Abby Jarin, age 10, Philadelphia, Penna., for the question:
How do mammals, reptiles and amphibians differ?
The mammals are classed as the highest group of animals. They are warn‑blooded, air‑breathing creatures. They wear coats of hair or fur, or they have the bristly remains of a hairy coat. But the greatest difference between them and all other animals is the way in which they are born. Mammal babies are born alive and fed on mother's milk.
The list of mammals includes most of the familiar animals around us. Cats and dogs are; mammals; so are mica and rats, cows and horses, sheep pigs and deer. Sea‑going seals are mammals; so are walruses and porpoises. The whale is a sea‑going mammal who has lost all but a few bristles of his hairy coat. All these mammal animals are warm‑blooded, breathe air, gives birth to live babies and feed them on mother's milk.
It is not hard to pick out the animals who are mammals, But it is not always easy to separate the reptiles from the amphibians. Both these groups of animals are cold‑blooded and the babies almost always hatch from eggs. But in appearance a salamander may be mistaken for a little lizard. The lizard is a reptile; the salamander is an amphibians This is where the word amphibian is helpful. It means land‑and‑water. The true amphibian spends part of his life in the water and part on the dry land. The true reptile is almost always a creature of the dry land. You can tell the little lizard from the salamander by touching their skins. Reptiles have dry, scaly skins, amphibians have cool, soft, moist skins.
The amphibian begins life as a jelly‑coated egg, either in the water or in some very damp place on land, He hatches into a tadpole and goes through a fishy stage. He has gills and breathes his oxygen from the water as a fish does. Most amphibians grow out of this fishy stage, trade their gills for lungs and become air‑breathing, land‑dwelling adults.
Throughout life, however, the true amphibian likes cool, damp, shady place.
Salamanders and newts are amphibians. These fellows have long, tapering tails like the lizard. Frogs and toads are tailless amphibians. The hellbenders :end mud puppies are amphibians that choose to spend even their adult lives in the water.
As a rules reptiles do not like the water. Most of them like warm, dry places. Most of them hatch from eggs but they do not go through , fishy stage. Crocodiles, snakes, lizards and turtles axe reptiles. The word reptile means a crawling animal. None; of thorn have strong running legs. They crawl or waddle along on short stubby legs and the snake crawls along with no legs at all. Crocodiles, certain turtles and a number of snakes spend their adult lives in the; water. But, being reptiles, they must be born on land. Even the big ocean‑going turtle comes ashore to lay her eggs. A few land snakes give birth to live babies, But no reptile and no amphibian is fed on mother's milk.