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Gregory R. Mann, Ph.D. {ret.}

American Crocodile

“Crocodylus acutus”

American Crocodiles are a shy and reclusive species. They live in coastal areas throughout the Caribbean and occur at the northern end of their range in south Florida. They live in brackish or saltwater areas and can be found in ponds, coves and creeks in mangrove swamps. American Crocodiles are occasionally being encountered inland in freshwater areas of the SE Florida coast as a result of the extensive canal system. Like the American Alligator, American Crocodiles are ectothermic, meaning they rely on external sources of heat to regulate their body temperature. Crocodiles control their body temperature by basking in the sun or moving to areas with warmer or cooler air or water temperatures. A basking American Crocodile may be surprised by an approaching person and quickly (and noisily) enter the water. This behavior might startle the person, but it should not be misunderstood. American Crocodiles would normally enter the water quietly; splashing away indicates that the crocodile is frightened. They can also be seen sunning with their mouths open or “gaping”. This behavior is also related to regulating their body temperature and does not mean that the American Crocodile is acting aggressively toward people. American Crocodiles and American Alligators belong to a group of reptiles called crocodilians, which are the largest of the living reptiles. Of the 23 different species of crocodilians in the world, 2 species are native to the United States and south Florida is the only place where both of these species coexist. The American Alligator ranges throughout the southeastern United States and exist at the southern extreme of their range. American Crocodiles on the other hand, inhabit coastal areas of south Florida where they are at the northern extreme of their range. American Crocodiles also can be found on the islands of Cuba, Jamaica and Hispaniola as well as along both coasts of southern Mexico and Central America, south to Ecuador on the Pacific coast of South America and Venezuela on the Atlantic coast.

At first glance, American Crocodiles can be difficult to distinguish from the American Alligator, but closer inspection reveals several important differences. The American Crocodile is lizard-shaped with a long, muscular tail and four short legs that have five toes on the front feet and four on the back feet. Adults have grayish-green backs and tails and white to yellowish undersides. Their narrow snout is triangular in shape, and the fourth tooth on both sides of the lower jaw is visible when the mouth is closed. The ear drums are protected by movable flaps of skin at the top of the head behind the eyes and the nostrils are at the end of the elongated snout. Because of the location of the eyes, ears and nostrils, an American Crocodile can be submerged with only the top of its head exposed and still be able to see, hear and breathe. Males are larger than females and can reach about 20 feet in length but rarely exceed 14 feet in the wild. Breeding females are about 8 to 12 feet in length. An American Crocodile will eat almost anything that moves. Hatchlings and the young eat small fish, snails, crustaceans, and insects. Adults feed mostly at night on fish, crabs, turtles, snakes, and small mammals. The growth rate of American Crocodiles varies with food availability and temperature. Digestion is efficient only within a certain range of body temperatures. Generally, they grow more slowly near the limits of their range. American Crocodiles build nests that are either holes in or mounds of sand and other earthen material. Unlike birds and mammals, the sex of embryos is not determined at fertilization but by the temperature at which the eggs are incubated. Temperatures of 88 to 91 degrees Fahrenheit produce mostly male offspring and temperatures lower than 88 degrees result in mostly female American Crocodiles. However, the temperature must remain above 82 degrees for the eggs to survive and hatch. Females lay from 20 to 60 eggs per clutch and incubate the eggs for about 85 days until they hatch in late July or early August. Females build soil nests on elevated, well-drained sites. Nests are constructed so that the eggs will be above the high-water mark because American Crocodile eggs cannot survive flooding for more than 12 hours. After nest construction, the female may not remain near the nest; however toward the end of incubation, females visit the nest with increasing frequency. When hatching begins, the mother digs open the nest and may help some of the hatchlings emerge from their eggs. She may also assist the newly hatched American Crocodiles to water or nursery sites where they are released. Adults leave the nesting areas within a day or two, leaving the hatchlings on their own. The hatchlings rapidly disperse from their nest and fend for themselves. American Crocodiles typically live to an age of 50 to 70 in the wild.

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