When you hear about an alligator or crocodile, what do you picture in your mind? Ferocious man-eaters? Cute cuddly cartoon creatures? Well, while these reptiles are definitely not cuddly, they are not as fearsome as one might think. Come with us while we learn all about these fascinating animals. The Crocodilian Family The Family Crocodylidae includes alligators, caimans, gavials, and crocodiles. This family has existed since the upper Triassic period, over 200 million years ago. Animals that can definitely be classified as modern crocodilians began to appear in the fossil record about 80 million years ago. Today, Family Crocodylidae has three subfamilies: Alligatorinae: alligators and caimans Crocodylinae; crocodiles Gavialinae: gavials also known as gharials Today there are twenty-three known living crocodilian species. They are found in over ninety countries and islands. Their habitats are generally in tropical regions, crocodilians cannot survive and reproduce in cold climates. The American and Chinese alligators are the most cold tolerant, and have been found in ice in the northern most areas of their ranges. What Do Crocodilians Eat? All varieties are nocturnal and feed mostly at night. They are carnivorous and, with some variation, will eat fish, turtles, birds, crustaceans, mammals, snakes, frogs, and on occasion, young crocodilians. The exceptions to this are the gharials, which eat only fish. These animals swallow their prey whole; their conical-shaped teeth are for grabbing and holding, not for cutting. Crocodilians have from between 75 to 80 teeth. If a tooth is lost it will be replaced. Their jaws can exert a tremendous amount of pressure. They do not tear their prey apart, although an animal may shake its head or spin its body to tear off a chunk of meat if it is too large to swallow whole. They may also hold the food in their mouth until it decays enough to swallow. Crocodilians have a specialized valve in their throats called a glottis that enables the animal to catch its prey while underwater and not drown. It still must lift its head above water to be able to swallow its prey without drowning. Crocodilian stomachs have two chambers; the first grinds up its food while the second is the digestive system that extracts nutrients from the food. Crocodilians have the most acidic digestive system of any animal and it can digest bones, hooves, and horns. However, items such as sticks, rocks, cans, and fishing lures cannot be digested. All of these have been found in the stomachs of alligators. Are All Crocodilian Man Eaters? Only two species of crocodiles, the Nile and the Salt Water, are considered man eaters. Most have a natural fear of humans and would rather stay away than attack. There have been alligator attacks on humans, mainly on children and swimmers, and are considered to be caused by human error. These creatures are extremely quick and agile and are capable of amazingly fast bursts of speed, if only for a short distance. Caution should be exercised around these animals. They are not domestic and can inflict serious injury. Crocodilians will attack in self defense, to obtain food and to protect their young. A good rule is - if you see one of these creatures in the wild LEAVE IT ALONE!!! Crocodilians are Well Suited to Spend Time in the Water While the exact habitat may be different for each type of crocodilian, all modern ones spend a great deal of time in the water. All have strong tails that propel them forward when swimming. The front feet have sharp claws used for traction and catching prey while the hind feet are webbed, allowing for better balance on land and improved maneuverability when moving very slowly through the water. At faster swimming speeds, they fold their legs straight back and simply use their powerful tail. Their nostrils are located on the top of their snout, allowing them to breathe while almost completely submerged. Crocodilians have good eyesight and hearing. They have a well developed inner ear and have a movable flap covering their external ear to prevent water from coming in. Crocodilians may be able to see colors and use sight to catch prey above water. It is a different story under water. They aren’t able to focus as well and they have a protective third eyelid, called the nictitating membrane. This membrane is not completely transparent, so when underwater, the animal must use its other senses, including the ability to detect pressure changes around the jaw. There are small sensory pits dotted around the upper and lower jaws called DPRs or Dermal Pressure Receptors. Crocodiles have these receptors covering their entire body while alligators and caimans have them only around the jaw. These DPRs are capable of detecting small pressure changes in the water and help the animal find and capture prey. Skin Coloration Provides Camouflage Crocodilians have a thick layer of skin covered with interlocking plates called scales and within the skin bony buttons or plates, called osteoderms, create an armor for protections. While coloration among the species can vary, its coloration allows it to blend into its environment, providing camouflage for protection. Most Vocal of All Reptiles Crocodilians are the most vocal of all reptiles and their calls vary widely depending upon species, size, age, and sex. Content is also very important and some species can communicate over twenty kinds of messages through sound alone. Size and Growth Rates Size and growth rates vary among the species and according to the conditions under which they are raised. Optimum growth is reached at a temperature of 89 ° F and with a steady, adequate supply of food. Under ideal conditions a juvenile can grow about one foot per year. Growth rates slow down in adults. Crocodilians are Outstanding Parents Among the reptiles, crocodilians are outstanding parents. The mother builds a nest of sticks, mud and vegetation in which to lays her eggs, up to 60 depending upon the species. The decaying vegetation keeps the eggs warm while the mother stands guard. The temperature of the egg determines the gender of the hatchlings. Crocodilians have no sex chromosomes. Low or very high nest temperatures will produce females while intermediate temperatures favor males. The gestation rate varies among species. The hatchlings emit a high pitched noise to alert the mother who uncovers the nest and releases the babies. The hatchlings head for the water and some females have been known to carry their babies to the water. The female stays with her babies until the next laying season, guarding them against predators. The first few years are the most dangerous. Baby crocodilians have many predators, including snakes, wading birds, osprey, raccoons, otters, large bass, garfish, and even larger crocodilians. After the reptile reaches about four feet, man and other crocodilians are its only predator. Endangered Status of Crocodilians All crocodilians are on the endangered species list mainly due to habitat destruction and overhunting. Because of its endangered status, none of these creatures should ever be taken from the wild without proper authorization and due diligence should be exercised when purchasing an imported animal. Laws on private ownership vary from state to state. The alligator alone is a success story. They were hunted almost to the brink of extinction for its skin and meat. The animal has had a dramatic resurgence due to human protection. ALLIGATORS are found today only in the southeastern part of the United States and in the Yangtze River Basin in China. The name comes from the Spanish el lagarto (the lizard), so called by the Spanish explorers who were amazed by this large meat-eating reptile. Alligators live mostly in brackish waters such as swamps, marshes, canals, lakes and drainage canals. They are characterized by their short rounded snouts. Adults are grayish black in color while the young have yellow or white marks on a black body. The American alligator can grow up to 19 feet, the average is between 7 and 15 feet and can weigh up to 1300 pounds. The Chinese alligator is much smaller and only grows to about 6 feet. Alligators can live in the wild 35 to 50 years and up to 80 years in captivity. CAIMANS are a close relative of the alligator and are found primarily in Central and South America. There are many types of caimans, the best known is the Speckled caiman which were often sold in the pet trade as baby alligators. These are normally small and squat with a toothy grin. The Black caiman, found in fresh water habitats in South America, including the Amazon Basin, most resembles an alligator. While the Black caiman can reach 13 feet in length, the average for a caiman is between 4 and 8 feet. CROCODILES are found all over the world and include many species. Crocodiles are characterized by its longer, more pointed snout and by a prominently protruding fourth tooth in the lower jaw. The Mugger crocodile is the exception to this rule, with a wide, broad head. Crocodiles also have a functioning salt gland on their tongue, making them more tolerant of salt water. Most crocodiles are light tan to brownish in color. There is only one type, the American crocodile, found in the United States. It is very rare and is found only in the southernmost part of Florida, Central America and parts of South America. It lives in warm quiet waters, either brackish or salty, like mangrove swamps or estuaries. Adult American crocodiles are gray-green, dark olive, or grayish brown on their backs, which have ridged bony scales. The belly is yellow to white and has smooth scales.