Image Source: Corbis.com
American Crocodile
Crocodylus acutus
Taxonomic History
Modern Day Dino?
Photo by Frank Lane Picture Agency @ Corbis.com
Crocodilians are more closely related to
dinosaurs than any other non-avian animals
|
Crocodylus acutus (Cuvier 1807), Museum National d'Histoire Naturelle, Paris, France 10:55.
ORIGINAL NAME: Crocodylus acutus.
TYPES: 5 or more syntypes: MNHN, Paris.
TYPE LOCALITY: "La grande ile de Saint-Dominique, Antilles, Amerique" (=Hispanola; most probably the French portion which today is Haiti); restricted to "Santo Domingo, Puerto Plata," by Smith and Taylor 1950, Univ. Kansas Sci. Bull. 33(8):364; and further restricted to "L'Etang, Saumatre, Haiti," by Schmidt 1953, Check List N. Am. Amph. Rept., ed. 6:111.
DISTRIBUTION: South Florida, USA; Cuba and Isla de Juventud (=Isla de Pinos), Jamaica, and Hispaniola (known from fossils in Bahamas); in Atlantic coast drainages from Yucatan, Mexico, through Central America to near the mouth of the Orinoco River, Venezuela, and in the Pacific drainages from northern Sinaloa (known from fossils in Baja California), Mexico, south to the Tumbes River, in extreme northwestern Peru.
COMMENT: In revising earlier works on crocodiles, Cuvier 1807, MNHN 10:8-66, showed that plate 106, fig. 1, of Seba 1734, Loc. Rerum Nat. Thes. Acc. Descr. Vol 1, was too inaccurate to be indentified. Because its description was based soley on Seba's plate 106, fig. 1, Stejneger 1933, Copeia (3):118, stated that Crocodylus americanus Laurenti 1768, Spec. Synops. Rept. :54, was unavailable. Stejneger and Barbour 1917, Check List N. Am. Amph. Rept. :41; Stejneger 1917, Proc. U.S. Natl. Mus. 53:259-291; Mook and Mook 1940, Am. Mus. Novit. 1098:4-5; and most later authors used acutus Cuvier 1807 in combination with Laurenti's spelling of Crocodylus. Smith and Smith 1977, Synops. Herpetofauna Mexico 5:87-94, reviewed nomenclature and fixed Crocodylus americanus Laurenti 1768, as a junior synonym of Lacerta crocodylus Linnaeus 1758.
CONTRIBUTOR: W. King.
REVIEWER: P. Brazaitis, K. Dodd, M. Hoogmoed, F. Ross.
COMMON NAME: American crocodile, Caiman, Caiman de la Costa, Central American alligator, Cocodrilo, Lagarto.
Materials in this section derived from source 4
Return To Top Of Page
Species Description
Crocodile Tooth Structure
Photo by Danny Lehman @ Corbis.com
Note pronounced fourth lower tooth, which
distinguishes crocodiles from alligators
|
C. acutus is a large species, reported to have reached lengths of over 6 m (Perez-Higareda et al., 1990) in South America. The largest reported size in Florida is 4.6 m. Juveniles are light grey or yellowish with dark crossbands, which fade with age. Adults are typically tan to olive-brown or gray-brown dorsally, with or without dark markings. The venter is a pale white or yellow, and the area around the jaws is a dull yellow. Male American crocodiles attain greater lengths than females and possess an overall more massive musculature. Females are stouter in appearance, with a proportionally shorter tail and a less enlongate snout.
The American crocodile is the only true crocodile found in the United States. It's only U.S. relatives are the American alligator, which exists in abundance from Texas to N. Carolina, and the Spectacled caiman, which is an introduced species with an extremely limited range in S. Florida. The American crocodile and the American alligator are easily distinguishable (as are all crocodile and alligator species). Crocodiles in general have much narrower heads than alligators, and they are further characterized by a pronounced fourth lower tooth, which is visible when the mouth is shut. The fourth lower tooth of alligators and caimans fits into a pocket of the upper jaw.
Comparative Head Structure
Photo by Perry Conway @ Corbis.com
From left: crocodile, caiman, alligator
|
In Mexico, Belize, and Guatemala, the American crocodile shares much of its range with Morelet's crocodile (C. moreletii), which is much more similar to C. acutus than alligators or caimans. But these two species can be distinguished by a few key characteristics. The snout of C. acutus is relatively narrower and more enlongate than that of C. moreletii. The American crocodile possess a slight pre-orbital "hump", which is laterally visible between the eye and nasal; most other crocodilian species, including C. moreletii, lack this feature. Furthermore, the ventral scale pattern at the base of the tail is uniform in C. acutus but contains extra scale rows in other species.
Temperamentally, C. acutus rates somewhere in the middle of all Crocodilian species. Crocodiles are, as a general rule, more aggressive than alligators, and occasional human fatalities have been attributed to this species. However, it is not considered to be a true man-eater like its relatives of similar size, the Nile crocodile (Crocodylus niloticus) of Africa and the Saltwater crocodile (Crocodylus porosus) of Southeast Asia and Australia.
Materials in this section derived from sources 1, 2, 3, 5, and 6
Return To Top Of Page
Biogeography
The American Crocodile occurs in 17 countries: Belize, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, El Salvador, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Peru, Panama, United States, and Venezuela.
C. acutus occupies a small area in extreme S. Florida and the Keys, with most individuals occurring in an area of costal mangroves approximately 22 miles long by 12 miles wide, extending from lower Biscayne Bay south and east around the tip of the peninsula to central Florida Bay. It has been speculated that Florida's historic population of C. acutus was between 1,000 and 2,000 individuals. A study in 1973 estimated the population to be 500 or less. Half of these individuals, and 80% of the active nesting sites, are believed to be located within the Everglades National Park. More recent studies indicate that the population of nesting females has been stable or increasing over the last 20 years.
Range Map
image source: Crocodilian Species List
Materials in this section derived from sources 1, 7, and 8
Return To Top Of Page
Reproductive Behavior
Maternal Care
Photo by Jonathan Blair @ Corbis.com
All crocodilian species demonstrate maternal care,
especially in aiding hatchlings from the nest to water
|
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. In February or March gravid females will begin to create nests of sand, mud, and dead vegetation along the water's edge. It is crucial that the nest be constructed in the right location and with the correct amount of vegetation so that 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 certainly harm the health of the species 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 mother may cover the eggs with debris or leave them uncovered. The white, enlongate eggs are about 8 cm long and 5 cm wide and have a number of pores in the brittle shell. During the 75 to 80 day incubation period the parents of the eggs 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 racoons, foxes, skunks or other scavanging mammals.
Crocodilian Eggs
Photo by Jonathan Blair @ Corbis.com
Crocodilian eggs are somewhat brittle but softer than
bird eggs. Young of this species hatch after 75-80 days.
|
C. acutus exists mostly in tropical areas with distinct rainy seasons, and the young hatch out near the time of the first rains of the summer (July-August), after the preceeding dry season and before the bodies of water in which they live overflow their banks in flooding. It is at this stage in the development of their young when mother crocodiles exhibit a unique mode of parental care. During the hatching process, when the young crocodiles are most vulnerable to predation, they will instinctually 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 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. It is not until about five weeks after hatching that the young crocodiles disband in search of their own independent lives. Most of them, of course, will not survive, being preyed upon by various birds and larger fishes. But those that do survive the early stages of life will grow rapidly, feeding on insects, fish and frogs. Additionally, it has been reported that some young crocodiles will feed on each other.
Materials in this section derived from sources 1, 2, 5, and 6
Return To Top Of Page
Diet and Feeding Mechanism
Because C. acutus is long-snouted, even for a crocodile, it is presumed to feed primarily on fish; the long rows of teeth allow for easier capture of fish than, say, the shorter tooth rows of an alligator. American crocodiles in Florida are known to prey on bass, tarpon, and especially mullet. But this is not to say that this species preys entirely on fish. Crocodiles are largely opportunistic feeders (as are many reptiles), and therefore it is not uncommon to find them lying in wait for mammals that come to the water's edge or for water birds that frequent their habitat. Juveniles take a similar approach to feeding but on a smaller scale. They will eat nearly anything that is small enough for them to ingest, including insects, small fish, and frogs and their larvae. It has been reported that this species prefers to hunt during the first hours following nightfall, especially on moonless nights. It is, however, safe to assume that this crocodile will take a meal any time it can get one.
The feeding mechanism of crocodiles for large prey is unique in the animal kingdom (the mechanism for small prey, such as fish, is simply to ingest the food item whole). Once a crocodile succeeds in capturing a land mammal from the shore, it will proceed to drag it into the water and drown it. When the animal is dead the crocodile will hold on to one body part and roll its body until the affected part is completely twisted off, thereby creating a bite-size chunk that is easily ingested. If the prey is too large to be consumed in one sitting, it is not uncommon for the crocodile to take it to a hiding place, usually underneath an overhanging bank or submerged log, and consume it at a later time.
Adult Diet
Photo by Jonathan Blair @ Corbis.com
Adult American Crocodiles feed primarily on
fish, turtles, mammals, and water birds
|
Juvenile Diet
Photo by Jonathan Blair @ Corbis.com
Juveniles feed mostly on
insects, frogs, and small fish
|
Materials in this section derived from sources 2 and 3
Return To Top Of Page
Lifestyle
Caution!
Photo by Buddy Mays @ Corbis.com
Although attacks on humans are rare, C. acutus
is a large species that commands a wide berth
|
Like most reptiles, crocodiles spend the large part of their lives in inactivity. For the crocodile, this inactivity may be spent in one of three ways: basking on the bank, resting in a burrow, or waiting for prey. Within its range, C. acutus can often be found basking on sandbars or on the shores of the bodies of water in which is lives. This basking activity is important for raising the animal's body temperature to a level necessary for activity as well as for digesting food. American crocodiles are most often seen basking during the warmest times of the day, from late morning to early afternoon.
The American crocodile is reported to create burrows for hiding, resting, and to escape cold weather in the northernmost reaches of its range. The entrances to these burrows may be completely or partially submerged, and they extend into the banks from ten to thirty feet. At the furthest end, the burrow is widened out so its owner can turn around in it. Most of the time the burrow is only two feet below the surface of the bank.
The remainder of a crocodile's inactive time is spent waiting for prey. When stalking land prey, crocodiles are known to float just beneath the surface of the water with only their eyes and nostrils exposed. When a prospective meal is spotted, the crocodile will slowly move closer while maintaining its submerged position. Basking crocodiles that notice animals coming to a nearby shore for a drink will quickly and silently enter the water and assume this ambush position. Once the reptile makes its attack, the struggle and ingestion take a relatively short amount of time, and soon it will be back on the bank warming its body so it can digest its recent meal.
Close Encounters
Photo by Nik Wheeler @ Corbis.com
These Nile Crocodiles seem to be enjoying this golf
course in South Africa as much as the nearby golfers
|
C. acutus is an estuarine species that prefers to live in the brackish waters of mangrove swamps and the mouths of rivers. However, it has occasionally been found swimming at sea considerable distances from shore. This species has also been known to inhabit inland lakes. There has even been an authenticated report of a crocodile, presumed to be C. acutus, attacking a human who was snorkeling near the shore of Lago de Yojoa in Honduras. Fortunately, this attack did not result in a fatality.
Whether salty or fresh, water is a crucial component of life for crocodiles, and they are rarely found far from it. Almost all ambushes are launched in or from a body of water, but this is not always the case. There are at least two reports of the Nile crocodile coming completely out of the water in the daytime to capture its prey. In one of these instances, the crocodile didn't even take its victim back to the water but rather brought it to a nearby thicket and devoured it there. If anything, these instances should demonstrate the fact that crocodiles will capture prey at any time and in any place.
Another intersting aspect of this species' aquatic lifestyle is that it has been reported to be cleaned by certain kinds of fish in much the same way that remoras clean sharks. It has also been reported that the Saltwater crocodile has been observed opening its mouth on shore and allowing small shore birds to enter the mouth and scavange whatever food particles or invertibrates may be there.
Materials in this section derived from sources 2, 3 and 6
Return To Top Of Page
Conservation Information
Will He Survive?
Photo by W. Perry Conway @ Corbis.com
American Crocodile populations are
depleted in all of its 17 native countries
|
The American crocodile is an endangered species, listed by CITES in Appendix 1 and classified by the IUCN Red List 1990 as "Endangered." Thorbjarnarson (1992) reports that there is "poor" availability of survey data but a "high" need for wild population recovery. Of the 17 countries in which the American crocodile has traditionally been found, it has been depleted in 12, severely depleted in five, and totally wiped out in one. The principal threats to C. acutus are illegal hunting, habitat destruction, and introduced exotic animals.
A major reason that this species is in its current situation is because it produces a comercially valuable hide, and much of its past population decline can be attributed to a period of severe commercial overexploitation that occurred from the 1930s into the 1960s. In order to alleviate this dilemma, farming and ranching projects have been initiated in six countries. These endeavors allow for the legal production of crocodile products and thereby offer the promise of reducing the demand for the hides of wild animals. However, there is still need for close regulation so that the collection of adult breeders to stock these facilities does not further deplete the remaining wild populations.
Nearly half of C. acutus' 17 native countries have management programs based on complete protection, but only a few have enforced legislation. Two countries (El Salvador and Haiti) have no management programs whatsoever. If this species is to survive it is crucial that more complete data be collected. The farming and ranching programs stand to improve the situation, but only if such sustainable utilization is approached on a country-by-country basis and directly linked to the health of wild populations.
Materials in this section derived from source 8
Return To Top Of Page
Bibliography
1. Behler, John (1979): The Audubon Society Field Guide to North American Reptiles & Amphibians. Pp. 429-431. Knopf, Inc., New York.
2. Campbell, Jonathan (1998): Amphibians and Reptiles of Northern Guatemala, the Yucatan, and Belize. Pp. 284-286. University of Oklahoma Press, USA.
3. Guggisberg, C. A. W. (1972): Crocodiles: Their Natural History, Folklore, and Conservation. Pp. 79, 86, 94, 107, 138-150. Stackpole Books, Harrisburg, PA.
4. King, F. Wayne & Russell L. Burke (1989): Crocodilian, Tuatara, and Turtle Species of the World. Pp. 8-9. Association of Systematics Collections, Washington D.C.
5. Pope, Clifford (1955): The Reptile World: A Natural History of the Snakes, Lizards, Turtles, and Crocodilians. Pp. 12-13, 40-42. Knopf, Inc., USA.
6. Stafford, Peter & John Meyer (2000): A Guide to the Reptiles of Belize. Pp. 50-53. Academic Press, San Diego.
7. Supplementary Paper No. 41 (1973): "Crocodiles". P. 22. International Union for Conservation of Nature, Morges, Switzerland.
8. Thorbjarnarson, John (1992): Crocodiles: An Action Plan for their Conservation. Pp. 75-77, 91-93. International Union for Conservation of Nature, Gland, Switzerland.
Return To Top Of Page
Useful Links
Florida Museum of Natural History: Herpetology
Nonindigenous Aquatic Species
Online Species Summary
American crocodile skull for sale
2000 IUCN Red List of Threatened Species
Return To Top Of Page
List of Museums with Specimens
Department of
Herpetology
California Academy of Sciences
Golden Gate Park, San Francisco
CA 94118-4599
Section
of Amphibians and Reptiles
Carnegie Museum of Natural History
4400 Forbes Avenue
Pittsburgh, PA 15213
Division of Herpetology
Museum of Natural History
University of Kansas
Lawrence, KS 66045-2454
Department
of Herpetology
Natural History Museum of Los Angeles County
900 Exposition Blvd.
Los Angeles, CA 90007
Vertebrate Zoology
Division
Peabody Museum of Natural History
Yale University
P. O. Box 208118
New Haven, CT 06520-8118
Information and format of this section derived from:
The Combined Index to Herpetology Collections
Return To Top Of Page
NOTE: Not all pictures on this site are of C. acutus. A number of them are of C. niloticus. To note the distinguishing pre-orbital ridge in C. acutus, observe the picture under the heading "Modern Day Dino?," which is of an American crocodile. This can be contrasted with the image at the top of the page, which I am fairly sure is of a Nile crocodile (the image source is unclear about what species it is, but it clearly lacks the pre-orbital ridge).
**Picture of baby crocodile with frog in mouth used as link to top of page is by Jonathan Blair @ Corbis.com
Website by Taylor Larson
