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Sleep behaviour

Activity and sleep in dolphins


Arising from: O. Lyamin, J. Pryaslova, V. Lance & J. Siegel Nature 435, 1177 (2005); see also communication from Sekiguchi et al.; Lyamin et al. reply.

According to Lyamin and co-authors, neonate bottlenose dolphins (Tursiops truncatus) almost never sleep, unlike all other mammals that have been studied1. Although we agree that young dolphins never stop and float at the surface, we find that they spend a considerable amount of time asleep while swimming. Our findings therefore call into question the conclusions of Lyamin et al.1.

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Figure 1: Trends in the rest behaviour over different periods of a dolphin calf during its first year.


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Gnone, G., Moriconi, T. & Gambini, G. Activity and sleep in dolphins. Nature 441, E10–E11 (2006).

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