Classification System for Turtles.

Most authorities separate straight-necked turtles into seven distinct families: Chelydri-dae, snapping turtles; Kinosternidae, mud and musk turtles.

Trionychidae, soft-shell turtles; Emydidae, semiaquatic turtles; Tes-tudinidae, tortoises; Chelonidae, sea turtles; and Dermochelyidae, leatherback turtles.

Several of these families have certain char-acteristics in common, they will be treated as five groups: snapping, mud and musk turtles; soft-shell turtles; semi-aquatic turtles; tortoises; and marine turtles (sea turtles and leatherback turtles).

A few turtles belong to the suborder Pleurodira, or side-necked turtles, which means that they lay their necks and heads sideways in the groove between the carapace and plastron (upper and lower parts of the shell).

The alligator snapper (Macroclemys temmincki) lies motionless on the bottom of streams, ponds, and lakes with its mouth open. Its tongue appears to be a red, wriggling worm, and unsuspecting fish looking for a meal become the snapper's prey.