Cheri Shockley, age 12, of Spokane, Wash., for her question:
What are cold‑blooded animals?
The term cold‑blooded animal brings to mind the clammy toad and the slippery eel, the scaly fish and slithery snake, Most of us tend to think that these humble creatures are far out‑numbered by the so‑called warm‑blooded animals. But this is far from true, Remember that the oysters and the insects, the sponges and all the single‑celled animals are also cold‑blooded creatures. In fact, most of nature's children are cold‑blooded and always have been. The only warm‑blooded animals are birds and mammals and, in the long story of life on earth, they arrived only recently.
Every animal needs warmth to keep his body processes going and remain active. However, at the boiling point of water, the protoplasm which fills every living cell is destroyed, so an animal cannot use too much warmth. The first animals got their needed warmth from the water and much later, some of them took their warmth from the air and the ground. Most of the animals in the world today still depend for their necessary body heat upon their surroundings.
The method has advantages and drawbacks. A fish can survive being frozen solid. But a lizard cannot sweat to cool himself from the desert sun. As a rule, these animals are about one degree cooler than their surroundings. The natural temperature which your body tries to maintain is about 98 degrees ‑ and the air seldom gets this hot. Frogs and toads, snails and salamanders seem cool to the touch ‑ which is why we call them cold‑blooded creatures. But a lizard basking in the desert sun may have a body temperature of 100 degrees or more.
As a rule, the so‑called cold‑blooded creatures, then, are merely a little cooler than our bodies, But if we got as hot as they sometimes do, we would be down with raging fevers. For this reason, it is more correct to call them creatures of varying body temperatures. If you wish to beimpressive, you may call them the poikilothermal ‑ in which case you would be homoiothermal.
When meeting big words of this sort, Andy always grabs them boldly by the tail and tackles the last section first. In both poikilothermal and homoiothermal, the last section means temperature, as it does in thermostat, The poikilo part means varied and a poikilothermal animal can vary his temperature from very cold to very warm. the hambio section means alike or similar, A homoiothermal animal has a more or less even body temperature.
Changing temperature speeds up the activity and the body processes of a poikilothermal creature, In cold water, the fishes need much more food to stay active, The snake is busiest in warm, tropical weather and gets loggy and lazy in the cold. Bees perish when the temperature in the hive falls below freezing, but the pesky boll weavil can survive 14 degrees below freezing, Certain fish can be frozen solid, when even the heart stops. But if the temperature is raised gently, they can revive to swim another day.