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American Crocodile (American Saltwater Crocodile, South American Alligator)


Image (c) Adam Britton, crocodilian.com

Will vomit up food to attract fish


Order: Crocodylia

Family: Crocodylidae

Subfamily: Crocodylinae

Genus & Species: Crocodylus acutus

APPEARANCE

The American crocodile is perhaps one of the largest species of crocodiles. They average at 12 ft (3.5 m) in length, with a maximum length of 23 ft (7 m) longer than the infamous Nile crocodile. The males are larger than females, and weigh an average of 500-1000 lbs (220-450 kg). The tail is long and powerful. They are basically lizard-shape in appearance, with four squat but powerful legs ending in sharp claws. The snout is long, narrow, and triangular in shape. The nostrils are located on the end of the snout. The eyes are on the top of the head and have a nictitating membrane (extra eyelid) which allow them to see underwater while protecting the eye. The area around the eyes of mature American crocodiles have a distinct swelling. The eardrums are located behind the eyes and are covered by a movable flap of skin. The eyes, ears, and nostrils are all located on the same plane. The eye's iris is silvery and the pupil is a vertical slit which allows good vision at night. American crocodiles have a four-chambered heart like birds.

American crocodiles have conical, pointed teeth on the top jaw which interlock with those on the bottom jaw. These teeth are used primarily for grabbing and tearing, not chewing and cutting. The fourth tooth on either side of the bottom jaw is larger than the other teeth and can be seen while the jaw is closed.

American crocodiles are not the traditional green in colour. Rather, they are tan grey or olive grey with darker markings. The belly is white or yellowish. Juveniles have dark cross-bands on the back and tail which disappear with age. All ages have backs that are sporadically covered in a bony armour made up of plates called osteoderms. These plates are more reduced in the American crocodile than in other species.

HABITAT

American crocodiles are found in the souther tip of Florida, including the Florida Keys. They are also found in Central and South America and the West Indies, including Belize, Colombia, Costa Rica, Ecuador, El Salvador, Venezuela, Peru, Panama, Mexico, Guatemala, Nicaragua, Martinique, Margarita, Dominican Republic, Haiti, Cuba, Honduras, Hispaniola, Jamaica, and Trinidad.

American crocodiles prefer saltwater, and are found primarily in saltwater swamps and marshes, sometimes swimming into the ocean. They can also be found in freshwater. They dig burrows to escape the heat of the summer, and will travel long distances on land if their waterhole dries up. They are active at night, basking near the water during the day.

FOOD

American crocodiles have a slow rate of digestion during the cold weather, allowing them to go for months without food. The larger crocodiles feed primarily on small mammals, birds, fish, and crabs. The juveniles feed on insects, snails, frogs, small fish, and crabs. American crocodiles will also eat carcasses. They have been known to attack humans and can be cannibalistic.

American crocodiles hunt by remaining completely motionless in the water. When prey is close enough, they attack, grabbing the animal and drowning it. They may also regurgitate bits of food to attract fish. American crocodiles swallow stones to aide in digestion and to help stabilize them in the water.

ENEMIES

The American crocodile has few enemies. The smaller ones are sometimes attacked and killed by the larger ones. Humans are their main threat, having hunted them from 1930-1960 for their skin. Today, hunting is less of a problem as they are protected, but habitat loss from dams, fishfarms, and the evergrowing human population are an imminent threat. They are considered to be endangered. The largest population is found in the Dominican Republic, with 200 mature American crocodiles

BREEDING

American crocodiles reach sexual maturity at 8-10 years of age or 6-8 ft (1.8-2.4 m) in length. The breeding season is between January and May. Courtship can last for two months, after which the 20-60 eggs are laid in a hole or mounded nest. The eggs are 24-31 in (60-77 cm) in length and are protected by a tough and leathery shell. They are covered with sand and left to incubate for 90 days by the heat of the sun. The parents vigorously defend the nest during this time. When it is time for them to hatch, the female digs and helps them out of their nest. She then takes them to a nursery site along the water and then abandons them. The hatchlings can fend for themselves from birth.

RELATIVES

There are 23 species of crocodilians found worldwide. The American crocodile shares its habitat with the American alligator and the Cuban crocodile.

RESOURCES CITED

1. "American Crocodile" Animal Card, Italy, 1977
2. "Crocodile" Funk & Wagnall's Wildlife Encyclopedia, pg 553, vol 5, 1978, BPC Pub Ltd, NY
3. www.phillyzoo.org/pz0176.htm
4. www.shadow.net/~grgreen/glades/croc.html
5. www.co.miami-dade.fl.us/derm/Crocodile.htm
6. www.bio.bris.ac.uk/research/crocs/csp_cacu.htm (cached at www.google.com)
7. www.nrca.org/biodiversity/Species/crocodile.htm

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