Karen Kammerman, age 11, of Washiagton, Ill..for her question:

If you have a pet goldfish, you can study his sleeping habits for yourself. At dusk, most of the birds fly home to roost in a sheltering tree. Does Goldie find himself a bed of water weeds, close his fishy eyes and fall asleep? Not at all. He is as busy after dark as he is in the daytime. Around and around he swims, opening and closing his mouth long after sunset. Perhaps you could catch him napping if you crept down stairs in the middle of the night, No,  he is still swimming around, opening and closing his mouth and staring with his fishy eyes wide open.

The fact is, Goldy never sleeps, day or night. The same holds true for guppies and all the other pet fish. The same holds true for the fish in the rivers, lakes and seas. In the ocean, night is the busiest time for many of the fishes. For then the tuna, the shark and other hungry monsters are on the prowl and the schools of herring and mackerel swim for their lives.

The fishes, all of them, are restless creatures who never sleep or even close their eyes. Now and again they rest a little by swimming slowly or staying in one place, suspended in the water. Such a rest can hardly be called a nap, for the fins are most likely moving, the eyes are open and the swallowing never stops.

You might think that a fish would be worn out with such restless activity. But this is not so. His nervous system is much more simple than that of the higher animals. The cat‑napping Miss Puss, for example, has a far more complex nervous system. She responds to far more things going on around her and during her waking hours her pussycat brain bursts with pussycat ideas. All these impulses in the brain and nervous system make it necessary for her to sleep.

While she naps, she rests her brain and nervous system, just as we do.

The fish has no brain to speak of and he is not aware of much in the watery world around him. If there is food nearby, he tastes it with each mouthful of water, much as we smell food with the air we breathe. If he happens to be hungry, he snaps at it. He is dimly aware of his large enemies and responds by swimming faster. A noise will startle him. These few things do not call for a complicated brain and nervous system which tend to become tired and overburdened at the end of each busy day.

Actually, a fish is not nearly so busy as he seems to be. The opening and closing of his mouth is part of his breathing operation. He takes in a mouthful of water and sends it back through his gills, those round flaps where you would expect his ears to be: Inside there are feathery fringes of tissue which extract oxygen from the water. All that swallowing takes no more effort than the rising and falling of your breathing lungs.

There is a reason, too, why Mr. Fish never closes his eyes. His eyelids are transparent windows, sealed in place. He has no moving eyelids and cannot even blink, let alone close his eyes as we do.