- Info
BIO120 Animals at the Extremes Unit 3: Polar Biology - OPEN University
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Open University
S324_3 14 Hours
Intermediate
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Course Description
This unit is the third in a series of three on Animals at the extreme. In order to get the most from it you should have previously studied
Animals at the extreme: the desert environment (S324_1)
and
Animals at the extreme: hibernation and torpor
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By the end of this unit you should be able to:
- define and use, or recognize definitions and applications of each of the bold terms;
- outline the special features of the polar regions as a habitat and list some contrasts between the Arctic and the Antarctic;
- describe some effects of daylength on feeding, fat deposition and reproduction in arctic animals;
- explain
why the environmental controls of appetite, activity level and
fecundity are essential adaptations to living at high latitudes and
describe some physiological mechanisms involved;
- describe some adaptations of fuel metabolism and bone formation to dormancy in bears;
- describe the metabolic control of prolonged fasting in breeding polar bears and penguins;
- explain
the use of comparative studies to identify anatomical and physiological
adaptations to thermal insulation in aquatic and terrestrial endotherms;
- describe some adaptations of the blood, respiratory system and muscles of fish to the polar environment;
- explain the role of fatty acid profiles in investigating the diet of polar vertebrates.
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Introduction
 Introduction Resource- This unit is the third in a
series of three on Animals at the extreme. In order to get the most
from it you should have previously studied Animals at the extreme: the
desert environment (S324_1) ...
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1 Polar biology
- Preamble Resource
- This unit is about animals'
structural and physiological adaptations to living permanently in cold
climates; hibernation, a special response to transient or seasonal
cold, is described in the openlearn...
- 1.1 The polar environment Resource
- At high latitudes, the Sun's rays
always strike the Earth at a large angle from the vertical so they
travel through a thicker layer of atmosphere and are attenuated by the
time they reach the ground. Because...
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2 Environmental regulation of physiological processes
- 2.1 Nutrient budgeting Resource
- All plants and animals respond to
environmental changes such as the light–dark cycle and temperature, but
the impact of the environment on essential physiological processes such
as eating, fattening and...
- 2.2 Migration for breeding Resource
- Birds do not hibernate, but like
reindeer, many species undergo daily or seasonal changes in energy
expenditure and appetite, and many of the endocrine changes that are an
integral part of true hibernation...
- 2.3 Environmental regulation of breeding Resource
- As pointed out in Section 1.1,
primary plant productivity occurs for only a few months in the summer,
so the reproductive physiology of most arctic animals, particularly
herbivorous species, is tightly...
- 2.4 Variable fecundity Resource
- The food supply for most polar
species depends on several unpredictable factors so successful breeding
is far from certain, even if births are tightly synchronized with the
seasons. Maintaining pregnancy...
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3 Natural feasting and fasting
- Introduction Resource
- It is clear from Sections 1 and 2
that seasonal or irregular periods of fasting are an integral part of
living at high latitudes, especially for large animals. When people
(and many tropical and temperate-zone...
- 3.1 Penguins Resource
- Penguins (order Sphenisciformes)
are an ancient and distinctive group of flightless, short-legged birds
that evolved in the Southern Hemisphere, probably around New Zealand,
about 65 Ma ago in the late...
- 3.2 Bears Resource
- Brown or grizzly bears (Ursus
arctos), and black bears (U. americanus) feed throughout the summer on
grass, fruit, nuts, fish, small mammalian prey and carrion. In autumn,
all brown and black bears fatten...
- 3.2 Bears (continued) Resource
- Polar bears (U. maritimus) are
almost entirely carnivorous and are the only living species of bear to
obtain almost all their food from the sea. Their main prey is ringed
seals (Phoca hispida), both adults...
- 3.3 The structure of adipose tissue Resource
- Since food is only available
seasonally or intermittently at high latitudes, many arctic birds and
mammals, including polar bears, Svalbard reindeer, arctic foxes, seals
and walruses, naturally accumulate...
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4 Thermal insulation
- 4.1 Insulation in terrestrial endotherms Resource
- For organisms of similar size and
shape in a similar thermal gradient, the rate of heat loss from
convection is up to 90 times as fast in water as in air, so in
temperate climates, aquatic endotherms need...
- 4.2 Insulation in aquatic endotherms Resource
- Most seals and sealions (order
Pinnipedia) are furred. The adult fur usually consists of short, dense
stiff guard hairs that are oily from profuse secretions of the
sebaceous glands. The hair probably...
- 4.3 Humans in polar regions Resource
- Humans evolved in tropical Africa
and gradually colonized colder climates during the Pleistocene ice
ages. There have been permanent populations in the Arctic for several
thousand years, mostly Inuit (Eskimos)...
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5 Polar ectotherms
- Introduction Resource
- The land and shallow water
experience at least a brief summer at high latitudes, so terrestrial
and freshwater ectotherms can be active during warm periods and
hibernate when the temperature is below freezing....
- 5.1 Passive properties Resource
- Freezing is nearly always harmful
to living cells because the tertiary structure of hydrophilic molecules
such as proteins is disrupted and the permeability of membranes is
drastically altered. The concentration...
- 5.2 Metabolism Resource
- Molecules diffuse more slowly at
low temperature: measurements of the rates of diffusion of small
molecules such as lactic acid, Ca2+ and analogues of glucose and ATP
through fish muscles produced Q10...
- 5.3 Fatty acids as indicators of diet Resource
- Although polar fish and
invertebrates are difficult to study alive for the reasons just
described, some information about their diet and habits can be obtained
from analysis of the lipid composition of...
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6 Conclusion
- 6 Conclusion Resource
- There is much more to living in
polar regions than insulation against the cold. Food may be very
scattered both in space and in time and breeding must be tightly
synchronized to seasons and food availability....
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Unit questions
- Unit questions Resource
- Which of the factors (a)-(g)
is/are a valid reason(s) for the fact that penguins are numerous and
diverse around Antarctica but absent from the Arctic?
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References and Acknowledgements
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Copyright 2007,
by the Contributing Authors.
Cite/attribute Resource.
administrator. (2010, January 03). BIO120 Animals at the Extremes Unit 3: Polar Biology - OPEN University. Retrieved September 04, 2010, from Free University Courses OCW Courses OpenCourseWare Freeversity Foundation Web site: http://www.freeversity.org/science-and-mathematics/biology/bio120-animals-at-the-extremes-unit-3-polar-biology-open-university.
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