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Time: 10 hours
Level: Introductory
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 Introduction Resource- The versatility of mammals is a central theme of the ‘Studying mammals’ series of units, but surely no environment has tested that versatility as much as the rivers and oceans of the world. Mammals are...
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| | 1 The pinnipeds, sirenians and cetaceans
- 1 The pinnipeds, sirenians and cetaceans Resource
- As you work through this unit you will come across boxes, like this one, which give you advice about the study skills that you will be developing as you progress through the unit. To avoid breaking up...
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- 2.1 Land versus water Resource
- Mammals share a number of biological characteristics that mark them out as members of the class Mammalia. Many of these are adaptations to a life on land. For example:
- 2.2 Breathing air Resource
- A swimming elephant can breathe by holding the end of its trunk out of the water, but if it tried to find its food under the surface, like the desman, it would have to hold its breath. Neither the mammalian...
- 2.3 Moving about Resource
- Water is more viscous than air, so it can take more effort to move through water (try running in a swimming pool). Friction between the body and the water causes turbulence, which holds a swimmer back,...
- 2.4 Staying warm … Resource
- In this section, you will meet the term ‘thermal conductivity’ and you will be asked to accept that it is ‘a measure of how readily heat flows from a particular material’. You may be uncomfortable about...
- 2.5 … and getting larger Resource
- Size offers a number of biological advantages, including some protection from predation, but it can also help in reducing heat loss. A large mammal has a large body mass (generating heat) relative to its...
- 2.6 Senses and communication … Resource
- Glance down at the second paragraph of this section, where you will find a sentence about the speed at which eyes adapt from bright light to poor light, and the statement that this process takes 20 minutes...
- 2.7 … and becoming more intelligent Resource
- Intelligence is a useful commodity: it can help an animal to make sense of its environment and cope with the demands of social behaviour (including courtship and competition). Hunters tend to be relatively...
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- 3.1 Features of the diving response Resource
- All the aquatic mammals' adaptations to life in the water – breathing, moving, staying warm and making sense of the environment – come together in their diving behaviour, and the diving abilities of marine...
- 3.2 Natural dives Resource
- The physiology of the diving response can be studied in the laboratory, but investigating the behaviour of a diving mammal in its natural environment can be more of a problem. However, modern physiological...
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| | 4 The evolution of whales
- 4.1 The rate of evolution Resource
- I now want to move away from looking at the challenges facing all aquatic mammals, to examine very briefly what we know about the evolutionary history of the cetaceans. This group has travelled furthest...
- 4.2 Intermediate forms Resource
- In essence, the argument about intermediate forms runs as follows. If whales evolved from a terrestrial ancestor through the accumulation of small differences over time, we should expect to find the fossils...
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| | References and Acknowledgements | |
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