Susan Israe1, Age 9, Of Winnipeg, Manitoba, Canada, for her question:

When did the first animals come on land?

The first living things were very small, perhaps too small for our eyes to see.  Only an expert could tell which of them were animals and which were plants. Later, much later there were animals like small worms and gobs of jelly  and much, much later there were creatures that lived in curly shells. All these early animals lived in the sea.

The experts are quite sure that the story of living things began in the seas. The first simp1e animals grew bigger and improved themselves. But for ages none of them could take their oxygen from the air. The fishes and other sea dwellers had gills for taking their oxygen from the water. For this reason none of the first animals could leave the ancient seas to cope with life on the dry land.

The continents were bare and barren. There were mountains and valleys, steep cliffs and spreading plains. But there was no grass and no gentle deer to graze there. There were n0 foxes to hunt the bunnies, for there were no bunnies. There were no birds in the air, no frogs and no snakes. Then, perhaps 350 million years ago, certain fishy animals of the sea began to change their breathing habits. They were somewhat like the lung fish that now live in africa  for they had simple lungs for taking oxygen from the air as well as gills for taking oxygen from the water.

These fellows may or may not have been the first animals to leave the seas for life on the land. We are not surf. But we do know that certain lobster type animals learned to breathe air, and these daring creatures deserted the sea more than 300 million years ago. They were the ancestors of the scorpions that still make their homes on the

The scorpions may we11 have been the very first animals to set up permanent housekeeping on the continents. But the land already was covered with patches of plants, for many a1gae and seaweeds left the seas long before the first animals came to join them. The scorpions may have had the continents to themselves for perhaps 100 million years. Then they were joined by a variety of winged insects. A few million years later they were joined by the waddling amphibians who were the ancestors of our frogs and toads.

The most advanced animals are the ones that have backbones. Scorpions and insects have no bones at all, and the first backboned animal to conquer the dry land was a sizable salamander. He was an amphibian who lived through an egg and a fishy tadpole stage in the water. Later in life he swapped his fishy gills for a pair of lungs and spent much of his time breathing air on the dry land. The salamanders and frogs who descended from this brave pioneer still spend their kindergarten days in the water and their later lives on the land.