer whale morphotype in South African waters

Abstract

Killer whales Orcinus orca occur worldwide in a number of morphotypes that differ in size, pigmentation, acoustic behaviour, food type and genetics – some may indeed warrant subspecific or even specific status. Until recently, all killer whales in South African waters were referred to a single morphotype, Type A, but three individuals (two males and one female) that have stranded since 1969 differ in several respects from other killer whales examined from the region. Adult length is...
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Publisher
Taylor & Francis
Copyright
Copyright © NISC (Pty) Ltd
ISSN
1814-2338
eISSN
1814-232X
DOI
10.2989/1814232X.2014.923783
Publisher site
See Article on Publisher Site

Abstract

Killer whales Orcinus orca occur worldwide in a number of morphotypes that differ in size, pigmentation, acoustic behaviour, food type and genetics – some may indeed warrant subspecific or even specific status. Until recently, all killer whales in South African waters were referred to a single morphotype, Type A, but three individuals (two males and one female) that have stranded since 1969 differ in several respects from other killer whales examined from the region. Adult length is some 1–1.5 m smaller, appendages such as dorsal fin and flippers tend to be relatively larger, and tooth wear is excessive. Although dietary information is scant, one stomach contained the remains of several elasmobranchs, identified from a DNA subsample as blue sharks Prionace glauca, a dietary item that, if habitual, might account for the tooth wear. This morphotype, referred to here as ‘flat-toothed’ and which in several respects resembles the offshore form in the North Pacific and the Type 1 form in the North Atlantic, does not seem to have been recorded previously from the Southern Hemisphere.

Journal

African Journal of Marine Science – Taylor & Francis

Published: Apr 3, 2014

Keywords: blue shark; dentition; morphometrics; Orcinus orca; prey

References

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