Sondra Weigand, age 11, of Delmar, N.Y., for her question:
What is the turtle family?
The slowpoke turtle can take his time because his armor plating protects him from most of his hungry foes. His relatives have dawdled through some 200 million years, making hardly any changes in their way of life. Of all the backboned animals, their family tree is the oldest, older even than the long gone dinosaurs.
In everyday language, we might expect the family to include all the 200 or so different turtle species. But scientists classify this sizable group of armor plated reptiles as an order. To them, the ancient and durable turtles and land dwelling tortoises belong in the Order Chelonia. The fancy name is coined from the Greek word for the tortoise.
As usual, the large order is subdivided into smaller family groups. Each family has several genera or genus groups; and each individual species belongs in its own genus. All of these 200 or so coldblooded creatures belong in the great Class Reptila, along with the assorted snakes, lizards and crocodiles.
Experts separate the turtle group into a dozen or so different families. One family belongs to about 40 large and small land dwelling tortoises, at home on all continents and many islands. Eleven or so families belong to various large and small turtles, who enjoy their lazy lifestyles in the fresh and salt waters of the world. Since all the chelonians are coldblooded creatures, they avoid the polar land areas, but they are at home almost everywhere else.
The whopping leatherback is a seagoing turtle which has a leathery shell with hard ridges. He may weigh three quarters of a ton, and from side to side, from flipper tip to flipper tip, he may measure 12 feet. This remarkable chelonian is the one and only member of the Family Dermochelyidae. Five or six other huge seagoing turtles are classified in the Family Cheloniidae. Their limbs are flippers and they have hard shells.
Another family of soft shelled turtles are smallish fellows, at home in freshwater lakes and streams. Three of these species are native North Americans. Their pliable leathery shells enable them to be somewhat more frisky than the typical armor plated turtles.
Several turtles have clever devices for protecting their heads. Those that bend the head and neck to the side belong in one family, those that use an S shaped curve belong in another. Many of them share their freshwater habitats with a family of about 20 species of mud turtles and musk turtles.
The members of each family are classified in small genus groups. The Family Chelydridae has but two genera, each with only one species. One member of this small family is the bad tempered snapping turtle, the other is the equally bad tempered alligator snapping turtle and both species are native North Americans.