Sometimes it is hard for us to imagine that creatures which are so unlike us have organs very much like ours that function in the same way. Many people think that because a fish lives in the water and is cold-blooded it must lack various organs, or not have certain senses.

Actually, the anatomy of a fish is very much like that of higher warm-blooded animals. In fact, many scientists believe this similarity is evidence that life on land evolved from life in the sea!

Fishes breathe and digest food. They have a nervous system and suffer pain and physical discomfort. They have a very keen sense of touch. They taste as well as feel with their skin. They have two small organs of smell located in the nostrils on the head. They even have ears, but these are internal. Fish have no external ears. Their eyes are similar to those of other vertebrates, but less complicated in structure.

So you see a fish has “systems” to carry on various processes just as we have. Let’s consider briefly just two of these systems-the digestive and the circulatory. A ‘fish’s food passes from the gullet into the stomach which contains gastric glands and where digestion begins. Food goes on into the intestine where it is assimilated, that is, passed on to be absorbed by the blood. Different types of fishes have different digestive systems which take care of their special type of food, ranging from vegetable matter to other fish.

But a fish uses food just as we do, as fuel for the power of life, growth, and motion. The blood stream of a fish carries its food, as well as oxygen, to every organ of the body. The pump which controls the flow of blood in a fish, is the heart, just as in humans. A fish’s heart is located just behind and below the gills. The heart of a fish has three or four chambers, and it contracts rhythmically, just like ours.

There are thousands of different kinds of fishes, each adapted to a special way of life, but with organs, senses, and systems like our own.