we have some cold deserts, where year round cold and unmelting
snow create environments where life forms face formidable challenges.
This environment is found on
the peaks of high mountains and near the poles. Parts of the
Antarctic are cold deserts, and the inland mountains of Greenland
are deeply buried in snowfields.
When the weather is so cold that snow never melts, the annual
rainfall (snowfall) is not an important factor for life forms.
Although scientists have found some bacteria living underneath
glaciers, life forms in this environment are generally just visitors.
Parts of these icy environments
are in motion. Glaciers slowly flow downhill or toward the oceans,
carving out the landscape as they go. As glaciers move, sometimes
the ice cracks and deep crevasses are formed. If you stand near
a glacier you can hear creaking and cracking sounds as the ice
Cold air does not hold much water
vapor. The driest deserts on earth are the dry, cold deserts
in Antarctica. Some places in Antarctica haven't received any
rain for 4 million years, although they do receive water from
the runoff from nearby mountains when some of the snow melts.
There are even lakes in these deserts,with thick layers of ice
on them. These cold deserts are even more difficult to live in
than hot deserts are.
There are some native life forms
even in Antarctica. There are algae in the lakes in the
dry interior valleys, and bacteria, and some tiny nematode worms.
When the cold is at its worst, some of these organisms go into
a sort of cryo-death, living in a frozen state of suspended animation.
Near the coast there are even two species of flowering plants,
one of which is a grass.
Where the snows are perpetual in cold
deserts, there is nothing to eat. The ground may be far down
under the snow, and may be frozen in any case. Sometimes the
snow may have a patches of pinkish areas in the summer:
these are algae which are growing in water that the sun has melted
during the day. A few nutrients may have been blown onto the
snow as fine dust. However, the cold returns during the night.
Insects may get blown onto the snow fields, birds may fly over
them, but these areas are essentially lifeless. For much of the
year all the water is frozen, and so, for living creatures, thirst
is also a problem.
despite the challenging conditions near the poles, life forms
that are dependent on the ocean live on its shores. The cold
ocean waters swarm with life. Penguins eat krill, octopus and
fish: they congregate on the cold shores of the Antarctic
to raise their chicks. This environment provides a relatively
safe place for flightless birds to gather, though there are still
still some predators. There is food in the ocean. Some of the
fish in these cold waters even have anti-freeze-like molecules
in their cells, which protect them from being frozen solid.
The arctic ocean also has a
sea-based ecology. Again, migrating birds swarm to some parts
of the tundra to raise their young. Seals live on fish in the
arctic ocean, and polar bears prey on the seals. Walruses dig
for clams on the sea bottom with their long tusks.
Go on to
a Cold Desert Food Web
Introduction to Desert Biomes
Return to Introduction
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