American crocodile

(Crocodaylus acutus)



The American crocodile is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas. Populations occur from the Atlantic and Pacific coasts of southern Mexico to South America as far as Peru and Venezuela. It also lives on many of the Caribbean islands such as Cuba, Jamaica, Hispaniola and Grand Cayman.

Conservation status

Vulnerable



Scientific classification

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Crocodylidae
Genus: Crocodylus
Specie: Crocodylus acutus


Description



Like all crocodilians, the American crocodile is a quadruped, with four short, stocky legs, a long, powerful tail and a scaly hide with rows of ossified scutes running down its back and tail. Its snout is elongated and includes a strong pair of jaws. Its eyes have nictitating membranes for protection along with lachrymal glands, which produce tears.

The nostrils, eyes, and ears are situated on the top of its head, so the rest of the body can be concealed underwater for surprise attacks. Camouflage also helps it prey on food. The snout is relatively longer and narrower than that of the American alligator (Alligator mississippiensis), although broader on average than that of the Orinoco crocodile (C. intermedius). American crocodiles are also paler and more grayish than the relatively dark-hued alligator. This crocodile species normally crawls on its belly, but it can also "high walk". Larger specimens can charge up to nearly 10 mph (16 km/h). They can swim at as much as 20 mph (32 km/h) by moving their bodies and tails in a sinuous fashion, but they cannot sustain this speed.



The American crocodile is sometimes confused with the smaller, Central American Morelet's crocodile, a smaller species that is native to Mexico.

Distribution and habitat

Crocodylus acutus is the most widespread of the four extant species of crocodiles from the Americas. It inhabits waters such as mangrove swamps, river mouths, fresh waters, and salt lakes, and can even be found at sea, hence its wide distribution throughout the Caribbean islands, southern Florida, the Greater Antilles, southern Mexico, Central America, and the South American countries of Colombia and Ecuador. The American crocodile is especially plentiful in Costa Rica. One of its largest documented populations is in Lago Enriquillo, a hypersaline lake in the Dominican Republic. The species has also been recorded from Jamaica. American crocodiles have recently been sighted in Grand Cayman, leading experts to believe the species may be swimming from Cuba (which is home to a massive American crocodile population) and slowly repopulating Grand Cayman. In addition, an American crocodile/Cuban crocodile hybrid was recently discovered in the Cancun area. The crocodile likely originated in the Zapata Swamp of Cuba (the only place where these wild hybrids exist) and swam to the Yucatán Peninsula. Their saline tolerance also allowed the American crocodile to colonize limited portions of the United States (Puerto Rico and extreme southern Florida). Contrary to popular misinformation, the presence of the American alligator is not the reason the American crocodile was unable to populate brackish waters north of Florida, but rather the climate.

American crocodiles, unlike American alligators, are extremely susceptible to cold temperatures and live exclusively within tropical waters. During 2009, unusually cold weather in southern Florida resulted in the deaths of about 150 wild American crocodiles, including a well-known crocodile which inhabited Sanibel Island far north of their natural range.

American crocodiles in the United States coexist with the American alligator, and are primarily found south of the latitude of Miami, in Everglades National Park, Florida Bay, Biscayne Bay, and the Florida Keys. A sizable population occurs near Homestead, Florida, at the Turkey Point Nuclear Generating Station. Some individuals wander northward to warm summer waters and have been sighted in Sarasota County and Palm Beach County. In the summer of 2008, a crocodile was captured in the surf on Isle of Palms, South Carolina. In 2013, a 700-pound crocodile was captured in Tarpon Springs, Florida. Florida Fish and Wildlife Conservation Commission program staff note that the crocodile was not weighed to be 700 lbs. The weight was estimated by the Nuisance Alligator Trapper who inadvertently caught the animal using a baited hook. American crocodiles of similar lengths have been accurately weighed at 450-500 lbs.

The American crocodile is saltwater-tolerant and have thus been capable of colonizing a multitude of islands within the Caribbean islands and on some coastal Pacific islands as well. They coexist with the rather smaller spectacled caiman within Central America. The only other crocodiles present within the American crocodile's range are two species smaller than this species on average: the critically endangered Cuban crocodile, along with the Morelet's crocodile in southern Mexico and Guatemala.

Behavior



American crocodiles are more susceptible to cold than American alligators. While an American alligator can survive in water of 7.2 °C (45.0 °F) for some time, an American crocodile in that environment would become helpless and drown. American crocodiles, however, have a faster growth rate than alligators, and are much more tolerant of salt water.

Cleaning symbiosis involving the American crocodile as client has been described. Unlike the Old World crocodiles, which are sometimes cleared of parasites by birds, the American crocodile relies more on fish for parasite removal.

Reproduction

American crocodiles breed in late fall or early winter, engaging in drawn-out mating ceremonies in which males emit very low frequency bellows to attract females. Body size is more important than age in determining reproductive capabilities, and females reach sexual maturity at a length of about 2.8 m (9.2 ft). In February or March, gravid females will begin to create nests of sand, mud, and dead vegetation along the water's edge. Nest location is crucial, and with the correct amount of vegetation, the eggs will develop within a small temperature range. Because sex determination is temperature-dependent in crocodilians, slight aberrations in temperature may result in all-male or all-female clutches, which would possibly harm the health of the population. About one month later, when it is time to lay, the female will dig a wide hole diagonally into the side of the nest and lay 30 to 70 eggs in it, depending on her size. After laying, the female may cover the eggs with debris or leave them uncovered. The white, elongated eggs are 8 cm (3.1 in) long and 5 cm (2.0 in) wide and have a number of pores in the brittle shell. During the 75- to 80-day incubation period, the parents will guard the nest, often inhabiting a hole in the bank nearby. Females especially have been known to guard their nests with ferocity. But in spite of these precautions, crocodile eggs sometimes fall prey to raccoons (Procyon sp.) (arguably the most virulent natural predator of crocodilian nests in the Americas), coatis, foxes, skunks or other scavenging mammals (even coyotes (Canis latrans) in Mexico and American black bears (Ursus americanus)) in south Florida), as well as large predatory ants, crabs and vultures. In Panama, green iguana (Iguana iguana) were seen to dig up and prey on American crocodile eggs occasionally, although in several cases were caught by the mother crocodile and subsequently consumed. Crocodilian eggs are somewhat brittle, but softer than bird eggs. Young of this species hatch after 75-80 days.

This species exists mostly in tropical areas with distinct rainy seasons, and the young hatch near the time of the first rains of the summer (July-August), after the preceding dry season and before the bodies of water where they live flood. In this stage of development of their young, mother crocodiles exhibit a unique mode of parental care. During the hatching process, when the young crocodiles are most vulnerable to predation, they will instinctively call out in soft, grunt-like croaks. These sounds trigger the female to attend to the nest, uncovering the eggs if they have been covered. Then she will aid the hatchlings in escaping their eggs and scoop them up with her mouth, carrying them to the closest water source.

The hatchlings, which are 24 to 27 cm (9.4 to 10.6 in) in length, have been reported to actively hunt prey within a few days of hatching. It is not uncommon for the mother to care for her young even weeks after they have hatched, remaining attentive to their calls and continuing to provide transportation. About five weeks after hatching, the young crocodiles disband in search of their own independent lives. Most of them, of course, will not survive, being preyed upon by several types of raptorial birds and larger fishes (e.g. barred catfish (Pseudoplatystoma fasciatum), Atlantic tarpons (Megalops atlanticus), common snook (Centropomis undecimalis) and lemon sharks (Negaprion brevirostris)), boa constrictors (Boa constrictor), black spiny-tailed iguana (Ctenosaura similis), spectacled caimans, as well as raccoons. Those that do survive the early stages of life will grow rapidly, feeding on insects, fish and frogs. Additionally, some young crocodiles reportedly will feed on each other.


Zoológico de Vallarta A. C.

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