Journal of Evolutionary Biochemistry and Physiology

, Volume 45, Issue 1, pp 111–119

States of rest and activity in the Commerson's dolphin Cephalorhynchus commersonii

Authors

  • O. V. Shpak
    • Utrish Dolphinarium Ltd.
  • O. I. Lyamin
    • Utrish Dolphinarium Ltd.
    • Department of PsychiatryUniversity of California
  • P. R. Manger
    • School of Anatomical Sciences, Faculty of Health SciencesUniversity of the Witwatersrand
  • J. M. Siegel
    • Department of PsychiatryUniversity of California
  • L. M. Mukhametov
    • Utrish Dolphinarium Ltd.
Comparative and Ontogenic Physiology

DOI: 10.1134/S0022093009010116

Cite this article as:
Shpak, O.V., Lyamin, O.I., Manger, P.R. et al. J Evol Biochem Phys (2009) 45: 111. doi:10.1134/S0022093009010116

Abstract

The unihemispheric slow-wave sleep, the ability to sleep during swimming with one open eye and the absence of paradoxical sleep in its form observed in all terrestrial mammals are unique features of sleep in cetaceans. Visual observation supplement electrophysiological studies and allow obtaining novel data about sleep of cetaceans. In the present study we examined behavior of 3 adult Commerson's dolphins Cephalorhynchus commersonii kept in the oceanarium Sea World (San Diego, CA, USA). The behavior of the dolphins can be subdivided into 5 swimming types: (1) active swimming marked by variable and irregular trajectory of movement (for 3 dolphins, on average, 35.1 ± 2.7% of the 24-h period) was the active wakefulness; (2) circular swimming was divided into the slow and fast swimming and occupied, on average, 44.4 ± 3.8 and 9.7 ± 0.8% of the 24-h period, respectively; during the circular swimming, dolphins performed from 1 to 6 circular swimming during one respiration pause; (3) quiet chaotic swimming (3.9 ± 1.2%) that occurred at the bottom and was not accompanied by signs of activity; (4) hanging, and (5) slow swimming at the surface (4.1 ± 0.5 and 2.8 ± 0.4%) respectively; the latter two swimming types were accompanied by frequent respiration (hyperventilation). We suggest that the sleep state in Commerson's dolphins occurs predominantly during the circular and quiet swimming. From time to time the dolphins decreased the speed, up to complete stop. Such episodes appeared to be the deepest sleep episodes. In all dolphins, muscle jerks as well erection in male are observed. Most jerks and erections occurred during the circular and quiet chaotic swimming. Thus, Commerson's dolphins, like other studied small cetaceans, are swimming for 24 h per day and they sleep during the swimming. Some muscle jerks that were observed in the dolphins in this study might have been brief episodes of paradoxical sleep.

Key words

unihemispheric sleepparadoxical sleepmuscle jerksrestCommerson's dolphincetaceans

Copyright information

© Pleiades Publishing, Ltd. 2009