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Issue 17: Keeping Warm
At Home in the Cold
by Stephen Whitt
Imagine that you are in the Arctic or Antarctica. What do you see? You might have pictured
either the Arctic Ocean or the Southern Oceans, which surrounds Antarctica. These oceans are
cold, but full of life. Many of the living things in polar oceans actually depend on the cold water
all around.
What kinds of animals live in these cold oceans? Penguins, whales, and walruses, to name a few.
Like you, these animals produce heat all the time. Their bodies turn energy from food into heat.
We say that these types of animals are warm-blooded because they make their own heat. That
heat constantly escapes their bodies.
This heat loss is a problem on land, but it is a real emergency in water. If you were plunged into
the icy cold waters of the polar regions, you would quickly lose all your body heat. Yet many
warm-blooded creatures are able to survive. How?
The answer is insulation. These animals’ bodies have a thick layer of fat called blubber.
Blubber helps hold in the heat even in the coldest of waters.
The system works so well that many of these creatures depend on the water to survive. If a whale
is stranded on land, its blubber may cause it to overheat. Air can’t remove heat fast enough to
keep the creature cool. The whale may die from its own internal heat.
In water, though, whales, walruses, and penguins are right at home. Not too cold, not too warm,
their bodies are perfectly adapted for the chilly waters all around them.
While warm-blooded animals need blubber to live in the polar waters, how could cold-blooded
animals like snakes, turtles, salamanders, and fish survive? These creatures don’t make their own
heat. Instead they depend on the environment to warm them up.
Indeed, it is rare to find any of these kinds of animals in the polar regions. On land, that is. Yet
the waters near the poles are full of many different kinds of cold-blooded fish.
What adaptations allow fish to survive in these cold waters? Some species, such as Arctic cod,
actually have antifreeze proteins in their blood. The antifreeze proteins keep the fish’s blood
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Issue 17: Keeping Warm
from freezing solid, even as its body temperature drops. This fish antifreeze is so good that food
engineers even use it in – are you ready for this? – ice cream!
If ice cream freezes improperly, large ice crystals can ruin its texture. Adding fish antifreeze to
the ice cream can keep it tasting smooth, creamy, and delicious. Yum!
Other fish have even stranger adaptations than the Arctic cod. Consider the strange case of the
crocodile icefish. All fish have blood. For most fish, red blood cells carry oxygen through their
bodies. Their cells need oxygen to survive. In very cold water, oxygen is plentiful. This is
because the colder the water gets, the more oxygen the water can hold.
The crocodile icefish lives the cold waters of the Southern Ocean. This fish has blood, pumped
by an oversized heart. But the blood isn’t red! Instead, the crocodile icefish’s blood is completely
clear. Its blood looks just like water. In fact, the icefish’s blood is seawater, with only a few
white blood cells mixed in. The red blood cells are missing.
Blood really is thicker than water. As blood gets cold, it becomes sluggish. Think of pancake
syrup that’s been kept in the refrigerator. A fish with thick, cold, sluggish blood might have a
hard time surviving in the Southern Ocean. The crocodile icefish doesn’t have this problem
because it doesn’t have any red blood cells.
But how does the icefish live without red blood cells? The cold seawater is so rich in oxygen that
the icefish doesn’t need them. Instead the fish pumps seawater through its body. The icefish gets
all the oxygen it needs right from the cold water. The icefish doesn’t just tolerate cold water. It
actually depends on cold water to stay alive.
Most of us live where the weather is warmer. We enjoy the feel of the sunlight on our skin. We
like the warmth that comes with long summer days. But for animals adapted to colder climates,
their icy world isn’t just home; it’s the only place they can survive.
--------------------------------------------------------------------------------------------------------------------Glossary
adaptations – structures or features of an organism that help it meet a particular need in its
natural habitat
antifreeze – a substance that keeps a liquid from freezing
Flesch-Kincaid RL = 5.0
Copyright December 2009 – Ohio State University. Funded by the National Science Foundation. This work is
licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License.
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Issue 17: Keeping Warm
blubber – a layer of fat that helps ocean animals stay warm
cold-blooded – describes an animal whose body temperature changes as the temperature of its
surroundings changes
insulation – a material that does not conduct heat well
warm-blooded – describes an animal whose body stays the same temperature regardless of the
temperature of its surroundings
Flesch-Kincaid RL = 5.0
Copyright December 2009 – Ohio State University. Funded by the National Science Foundation. This work is
licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License.