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Animals at the extremes: Hibernation and torpor

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Hibernation is an ingenious adaptation that some animals employ to survive difficult conditions in winter. This free course, Animals at the extremes: Hibernation and torpor, examines the differences between hibernation and torpor, and discusses the characteristic signs of hibernation behaviour. It explores the triggers that bring on hibernation, and whether internal signals or external season cues are predominant. It also examines the physiological adaptations that occur in hibernating animals.

After studying this course, you should be able to:

  • define and use, or recognise definitions and applications of, each of the bold terms
  • give definitions of the terms ‘hibernation’, ‘torpor’ and ‘adaptive hypothermia’, and the three physiological processes that underlie them
  • give examples of the diversity of the major groups of mammals and birds that contain hibernating species
  • describe the physiological changes occurring during entry to hibernation and at least three of the cues that may trigger entry
  • present evidence to show that hibernating mammals and birds retain physiological control of their Tb.

By: The Open University

  • Duration 14 hours
  • Updated Thursday 24th March 2016
  • Intermediate level
  • Posted under Natural History
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The content acknowledged below is Proprietary (see terms and conditions [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] ) and is used under licence.

Grateful acknowledgement is made to the following sources for permission to reproduce material in this course:

Course image: Mike Boswell in Flickr made available under Creative Commons Attribution 2.0 Licence.

Figure 2 Michael and Diane Porter, American Goldfinch, Ideaform Inc.;

Figure 3 Tom and Cathy Saxton, Hummingbird,;

Figure 4 John Franklin,;

Figure 5 Art Wolfe/Science Photo Library;

Figure 6 Roger W. Barbour/Morehead State University;

Figure 7 Peter Menzel/Science Photo Library;

Figure 8 Leonard Lee Rue/Science Photo Library;

Figure 9 Roger W. Barbour/Morehead State University;

Figures 10, 14 Strumwasser, F. (1960) Some physiological principles governing hibernation. Bulletin of the Museum of Comparative Zoology, 124, Harvard University;

Figures 11, 19 Lyman, C. P. and O’Brien, R. C. (1960) Circulatory changes in the thirteen-lined ground squirrel during the hibernating cycle. Bulletin of the Museum of Comparative Zoology, 124, Harvard University;

Figures 15, 17 Mussacchia, X. J. and Volkert, W. A. (1971) American Journal of Physiology, 221. American Physiological Society;

Figure 21a and b Hayward, J. and Lyman, C. P. (1967) Nonshivering heat production during arousal from hibernation and evidence for the contribution of brown fat, Fisher, K. et al. (eds), Mammalian Hibernation III. 1967 Oliver and Boyd;

Figure 22 Leming Shi, Ph.D., Principal Investigator at the U.S. FDA’s National Center for Toxicological Research (NCTR), Jefferson, Arkansas;

Figure 24 Erik Z. Yu and John M. Hallenbeck (2002) Elevated arylalkylamine-N acetyltranserase (AA-NAT)…, Molecular Brain Research, 102. Elsevier Science;

Figure 25a, b Frerichs, K. U. and Smith, C. B. et al. (1998) Suppression of protein synthesis in brain…, Proceedings of the National Academy of Sciences, 95. National Academy of Sciences;

Figure 26a Malatesta, M. et al. (2002) Quantitative ultrastructural changes of hepatocyte constituents…, Tissue and Cell, 34. Elsevier Science;

Figure 26b Azzam, N. A., Hallenbeck, J. M. and Kachar, B. (2000) Membrane changes during hibernation, Nature, 407. Nature Publishing Group;

Figure 27a and b Ortmann, S. and Heldmaier, G. (2000) Regulation of body temperature and energy requirements…, American Journal of Physiology, 278. Copyright © American Physiological Society;

Figure 28 Dawn Sadler, Open University;

Figure 29 Buck, C. L. and Barnes, B. M. (2000) Effects of ambient temperature on metabolic rate…, American Journal of Physiology – Regulatory Integrative Comparative Physiology, 279. Copyright © American Physiological Society;

Figure 30 Boutilier, R. G. and St-Pierre, J. (2002) Adaptive plasticity of skeletal muscle energetics in hibernating frogs: mitochondrial proton leak during metabolic depression, Journal of Experimental Biology, 205. Copyright © Company of Biologists Ltd;

Figure 31a and b Zimmer, M. B. and Milsom, W. K. (2002) Ventilatory pattern and chemosensitivity…, Respiratory Physiology and Neurobiology, 113. Elsevier Science;

Figure 32 Schleucher, E. (2001) Heterothermia in pigeons and doves reduces energetic costs, Journal of Thermal Biology, 26. Elsevier Science;

Figure 33 Koteja, P. et al. (2001) Energy balance of hibernating mouse-eared bat Myotis myotis… Acta Theriologica, 46. Polska Akademia Nauk, Zaklad Badania Ssakow;

Figure 34 Diana Weedman Molavi, PhD, Washington University School of Medicine;

Figure 37 Heller, H. C. (1977) Pflugers Archiv, 369, Springer Verlag GmbH & Co KFigureG;

Figure 39 Masaaki Hashimoto et al. (2002) Arousal from hibernation and BAT thermogenesis against cold…, Journal of Thermal Biology, 27. Elsevier Science;

Figure 40 Quezzani, S. E. et al. (1999) Neuronal activity in the mediobasal hypothalamus of hibernating jerboas, Neuroscience Letters, 260. Elsevier Science;

Figure 41a Popov, V. I. (1992) Repeated changes of dendritic morphology in the hippocampus of ground squirrels…, Neuroscience, 48. Elsevier Science;

Figure 41b Panula, P. et al. (2002) The histaminergic system in the brain…, Journal of Chemical Neuranatomy, 18. Elsevier Science;

Figure 41c Sallmen, T. et al. (2003) Intrahippocampal histamine delays arousal from hibernation, Brain Research, 966. Elsevier Science;

Figure 42 Pitrosky, B. et al. (2003) Research report – S22153, a melatonin antagonist dissociates…, Behavioural Brain Research, 138. Elsevier Science;

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