The American crocodile, scientifically known as Crocodylus acutus, is the second most widely distributed species among New World crocodiles. It can be found in various locations including the southern tip of Florida, the Atlantic and Pacific Coasts of Southern Mexico, and the Caribbean islands of Cuba, Jamaica, and Hispaniola. These regions offer an ideal climate for this endangered species that has existed on Earth for over 200 million years.
In Florida, there is a significant population of American alligators often mistaken for the rare American crocodile. However, it is important to understand that these two species have notable differences. Unfortunately, hunting for their hides and converting their habitat into beachfront properties are serious threats to the American crocodile population in Florida. Consequently, they are gradually being displaced from their sole habitat within the United States.
Crocodilians have been present in rivers, lakes, swamps, and estuaries for 190 million years and are the remaining survivors of the once dominant reptiles that inhabited Earth for over 200 million years. However, it is incorrect to view crocodilians as living fossils confined to a marginal ecological niche. They have evolved significantly throughout their extensive evolutionary history to adapt to their specialized way of life.
Despite existing for millions of years, crocodilians have undergone relatively few changes since their appearance around 200 million years ago, which demonstrates their success. The Crocodile belongs to the Crocodylinae family that also includes alligators, gharial, and other types of crocodiles. These organisms possess common traits characteristic of the crocodilian group.
Although birds rather than lizards are the closest relatives of crocodilians among living vertebrates, they share certain characteristics such as an elongated outer ear canal, a muscular gizzard, and complete separation of heart ventricles. Crocodilians are considered advanced reptiles with a lizard-like body shape that is elongated and armored. Their laterally shaped tail enables swimming while their elongated snout with end-set nostrils allows them to breathe underwater.
The American alligator (Alligatorinae mississippiensis) and the American crocodile are frequently confused, but they are part of the same family. However, they have noticeable differences. An important distinction is their snout shape—the alligator has a wider snout while the crocodile has a narrower one, suggesting a preference for fish as food. Furthermore, only the American crocodile has front two teeth that grow upwards and penetrate the upper jaw from below; this characteristic is not present in alligators. These teeth serve as a crucial distinguishing factor between crocodiles and alligators.
The American crocodile and alligator have a not so apparent difference concerning the regulation of saltwater balance in their bodies. The crocodile is able to maintain salt concentrations at the typical level of other vertebrates, which is around one-third of seawater. The challenges faced by osmoregulation in fresh or saline waters are connected to the exchange of water and salts through various bodily surfaces. Salt and water are lost through feces, urine, respiration, excretion from salt glands in the tongue, and the skin. The American crocodile’s ability to tolerate saltwater is linked to their low rate of water loss and sodium uptake, their capability to excrete excess sodium, and their regular behavioral osmoregulation by avoiding drinking saline water or seeking fresh water after feeding in areas with high salinity. It is worth mentioning that the American crocodiles will not drink seawater even when dehydrated, unlike the American alligator which can, although it lacks the ability to excrete excess sodium.
The American Crocodile is capable of regulating its salinity but cannot maintain a constant body temperature. Similar to all reptiles, crocodiles are cold-blooded or pokilothermic. They utilize a combination of physiological and behavioral mechanisms to keep their body temperature stable. To warm up, they rely on solar radiation, basking in shallow waters or on shorelines as they emerge from the water. When their temperature rises, they open their mouths to allow for evaporative cooling. The membranes in their mouth cavity play a crucial role in temperature regulation. Crocodiles may also partially bask in the sun with their tail or head in water to adjust their temperature optimally. Additionally, they can adjust body temperature by redirecting blood flow towards or away from their surface. The animal constricts its superficial blood vessels to limit heat loss and maintain a steady core temperature as it cools down. Mud bathing serves as another temperature-regulating strategy, providing an extra layer of insulation against extreme environmental temperatures.
The American crocodile is found in subtropical to tropical areas where it can regulate its body temperature optimally. It is an estuarine species that can migrate through salt water. According to Guggisberg (40), it can be found in various regions, including Equador, the Pacific Coast to western Mexico, and from eastern Mexico to Guatemala, as well as coastal areas of Colombia and Venezuela, and the Caribbean to the southernmost tip of Florida. Ross (65) states that this species commonly resides in coastal habitats, large rivers, and lakes within its range. It has also been observed in freshwater areas like reservoirs (1). In Florida, C. acutus can be found in mangrove swamps and saltwater marshes with sandy, undisturbed high spots (10B). The northern end of their range is South Florida, historically extending from Cape Sable to Lake Worth in Palm Beach County, and fewer numbers up to Sanibel on the west coast. However, due to habitat destruction, their range is now limited to undeveloped areas from Cape Sable to North Key Largo and Turkey Point (6H).
The American crocodile was listed as endangered in 1975 due to extensive overexploitation from the 1930s to the 1960s, driven by the high value of its hide (1 Species). Most populations of C. acutus are heavily hunted, with only a few adequately protected in national parks in Costa Rica, Venezuela, and the United States (226 Ross). Historically, crocodilian skin was highly valued for its quality, flexibility, and decorative appearance when processed. This led to trafficking in crocodilian skins becoming a lucrative business and resulting in a wide range of expensive leather products. In the early 1900s alone, US tanneries processed between 250,000 and 500,000 skins annually. Despite protective laws being enacted later on, profit incentives led to widespread poaching and smuggling of illegal skins via middlemen supplying tanneries and leather markets. As a result of this rampant hunting by the mid-1960s, many crocodile species were critically threatened or approaching extinction. Today’s global market for crocodilian skins is approximately two million hides per year. Some skins come from controlled hunting with licenses while others are harvested from captive populations on farms and ranches. However, according to Levy (102), these skins are considered illegal as approximately one million hides are obtained from poachers each year.Furthermore, the decline of crocodile populations is greatly influenced by habitat destruction and motor vehicles in inhabited areas.
The American crocodile was almost extinct in the United States in the 1970s. However, there is now a well-protected population of crocodiles in southernmost Florida. The natural landscape changes initially limited their habitat, but it now supports about 500 crocodiles. State and federal agencies, as well as the nuclear power industry, have helped protect their habitats. At South Florida’s Turkey Point nuclear power plant, endangered crocodiles have increased in number and successfully bred in a network of mangrove-lined cooling canals stretching 168 miles.
The nuclear power plant at Turkey Point was initially opposed by environmentalists because they believed it would harm seagrasses in Biscayne Bay. To address this concern, the Power company constructed cooling canals to cool the water before returning it to Biscayne Bay. The excess sand from the canal construction created an ideal nesting habitat for crocodiles. The Florida Power and Light Company has invested money in crocodile research efforts and decided against expanding the power plant, ensuring the safety of the crocodile habitat. Crocodiles, once confined to a small area due to development, are now reproducing at a rate that allows them to roam more freely along the South Florida coast. This increase in available nesting locations has played a pivotal role in their population recovery, with nest numbers rising significantly over time.”Despite none of the eggs hatching, the discovery of a clutch of eggs on Sanibel Island in 1995 was seen as a hopeful sign for researchers. Nesting is considered a reliable indicator of crocodile recolonization. In [1993], Turkey Point had an impressive year with the discovery of 12 nests and 155 hatchlings. Similarly, in [1994], they recorded nine nests and 153 hatchlings during the hatching period.”
Crocodiles lay their eggs on land in exposed locations, usually within 30 feet of the water. The nests consist of sand, earth, and a significant amount of plant material like grasses, water reeds, and leaves. As the plant material decomposes, it emits heat to provide insulation for the eggs. Using its hind feet, the crocodile digs a hole and uses the excavated soil to partially cover the eggs. The crocodile species that nests in mounds collects leaves, grasses, reeds, and other plant debris at the chosen nesting site. It then combines this material with earth or sand to construct a mound. After forming the mound, the mother crocodile compresses all materials to create a solid structure. Lastly, she creates a cavity up to two feet deep where she lays her eggs before covering them.
Temperature-dependent sex determination (TSD) is a crucial factor in determining the hatchling sex of crocodilians. This phenomenon has been confirmed in five species of crocodiles and is believed to be applicable to all species because crocodilians lack sex chromosomes. Only females are produced at low incubation temperatures, while intermediate temperatures result in the production of males. High temperatures tend to produce mostly or exclusively females.
The sex ratio of offspring is significantly affected by the location and timing of nest construction by the female. Thermal cues likely play a major role in selecting and constructing nest sites, leading to nests with all siblings being of the same sex. The critical period of thermal sensitivity starts early in development and lasts throughout the first half of incubation (Ross 120).
Unbeknownst to them, FPL unintentionally created prime nesting sites for crocodiles (Miller 1E). Key breeding areas for C. acutus include Turkey Point’s cooling canals, Everglades National Park, and Key Largo.
“As American crocodiles can generate valuable hide for commercial purposes, it is possible to implement sustainable utilization programs through ranching and farming. Nonetheless, the establishment of such programs must be tailored to each country and closely linked to the well-being of wild populations. While a majority of the countries where crocodiles live [8 out of 17] have management programs that offer complete protection, only a limited number have effectively enforced legislations. El Salvador and Haiti lack any form of management program. The farming of American crocodiles has commenced in five countries” (3 Species).
In the early 1960s, conservation laws were introduced due to the limited supply of wild crocodiles for the skin trade. This resulted in increased prices and demand for crocodile skins. Forward-thinking conservationists and skin producers took advantage of this situation by considering farming and ranching crocodiles on a sustainable, commercial scale. Conservation and educational farms primarily focus on breeding endangered species like the American crocodile in captivity, with the ultimate aim of reintroducing them into protected areas in their natural habitat. Any commercial development or international trade involving endangered species such as crocodiles must comply with the conditions set by CITES. Commercial farms must show that their harvesting practices do not negatively impact the survival of these species within a specific geographical area.
The preservation of the habitat of the American crocodile is currently a priority given that these crocodiles have been in existence for approximately 200 million years. They can be located in various places including the southern tip of Florida, the Atlantic and Pacific Coasts of Southern Mexico, and Caribbean islands like Cuba, Jamaica, and Hispaniola (1 Species). In Florida, they are frequently mistaken for their more aggressive relative, the American alligator. However, there are notable distinctions between these two species. The American crocodile is confronted with threats from hunting for their hides as well as the conversion of their habitat into beachfront properties. This issue is particularly concerning in Florida where they are solely found within the United States. It is optimistic that through collaborative efforts by FPL and CITES, there will be a flourishing population of American crocodiles.
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