TURTLES 
(Tortoises, Terrapins and Turtles) 
The term “turtle,” has been broadly applied to the four-limbed animal 
dressed by nature in an armor sometimes as invulnerable as the metal suit 
of warrior knights. To most people a turtle is a turtle whether it swims in 
the sea, lurches cross-country like a miniature army tank, or wallows in 
the mud. It may be a mild, inoffensive vegetarian, or it may hunt and fish 
for its food and snap your finger off if you give it half a chance — and still 
he a “turtle.” 
Scientists, however, speak of the whole family as chelonians, and some 
like Hornaday and Surface further divide them into turtles, tortoises and 
terrapins. Tortoises have dome-shaped top shells and clublike legs and 
spend all their time on land. Turtles dwell in the water and have flippers 
instead of legs. And the terrapins, whose feet are webbed between the toes, 
have the amphibian characteristic of dividing their time between land 
and water. 
Nevertheless, in conformity with custom, we shall call all these crea¬ 
tures “turtles” except in those few cases where usage dictates otherwise. 
Like most other reptiles, turtles are equally distributed over most of the 
temperate and tropical continental regions. Sea turtles inhabit the warmest 
waters of most of the seas and oceans, as they have done throughout much 
of geological history. 
Their shells, the upper called the carapace and the lower called the 
plastron, fit around them like a barrel with the ends knocked out for the 
head, tail and legs. These shell parts are formed by flat, bony ribs, fused 
together and completely covered with a horny exterior. The upper and lower 
shells are connected at the sides by means of bony “bridges.” The protrud¬ 
ing head, neck and limbs are protected by scales or just skin. 
Most backboned animals draw breath by means of movable ribs and 
muscular diaphragms; their chest cavity acts as a bellows to pump air in and 
out. The turtle, however, has ribs fused to the underside of the carapace. 
It is able to force some air into and out of the lungs by raising and lowering 
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