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BIO113 Studying Mammals Unit 7: Return to the Water - OPEN University
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Open University
S182_7 10 Hours
Introductory
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Course Description
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 essentially a terrestrial group of animals, but three major
groups have independently adopted an aquatic way of life. In moving to
the water, aquatic mammals have had to survive, feed and reproduce using
a set of biological characteristics that evolved in association with
life on land. This unit will explore how these characteristics have
provided challenges, and opportunities, for mammals that spend some or
all of their time in the water.
This is the seventh in a series of units
about studying mammals. To get the most from these units, you will need
access to a copy of The Life of Mammals (2002) by David
Attenborough, BBC Books (ISBN 0563534230), and The Life of Mammals (2002) on DVD, which
contains the associated series of ten BBC TV programmes. OpenLearn unit S182_8 Studying mammals: life in the trees
contains samples from the DVD set. You should begin each unit by
watching the relevant TV programme on the DVD and reading the
corresponding chapter in The Life of Mammals. You will be asked
to rewatch specific sequences from the programme as you work through the
unit.
By the end of this unit you
should be able to:
- contrast the physical
properties of air and water and describe implications of such
differences for aquatic mammals;
- give
examples of the adaptations displayed by aquatic mammals that enable
them to hold their breath while submerged for relatively long periods;
- describe some of the biological differences between
pinnipeds, sirenians and cetaceans;
- discuss
the importance of communication by sound in aquatic mammals, describe
the role of blubber and explain countercurrent heat exchange;
- explain the diving response and its significance in
natural dives;
- explain how the
evolution of whales can be described within the conceptual frameworks of
natural selection and punctuated equilibria.
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Introduction
 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 Living in the water
- 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 The ‘diving response’
- 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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There are currently no items in this folder.
Copyright 2007,
by the Contributing Authors.
Cite/attribute Resource.
administrator. (2010, January 30). BIO113 Studying Mammals Unit 7: Return to the Water - OPEN University. Retrieved March 10, 2010, from Free University Courses OCW Courses OpenCourseWare Freeversity Foundation Web site: http://freeversity.org/science-and-mathematics/biology/bio113-studying-mammals-unit-7-return-to-the-water-open-university.
This work is licensed under a
Creative Commons License
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