Jeff Katz, age 11, of Milwaukee, Wis., for his question:

WHAT WERE THE FIRST LAND ANIMALS LIKE?

The first animals got their start in the ancient seas. For maybe a billion years or so, they improved themselves and branched out in various shapes and sizes. At last a few bold ones ventured out onto the dry land. It would be nice to think that these first land dwellers were pleasant, peaceable characters. But all the evidence indicates that they were no6t.

The positive proof depends on fossil remains preserved in ancient rocks. If the first dwellers were small, soft bodied animals, they were too fragile to leave such durable fossils behind. For this reason, the story of the first land animals is uncertain.

Perhaps they were related to the lobe finned fishes. They had gills and air breathing lungs, and their fins were attached to simple, lobe like limbs. These odd fishes could survive even when stranded in dried up ponds and streams. They left fossils which prove that some of them left the sea to live on land about 364 million years ago.

Meantime certain wormy sea dwellers were making drastic changes. Eventually they left the sea to become the ancestors of the insect world. No doubt the first land dwelling insects were too fragile to leave durable fossils. But we have plenty of proof that many highly developed insects populated the coal forests more than 300 million years ago.

However, we have fossils of still another land dweller, dating back about 400 million years. He belonged to the vast phylum of arthropods, the animals with tough, jointed shells or skins. His relatives included the lobsters and shrimps who remained in the sea.

This bold adventurer onto the dry land was the ancestor of 650 different scorpions that inhabit warm regions of our modern world. His segmented body had four pairs of walking legs, one pair of nasty pincers and a downright deadly sting in his long, curled up tail.

Maybe the bad tempered scorpion was the first land¬dwelling animal. At any rate, his fossil record proves that he left the sea some 400 million years ago. However, someday we may find fossils to prove that lobe finned fishes or ancestral insects conquered the land even earlier.