TURTLES AND TORTOISES
- Turtles and tortoises are the oldest living group of reptiles. They have looked much as they do today for over 250 million years! That is they already had that iconic shell which no other reptile possesses. One of the only differences betweens the ancient relatives and modern turtles is that prehistoric ancestors had teeth!• Today there are over 300 different species of turtles and tortoises. They live in mostly warmer parts of the world, populating every continent except Antarctica and occurring in every ocean except the Arctic. More than two-thirds of all turtle species live in freshwater.
• The largest turtle that ever lived was the Archelon. It was a prehistoric sea turtle swimming the oceans at the same time the dinosaurs were walking the earth. Scientists estimate that the Archelon weighed close to 5000lbs!!!
• Some of species are still fairly gigantic like the Galapagos and Aldabra land tortoises that can weigh 600 lbs and live over 150 yrs, but the biggest turtle alive today is the leatherback sea turtle coming in at 7ft long and 1500 lbs!!!
• Turtles don't only come in large sizes; in fact the smallest are the musk turtles, which only grow to 5 inches in length as adults. Imagine seeing one of these as a little hatchling barely an inch in length!
- Turtles and tortoises are truly marvels of evolution. Their shells are considered the most important adaptation. The top of a Chelonian's (that's what us turtle nerds call all turtles and tortoises) shell is called the carapace, the bottom is the plastron, and the sides that connect the top and bottom are the bridges.
• The shell is composed of hard, bone plates covered by scutes. The scutes are made of keratin, the primary substance in our own hair and nails. The pigment melanin, present in the scutes, forms intricate designs and brightly colored patterns in some species.
• As a defense mechanism, a typical land turtle or tortoise draws its head, tail, and legs into the shell for protection. The stout, scaly legs form an armored wall for the shell openings. Other turtles, such as the freshwater box and mud turtles, can shut up their shell completely. The plastron (bottom shell) of these turtles is hinged and, when closed, fits firmly against the carapace (top shell).
• Although the shell provides protection, there are many health implications associated with shell anatomy. For instance, if the outer keratin is breached by infection or injury, the turtle can lose its protection and infection can proceed into the bony layer and the body cavity, threatening the turtle's life.
• The shape of the shell will also give you some insight into the animal’s lifestyle and habitat. A high domed shell usually means it's a land dwelling tortoise, with one notable exception, the pancake tortoise of Africa. This tortoise has a flat flexible shell so it can hide in rock outcroppings to avoid predators.
• A smooth, streamlined shell design belongs to sea and freshwater turtles. On land these turtles move awkwardly, but once they are in the water they become incredibly agile and graceful.
• Not all turtle shells are hard, in fact some are quite flexible! The aquatic soft shell turtles from North America, Asia, and Africa all have a leathery skin covering their shells and the edges are pliable. These are some of the fastest turtles on earth when it comes to swimming!
EGGS & REPRODUCTION
- All turtles lay eggs. Some have hard porcelain like shells, while others lay leathery-shelled eggs. After mating, females will seek out a quiet and safe place to lay them. She can be very selective in regards to a nest site. Once she finds the best spot, she will begin the laborious process of excavating the nest. She uses her hind legs to carefully make a flask shaped hole in the ground. Once she has done this she begins to lay her eggs. Some sea turtles can lay over 100 eggs! Larger tortoises will lay up to 50, but smaller turtles and tortoises usually lay between 2-10 eggs. After the eggs have been laid, the mother then covers the nest and leaves. Only one species of tortoise, the Black Mountain Tortoise of South East Asia, stands guard over their nests.
• Some eggs will hatch in as little as 60 days, while others like the Desert Tortoise, take 150 days!! Slow and steady indeed! Another interesting fact about turtle and tortoise eggs is Temperature Sex Determination. If the eggs are incubated at higher temps then most of the babies will be female, lower temps produce males, and in the middle of incubation temps will produce a more even number of males and females.
• Unfortunately, most turtle and tortoise nests are destroyed by predators within the first 48 hours of being laid. Buts it's when they hatch that the real fight for survival begins! Only one percent of the offspring will make it to adulthood. Most are eaten by birds, raccoons, large fish, small mammals, insects, crabs and opossums...everybody in the animal world likes the taste of turtles!
• If the baby is strong and lucky it will grow into an adult that will live to reproduce, creating future generations of turtles and tortoises. Most adult turtles and tortoises are rewarded for reaching adulthood by being among the most long-lived, air-breathing vertebrates on the planet. Ages of more than a hundred years old are common, and one Aldabra tortoise, Adywata in India, was said to be 255 years old!!
What’s the difference between TURTLES & TORTOISES?
Although they appear to be very similar, there are a number of important differences, which set these shelled creatures apart.
Spend most of their lives in the water and have webbed feet for swimming. Sea turtles for instance almost never leave the ocean, except to come ashore to lay eggs. Other turtles live in fresh water ponds and lakes. They swim, but they also spend a considerable amount of time on shore banks or rocks to bask in the sun. In cold weather, they may burrow in the mud, where they go into torpor (a state of decreased physiological activity in an animal, including a usually reduced body temperature and metabolic rate) until spring and warmer weather returns. One species, the Eastern Painted Turtle from North America holds the record in the animal kingdom for holding it's breath. While hibernating under the ice in winter, this turtle may not take another breath for six months!!! It does this by absorbing oxygen from the water through tiny blood vessels in it's throat and Cloaca (the opening, or vent at the base of the tail).
These animals cannot swim, they are land-dwellers that eat shrubs, grasses, and cactus. Tortoises do not have webbed feet, instead their feet are round and stumpy for walking on land. Tortoises living in hot, dry habitats use their strong front legs to dig burrows. Then, when it’s too hot in the sun, they can cool off underground.
There is also another shelled species known as the Terrapin
These animals split time both on land and in water, and always live in areas near water, like rivers, ponds, and lakes. Terrapins are often found in brackish, swampy areas.