At Home in tHe Coldby Stephen Whitt

deCember 2009

At Home in tHe Cold At Home in tHe Cold

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Copyright December 2009 - The Ohio State University

Supported by the National Science Foundation

about the authors

http://beyondpenguins.nsdl.org

issue 17: Keeping Warm (december 2009)

Find this story and others at:

http://beyondpenguins.nsdl.org/information.php?topic=stories

Stephen Whitt

Director of Experience Programs Teaching and Learning COSI

Stephen Whitt has been with COSI since 1993, performing shows and demonstrations, writing exhibit signs and show scripts, and co-directing COSI’s f loor faculty. He has written over 40 articles for children’s science magazines, and his first book, called The Turtle and the Universe was published by Prometheus Books in 2008.

Licensed under a Creative Commons license.http://creativecommons.org/licenses/by-sa/3.0/

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 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!

Artic cod have antifreeze proteins that keeps their blood from freezing solid. Photo courtesy of http://www.arcodiv.org

At Home in tHe ColdAt Home in tHe Cold At Home in tHe Cold

At Home in tHe Cold

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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

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.

Warm blooded animals turn energy from food into heat.

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.

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.

At Home in tHe ColdAt Home in tHe Cold

At Home in tHe ColdAt Home in tHe Cold

Imagine that you are in the Arctic or Antarctica. What do you see? You might have pictured either the Arctic Ocean or the Southern Ocean, 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.

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.

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a particular need in its natural habitatAntifreeze – a substance that keeps a liquid from freezingblubber – a layer of fat that helps ocean animals stay warmCold-blooded – describes an animal whose body temperature changes as the temperature of its surroundings changesinSulAtion – a material that does not conduct heat wellWArm-blooded – describes an animal whose body stays the same temperature regardless of the temperature of its surroundings

Walruses are perfectly adapted for the chilly waters all around them. Photo courtesy of Heather Thorkelson via Flickr.

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.

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

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At Home in tHe ColdAt Home in tHe Cold

At Home in tHe ColdAt Home in tHe Cold

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.

A layer of blubber helps hold in heat even in cold water. Photo courtesy of Andrew Davies via Flickr.

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

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.

The icefish does not have blood. Instead, it pumps ocean water through its veins. Photo courtesy of Wikipedia.