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Generally in nature, an animal must seek shelter from bad weather or from a threatening situation. Imagine a creature carrying its shelter or its house with it wherever it goes. When threatened, it simply retreats into its house and locks the door. That’s essentially how turtles live their lives. The turtle’s shell is a remarkable feat of natural engineering, a protective gift from God. The shell has two parts?the carapace, the upper section and the flat belly section called plastron. They are connected by bony bridges leaving gaps for the head, tail and four legs. The turtle’s vertebrae and ribs have actually become an integral part of the carapace and do not move separate from the shell. When the turtle withdraws into this shell, it’s almost impossible for a predator to get at it. The shell accounts for about one third of the weight of a turtle, yet most turtles are agile, strong walkers or swimmers and many climb with great ease. They have developed strong legs, especially in giant species, like the Galapagos tortoise which travels great distances, although slowly. They could carry the weight of a man on their back and keep right on going. The tortoise travels about 4 miles a day. On the other hand, sea turtles have developed flipperlike legs and sleek shells. They swim at about 20 miles an hour. The distance a sea turtle might travel in one hour would take a week for a tortoise to cover. Turtles are ancient life forms. The earliest fossils recognized
as turtles date from the Triassic period, about 200 million years
ago. Turtles were in existence prior to the emergence of the great
dinosaur groups and survived the demise of the dinosaurs, continuing
to adapt and flourish. Turtles occupy almost every imaginable habitat—woods,
ponds, rivers, lakes, marsh-lands, prairies, deserts and the open
ocean, and they eat food as varied as insects, tender seagrasses,
carrion, fruit and fish. |
Turtles have great similarity yet great variation as well. The Galapagos tortoise evolved on islands with no predators and little competition. They grow very large—500-600 pounds—and live 100-150 years. Desert tortoises are much smaller. They eat cactus fruit and desert grasses and because of their environment, God has given them adaptations to be able to survive without water. They get the moisture they need from the food they eat. The pancake tortoise of Africa has a flat, soft shell, instead of the hard dome common to most turtles. It looks sort of like someone dropped a frying pan on him. This allows him to easily climb rocks and lie under them. When threatened, he will wedge himself into a rocky crevice and then inflate his body so he’s almost impossible to pull out. The red toad-headed turtle with its brilliant red head is an example of the variation in bright and beautiful colors. Various beautiful design patterns on the shell show God’s wondrous creation. These include map turtles, so named because of the intricate patterns of yellow lines that actually look like lines on a topo map; the radiated tortoise of Madagascar has yellow circles with lines radiated out from them; and the leopard tortoise of Africa whose shell is covered with distinctive and beautiful yellow spots. One fascinating turtle species is the alligator snapping turtle, which may grow to 200 pounds. He lives on muddy river bottoms, sitting quietly with his brown shell blending with the mud. He keeps his mouth open and wiggles his tongue which is a bright pink. Like a lure, this attracts fish which swim right in and the turtle simply snaps its mouth shut. They may move no more than a few feet their whole lives. Tortoises live almost exclusively on land. Many turtles move between land and water. Sea turtles spend virtually |
their whole life in water. The female comes out to lay eggs and she will return to the very beach where she was hatched. The whole process is truly amazing. She comes on shore, usually at night, and digs a nest into which she lays up to 100 eggs. She buries the eggs and leaves. As the embryo grows into a fully developed hatchling, the shell that has offered nourishment and protection becomes a kind of prison from which the baby turtle must escape. God has provided an “egg tooth,” actually a horny projection located on the tip of the snout (which disappears as the turtle grows). The tiny hatchling uses it to pierce its shell, then pulls it apart with his forelimbs. All eggs in a nest hatch at virtually the same time and they use that community spirit in order to escape from the nest. Experiments with single eggs show that few break free on their own. Together the baby turtles scrape down the walls and ceiling of the nest and instinctively climb upward till they break free. Then these hatchlings, only a couple of inches long, know that they must scramble for safety, perhaps a hundred yards or more across the open beach to the sea. And it’s not just the hundred-yard dash that’s difficult; predators of all kinds are waiting—birds, dogs, skunks and others seem adept at knowing where nests are and when they will hatch. Only a fraction make it to the sea and even then they are easy pickings for large fish and sea gulls. Little is known of the first year of wild hatchlings. They simply disappear from sight, going weeks without food if necessary and struggling to escape predators of all kinds. Those that survive to adulthood will spend their lives, perhaps 50 years, swimming around in the open ocean. The male turtles may never leave the ocean their whole life; the female only to lay eggs. We do not understand how turtles, migrating over great Cont’d on page 4 |
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