Florida s Amazing Fresh Water Turtles

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1 Florida s Amazing Fresh Water Turtles Did you know that turtles are amongst the most ancient of all the animal species on Earth? They are believed to have originated as far back as million years, more ancient than lizards, snakes, crocodiles and even the oldest dinosaurs. Great mystery surrounds the evolution of turtles. Turtles first appear in the fossil records as turtles, not that different in appearance from turtles of today (the first turtles had teeth and could not retract the head into the shell). Intermediate fossil evidence to help explain which species turtles originated from are lacking although recent fossil evidence was uncovered in southwestern China of a turtle without a fully developed carapace (top shell). A recent genetic study suggests the turtle is most closely related to birds and crocodilians and not lizards and snakes. For more information on the evolution of turtles, search the Internet under the heading, evolution of turtles. Turtles are reptiles and have to use their environment to manage their body temperatures; what most people call cold-blooded and what scientist call ectotherms. This is why you see turtles basking in the sun often with all four legs and head outstretched. Turtles are the only vertebrates (animals with a backbone) to have the entire skeleton inside a solid boney armor. The top shell of a turtle is called the carapace, and the bottom shell a plastron, and the two are connected by supports called bridges. A turtle s spine is fused to the inside of its carapace, so no turtle can leave its shell, nor can any turtle live once removed from its shell. Did you know that turtles have great night vision and see in color? They also have an excellent sense of smell. They do however have a poor sense of hearing (feel low frequency vibrations) and are virtually mute although they can make guttural sounds at times. While turtles don t have teeth they do have a beak and their jaws have horned ridges, which have basically the same function as teeth. Fresh water turtles can hold their

2 breath under water for quite some time. It depends on the species, size, and activity but for the most part, active turtles can spend 20 minutes underwater and resting turtles up to 2 hours. Some turtle species hibernate and spend up to 4 months under water. They can slow their heartbeat to 5-10 beats per minute and can absorb oxygen through certain parts of their body. Researchers have recently discovered a turtle s organs do not gradually break down or become less efficient over time, unlike most other animals. It was found that the liver, lungs, and kidneys of a centenarian turtle (over 100 years old) are virtually indistinguishable from those of its immature counterpart. This has inspired genetic researchers to begin examining the turtle genome for longevity genes. Turtles occur on all continents except Antarctica. Typically, turtles range throughout the tropical and warm temperate regions of the world, occupying a wide variety of habitats, from rain forest to true desert, from small puddles to great rivers and lakes, and playing diverse ecological roles. There are approximately 300 species of turtles in the world with roughly 200 of those species being fresh water turtles. Land-based turtles are called tortoises and live in an ecosystem of forests, deserts and grasslands. Aquatic, water-based turtles live in swamps, ponds, freshwater lakes, streams and oceans. Marine-based turtles are known as sea turtles. Virtually all reptiles lay eggs and turtles are no exception (there are a very few snake species and even fewer skink species that give birth to live young). Many of the freshwater species will exit the water and travel a distance from their home body of water in order to lay eggs. This can be quite hazardous for the turtles especially if there are roads to cross or excessive predators. The selected nest site is usually on a sunny, southern slope so that the eggs may be warmed by the sun. Turtles also look for a site that has minimal grass or vegetation to allow for more sun exposure to the nest. A hole is dug; the eggs are laid and then covered with soil or leaf litter. Temperature plays an important role in determining the sex of turtles. Warmer temperatures produce females and cooler temperatures produce male offspring. When the turtles hatch, they squirm their way to the surface and head toward the water. There are no known turtle species in which the mother cares for the young. Turtles are very beneficial and have been used as biological indicator species. Biological indicators are species that can be used to monitor the health of an environment or ecosystem. Turtles (often turtle eggs) have been used to detect radionuclides, selenium, arsenic, lead, mercury, cadmium, strontium, polychlorinated dioxins, PCB s, organochlorides, and new chemicals from flame retardants, polybrominated diphenyls. These toxins tend to accumulate in their eggs, bones, tissue and/or shell. All turtles play crucial roles in their ecosystems because turtles are omnivores and feed on animals and plants. Turtles also provide seed dispersal, vegetation management, insect and snail control, nutrient cycling, and keep water clean (by scavenging dead animals and preying on weak or sick individuals). Turtles (eggs and young) are a food source for larger predators. Typically freshwater turtles eat aquatic insects, snails, vegetation, tadpoles,

3 crayfish, fallen fruits, various seeds and occasionally small fish (usually diseased and/or weakened). Some turtle species consume algae that could deplete oxygen from the water if grown without control. Turtles are seldom a pest to people. Turtles are very beneficial and of economic importance, except in certain areas such as waterfowl sanctuaries, aquaculture facilities, and rice fields in the south. Indiscriminate destruction of turtles is strongly discouraged. It is important that turtle populations are not depleted, but rather maintained within their natural habitats. Unfortunately turtles are facing many pressures across their range. Florida, excluding the sea turtles, has 26 species of turtles and 18 of those are fresh water species. Three are listed as threatened or endangered (again excluding sea turtles). One of the most intense pressures comes from the commercial trade. Turtles of the United States are caught in large numbers to be sold as food or as pets. They are sought for export to the Asian food and traditional medicine markets and run the risk of being over-harvested. Another impact on turtle populations is roadways. Turtles, especially during the warmer months, are more active and will travel across roads and other man made paths to find suitable nest sites. This activity puts turtles at risk of being hit by vehicles, not only harming the traveling individual but also the eggs it may be carrying. Typically, overharvesting for food and trade has been the primary cause of species decline, and then habitat destruction- but sometimes vice-versa. Because of these threats the Florida Fish and Wildlife Conservation Commission (FWC) has recently approved strong conservation measures for Florida s turtles. The following species are prohibited from taking because they are imperiled; alligator snapping turtle, Barbour s map turtle, and Suwanee Cooter. There are three look-alike species that are prohibited as well; snapping turtles, Escambia map turtle, and any cooter species. If you are interested in the current rules and regulations please visit Other Interesting Chelonian Facts Chelonian refers to turtles not the monsters from Doctor Who. * Some turtles, such as the Musk turtle, emit an odor when startled. * Some turtles can live a year without food. * Turtles shed their skin in small flakes.

4 * Alligator snapping turtles have tongue lures. * Earliest turtles had teeth and could not retract their heads. * Sea turtles have special glands which help remove salt from the water they drink. * One species of turtle in Australia lays its eggs underwater and they begin to develop when the water recedes. * The blood of hibernating turtles acts somewhat like antifreeze, allowing it to tolerate cold temperatures. * Some female turtles produce eggs four years after mating. * All turtles lay their eggs on land. * Hatching turtles have an egg tooth at the end of their beak to help open the egg. * Some land turtles can out run a human. * The smallest turtle, the Speckled Padloper is 4". The largest is the Leatherback sea turtle that can reach up to 10' in length. * Turtle shells DO break. * Sea turtles can migrate over 10,000 miles and have the equivalent of built in GPS units. They can detect latitude which is the north-south placement on the planet and they can detect longitude which is the east-west placement on the planet. * The color and patterns of each species allows them to blend into their natural environment. * Turtles can regrow bony and keratin tissue. * Not all turtles have hard shells. For example, Softshell turtles and sea turtles have flexible shells. * Box turtles are not the only turtles with a hinge to allow part of their shell to move. * The top shell, the carapace, is made up of approximately 50 bones. * Counting the growth rings on the scutes (scales) of the top shell does not tell the age of the turtle or tortoise. * Some turtles have hinges on their shells to enable them to close up tightly inside.

5 * Turtles cannot protrude their tongues from their mouths. * Aquatic turtles have streamlined shells to help them move through the water. They also have webbing between their toes. * Aquatic turtles must be in water to eat. * Tortoises only go to water to drink. They do not swim. * Some tortoises can dig burrows 45 feet long. * Many turtles are expert climbers. * Land turtles ears are sensitive to ground vibration. * A group of turtles is classically called a bale. * One of the most common health problems is MBD, Metabolic Bone Disease, caused by improper diet and care. * All turtles and tortoises do not have the same habitat and nutritional requirements. * Turtles have good eyesight, seeing in full color and a strong sense of smell. Some have excellent hearing and sense of touch. Their shells have feeling due to nerve endings. * Some turtles can live up to a year without food. * Tortoises from dry environments have thick scales on the skin to prevent fluid evaporation. Aquatic and semi-aquatic turtles have thinner skin and lack heavy scales. * Turtles shed their skin in small flakes rather than pieces like other reptiles. * Some sea turtles can swim up to 35 mile per hour. * Several species, including the American Box turtle, can live to be over 100 years old. * One documented case of longevity is of an adult Indian Ocean Giant Tortoise. After being captured and estimated to be 50 years old, it lived another 152 years in captivity.