Due to their valuable hide, Morelet's crocodiles were hunted almost to extinction through the years 1940 to 1950. Under the Mexican Wildlife Protection Act, hunting them became illegal and their numbers have steadily risen, although illegal poaching and habitat loss continue to threaten the animal. To counteract this, Mexico has begun breeding Morelet's crocodiles in captivity. However, some individuals have escaped to form feral populations outside of their regular breeding zones, creating a problem for the populations of American crocodile, which must compete with this newly-invasive species.
Now primary focus remains in the development of sustainable use programs, such as commercial farming. More general knowledge about the species is required first, however. Status in the south of Belize is unknown; reports suggest the species is widely distributed in the Mexican states of Tabasco, Chiapas, Yucatan and Quintana Roo, and their situation in the interior of Guatemala is unknown. There remains little information on both specific numbers and general behavior patterns needed to judge their actual status throughout most of its range.
Morelet's crocodiles are listed as Endangered under the U.S. Endangered Species Act, and are included in Appendix I of the CITES Treaty. The IUCN rates the species as "Lower Risk", but this rating would revert to Threatened or Endangered if ongoing conservation efforts were ended.
US Federal List: threatened
CITES: appendix i
IUCN Red List of Threatened Species: lower risk - conservation dependent
While Morelet's crocodiles tend to be dominant predators in their communities, their eggs and young often fall prey to older juveniles, larger mammals, snakes, wading birds, and gulls. A key protection from predators is their tough hide and their loud vocal cries. Larger individuals are potentially preyed upon by humans and jaguars.
Known Predators:
The primary distinguishing feature of Crocodylus moreletii is the snout, which is uncharacteristically blunt for a crocodile. The snout has nostrils centered at its end. The eyes are situated behind the snout and ears behind the eyes. The location of all the sensory receptors are on the same plane (the top of the head) which allows them to be completely submerged in water and still have the ability to hear, see, and smell. Their eyes, which are silvery-brown, have special eyelids with nictitating membranes covering them, allowing for vision underwater. Morelet's crocodiles generally have 66 to 68 teeth, with the distinguishing purely Crocodylus characteristic of having them in perfect alignment. Their appearance and color is similar to the American crocodile, but Morelet's crocodiles tend to be a darker grayish-brown. Adults have dark bands and spots before the tail, while juveniles are a brighter yellow with black banding. Morelet's crocodiles lack bony plates (ventral osteoderums) beneath the skin. They have powerful legs with clawed webbed feet, and large tails that allow them to swim with powerful thrusts. They are medium-sized crocodiles, averaging 3 m and attaining a maximum of 4.7 m.
Range mass: 38.5 to 58.1 kg.
Average mass: 51 kg.
Range length: 2.2 to 4.7 m.
Average length: 3.0 m.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: male larger
Because they are both rare and difficult to study, not much is known about specific life cycles. Morelet's crocodiles that are bred in captivity appear to have a slightly longer lifespan (up to 80 years) than those that live in the wild (50 to 65 years). Females appear to live slightly longer than males.
Range lifespan
Status: captivity: 80 (high) years.
Typical lifespan
Status: wild: 50 to 65 years.
Average lifespan
Status: wild: 60 years.
Typical lifespan
Status: captivity: 55 to 70 years.
Average lifespan
Status: captivity: 65 years.
Morelet's crocodiles live primarily in freshwater areas such as swamps and marshes and can also be found in forested riparian habitats. Recently, C. moreletii has even been found residing in coastal brackish water. Juveniles prefer denser cover for protection, and adults tend to aestivate in burrows during the dry season.
Habitat Regions: temperate ; tropical ; terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water
Wetlands: marsh ; swamp
Other Habitat Features: riparian
Morelet's crocodiles are found on the eastern coastal plain of Mexico, across most of the Yucatan peninsula, and throughout Belize and northern Guatemala. Their range also overlaps that of the American crocodile, but the relationships between the two are unknown. Some Morelet's crocodiles have escaped from captive breeding areas in Mexico outside their normal range.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Morelet's crocodiles vary in diet according to their age and size. Juveniles eat small invertebrates and fish. Sub adults feed on aquatic snails, fish, small birds, and mammals. Adults feed on larger prey, including birds, fish, lizards, turtles, and domestic animals such as dogs. They can also become cannibalistic in times of low food, eating newborns. Crocodylus moreletii is generally shy around humans, but larger ones may attack if provoked.
Animal Foods: birds; mammals; amphibians; reptiles; fish; carrion ; insects; mollusks; aquatic crustaceans
Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore )
While not much information is known about the specific impact of the Morelet's crocodiles on their ecosystem, they do share many similar traits with the American crocodile, such as the role of primary carnivore in the ecosystem, thus affecting nutrient dispersal and ecosystem dynamics.
Unlike most other species of crocodilian, Morelet's crocodiles have no bony plates (called osteoderms) in their skin. This makes the skin more valuable as leather, and has motivated over-hunting.
Also, studies of the levels of mercury within the eggs of Morelet's crocodiles in Belize has also led to clues about biological contamination there.
Positive Impacts: body parts are source of valuable material; research and education
Although generally shy, as with any crocodile, C. moreletii has been known to bite humans if provoked.
Negative Impacts: injures humans (bites or stings)
When born, juveniles generally weigh about 31.9 grams. Morelet's crocodiles have three main life stages, classified through their length: juveniles < 100 cm, sub adults 100-150 cm, and adults >150 cm. Not much information is known about the specific life cycle of this crocodile. As in all crocodilians, however, sex is determined by the incubation temperature of the eggs.
Development - Life Cycle: temperature sex determination
Juveniles communicate through vocalization (known as barking) when born, though not much information is known about specific social communication. They tend to follow the basic patterns of all Crocodylus, which are the most vocal of all reptiles; their calls tend to differ depending on age, sex and situation. They may share the similar habit of the American crocodile, whose young are not as vocal as other species, which may be a response to high hunting pressures, resulting in a rapid adaptation for survival.
Scales covering most of the head and parts of the body are equipped with integumentary sense organs (ISO's) that perform a number of tasks, such as detecting pressure, salinity, and vibrations.
Communication Channels: visual ; tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Texas Tech currently maintains extensive research in Belize studying the genetics of different populations and the impact of various pesticides and heavy metal contamination throughout this species. Other research institutions include the Lamanai Research Center in Belize and researcher Howard Hunt of the Atlanta Zoo in Cox Lagoon, Belize.
Not much information is known about particular mating habits between males and females, although they appear to follow some of the same mating habits (such as being polygynous) of the American crocodile (Crocodylus acutus). Probably large males dominate the other males in their area, and females prefer to mate with the dominant males.
Mating System: polygynous
Oviposition for crocodiles living on the Yucatan primarily takes place in Chiapas between April and June. Crocodylus moreletii is unique because it is the only crocodile known to be exclusively mound nesting, laying between 20 and 40 eggs in nests that are approximately 3 m wide by 1 m high. Some nests have been found containing more than one female's eggs.
At hatching time, two to three months after laying the eggs, female Morelet's crocodiles have been known to carry eggs to water areas and crack them open. Reproductive rates are generally high among C. moreletii because of the relatively early maturation of the females. Not much information is available about the specific behavior of juveniles or the fertilization process. Research is currently being conducted in these areas.
Breeding interval: Morelet's crocodiles breed once a year directly before the rainy season.
Breeding season: Oviposition takes place between April and June. The incubation period lasts 2 to 3 months.
Range number of offspring: 20 to 40.
Range age at sexual or reproductive maturity (female): 7 to 8 years.
Average age at sexual or reproductive maturity (female): 7 years.
Range age at sexual or reproductive maturity (male): 7 to 8 years.
Average age at sexual or reproductive maturity (male): 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Female Morelet's crocodiles guard their nests until the eggs are ready to hatch. Studies among captive Crocodylus moreletii show females will respond to newborn vocalizations and open the nests. Males and females will also fiercely defend hatchlings against larger juveniles or other predators. Not much information is known about further interaction between juveniles and parents.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male, Female); pre-weaning/fledging (Protecting: Male, Female); pre-independence (Protecting: Male, Female)
This taxon is found in theMarismas Nacionales-San Blas mangroves ecoregion contains the most extensive block of mangrove ecosystem along the Pacific coastal zone of Mexico, comprising around 2000 square kilometres. Mangroves in Nayarit are among the most productive systems of northwest Mexico. These mangroves and their associated wetlands also serve as one of the most important winter habitat for birds in the Pacific coastal zone, by serving about eighty percent of the Pacific migratory shore bird populations.
Although the mangroves grow on flat terrain, the seven rivers that feed the mangroves descend from mountains, which belong to the physiographic province of the Sierra Madre Occidental. The climate varies from temperate-dry to sub-humid in the summer, when the region receives most of its rainfall (more than 1000 millimetres /year).
Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans), Buttonwood (Conocarpus erectus) and White Mangrove trees (Laguncularia racemosa) occur in this ecoregion. In the northern part of the ecoregion near Teacapán the Black Mangrove tree is dominant; however, in the southern part nearer Agua Brava, White Mangrove dominates. Herbaceous vegetation is rare, but other species that can be found in association with mangrove trees are: Ciruelillo (Phyllanthus elsiae), Guiana-chestnut (Pachira aquatica), and Pond Apple (Annona glabra).
There are are a number ofreptiles present, which including a important population of Morelet's Crocodile (Crocodylus moreletii) and American Crocodile (Crocodylus acutus) in the freshwater marshes associated with tropical Cohune Palm (Attalea cohune) forest. Also present in this ecoregion are reptiles such as the Green Iguana (Iguana iguana), Mexican Beaded Lizard (Heloderma horridum) and Yellow Bellied Slider (Trachemys scripta). Four species of endangered sea turtle use the coast of Nayarit for nesting sites including Leatherback Turtle (Dermochelys coriacea), Olive Ridley Turtle (Lepidochelys olivacea), Hawksbill Turtle (Eretmochelys imbricata) and Green Turtle (Chelonia mydas).
A number of mammals are found in the ecoregion, including the Puma (Puma concolor), Ocelot (Leopardus pardalis), Jaguar (Panthera onca), Southern Pygmy Mouse (Baiomys musculus), Saussure's Shrew (Sorex saussurei). In addition many bat taxa are found in the ecoregion, including fruit eating species such as the Pygmy Fruit-eating Bat (Artibeus phaeotis); Aztec Fruit-eating Bat (Artibeus aztecus) and Toltec Fruit-eating Bat (Artibeus toltecus); there are also bat representatives from the genus myotis, such as the Long-legged Myotis (Myotis volans) and the Cinnamon Myotis (M. fortidens).
There are more than 252 species of birds, 40 percent of which are migratory, including 12 migratory ducks and approximately 36 endemic birds, including the Bumblebee Hummingbird, (Atthis heloisa) and the Mexican Woodnymph (Thalurania ridgwayi). Bojórquez considers the mangroves of Nayarit and Sinaloa among the areas of highest concentration of migratory birds. This ecoregion also serves as wintering habitat and as refuge from surrounding habitats during harsh climatic conditions for many species, especially birds; this sheltering effect further elevates the conservation value of this habitat.
Some of the many representative avifauna are Black-bellied Whistling Duck (Dendrocygna autumnalis), Great Blue Heron (Ardea herodias), Roseate Spoonbill (Ajaia ajaja), Snowy Egret (Egretta thula), sanderling (Calidris alba), American Kestrel (Falco sparverius), Blue-winged Teal (Anas discors), Mexican Jacana (Jacana spinosa), Elegant Trogan (Trogan elegans), Summer Tanager (Piranga rubra), White-tailed Hawk (Buteo albicaudatus), Merlin (Falco columbarius), Plain-capped Starthroat (Heliomaster constantii), Painted Bunting (Passerina ciris) and Wood Stork (Mycteria americana).
Morelet's crocodile (Crocodylus moreletii), also known as the Mexican crocodile or Belize crocodile, is a modest-sized crocodilian found only in fresh waters of the Atlantic regions of Mexico, Belize and Guatemala.[2][5] It usually grows to about 3 metres (10 ft) in length. It is a Least Concern species. The species has a fossil record in Guatemala.[6]
Morelet's crocodile was first described in 1850 in Mexico by the French naturalist Pierre Marie Arthur Morelet. The species was subsequently named after him.[7][8] It was long confused with the American and Cuban crocodiles because of similar characteristics and an ambiguous type locality. It was not generally accepted as a separate species until the 1920s.
The genus Crocodylus likely originated in Africa and radiated outwards towards Southeast Asia and the Americas,[9] although an Australia/Asia origin has also been considered.[10] Phylogenetic evidence supports Crocodylus diverging from its closest recent relative, the extinct Voay of Madagascar, around 25 million years ago, near the Oligocene/Miocene boundary.[9]
Below is a cladogram based on a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data,[11] as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay.[9]
CrocodylinaeVoay†
CrocodylusCrocodylus Tirari Desert†
Asia+AustraliaCrocodylus johnstoni Freshwater crocodile 
Crocodylus novaeguineae New Guinea crocodile
Crocodylus mindorensis Philippine crocodile
Crocodylus porosus Saltwater crocodile 
Crocodylus siamensis Siamese crocodile 
Crocodylus palustris Mugger crocodile 
Crocodylus suchus West African crocodile
Crocodylus niloticus Nile crocodile 
Crocodylus moreletii Morelet's crocodile
Crocodylus rhombifer Cuban crocodile 
Crocodylus intermedius Orinoco crocodile
Crocodylus acutus American crocodile 
Morelet's crocodile has a very broad snout with 66 to 68 teeth when they are fully mature. They are dark grayish-brown in color with dark bands and spots on the body and the tail. This is similar to other crocodiles, like the American crocodile, but the Morelet is somewhat darker. Juvenile crocodiles are bright yellow with some dark bands. The crocodile's iris is silvery brown. They have four short legs, giving them a rather sprawling gait, and a long tail, which is used for swimming. The hind feet of the crocodiles are webbed. They have very explosive capabilities because of their strong muscles and are fast runners.[7]
Morelet's crocodile is small compared to most other crocodiles. The males can become larger than the females. The average adult Morelet's crocodile is about 2.1 m (6 ft 11 in), with a typical length range of 1.5 to 2.7 m (4 ft 11 in to 8 ft 10 in) (the lower measurement representing the mean total length of a female at sexual maturity which is attained at roughly 7–8 years of age in the wild).[12][13] Almost all crocodiles in excess of 2.5 m (8 ft 2 in) are males and at this advanced stage of maturity, the male goes through a significant change in skull osteological morphology as the skull appears to increase in broadness and robustness.[14] Large adult males can attain a length of 3 m (10 ft), anything in excess of this is considered exceptionally rare for this species however the species has a maximum reported length of 4.5 m (15 ft), with two other outsized specimens reportedly measuring 4.1 and 4.3 m (13 and 14 ft), respectively.[13][15][16] One mature adult specimen measuring 2.84 m (9 ft 4 in) and weighing 110 kg (240 lb) had a bite force of 4,399 N (989 lbf).[17] The weight of a large 3 m (10 ft) wild male crocodile is estimated to average around 150 kg (330+3⁄4 lb), although mass is likely much more in outsized individuals.[13][18] One large male with a presumed total length of around 3.5 m (11 ft 6 in) weighed about 250 kg (550 lb).[19] Another large individual measuring 3.3 m (10 ft 10 in) in length weighed 180 kg (400 lb).[20] Overall, this species is similar in appearance and morphology to the Cuban and the larger American crocodiles.
Morelet's crocodile can be found in freshwater habitats in Central America and along the Gulf of Mexico stretching through Belize, Guatemala, and to Mexico.[21] The Belizean pine forests are an example of the type of ecoregion in which they occur.[22]
In their freshwater habitats, they prefer isolated areas that are secluded. This species of crocodile can mainly be found in freshwater swamps and marshes which are located inland, and in large rivers and lakes.[23] Both of these habitats are forested to help add cover.[7]
The Morelet can also be found along the coast in brackish waters[2] and the grassy savannas on the Yucatán Peninsula.[24] These crocodiles become much more distributed during the rainy seasons when flooding occurs and it is easier for them to move elsewhere.[24]
Juvenile crocodiles live in very dense cover to protect them from other predators that might be in the area and will remain there until they become older and able to fend for themselves. Adult crocodiles are known to dig out burrows during dry seasons in their area.[7] The range of this crocodile can overlap with the American crocodile, which can sometimes lead to them being confused with one another.
Recently, the Morelet's crocodile has been introduced into the Rio Grande (Rio Bravo in Mexico).[25] Several newspaper outlets on the Mexican side of the border report of reptiles inhabiting the river appearing not to be the American alligator which is native to Texas, but the Morelet's crocodile which is native to Tamaulipas from San Fernando southward.[26][27] Crocodiles have been seen in the cities of Matamoros,[28][29][30] Reynosa[31][32][33][34][35][36] and as far north as Nuevo Laredo.[37][38] The sightings have prompted several municipal police departments to put up signs warning people about entering the river.[39]
Like most crocodilians, Morelet's crocodiles are highly opportunistic and will prey on practically anything that they can overpower that comes in their territories.[40] Juvenile crocodiles feed largely on fish and insects until they become bigger and more capable of bringing down larger prey.[23] Adults largely prey on small mammals, birds, other reptiles and fish, as well as gastropods, crustaceans and other invertebrates.[16][40][41] These small mammals can include domesticated animals like cats and dogs. Large specimens have been shown to be able to overtake large prey. Dogs and goats have been taken by this species, including a record of a 2.9 m (9 ft 6 in) adult killing an English sheepdog which weighed at least 35 kg (77 lb).[42] Adults have also been recorded eating even larger animals, including adult and nearly-grown cattle and an adult tapir, although these have been cases of scavenging on caracasses, with the tapir having been killed by a jaguar (it is possible that the jaguar was present when the crocodile fed).[43] Crocodiles have been known to be cannibalistic towards smaller specimens. Although previously thought to be inoffensive, there have been recent reports that the species has attacked humans on multiple occasions and at least 12 documented human fatalities have occurred.[44] Despite the relatively small size of the species, large adult Morelet's are aggressive and easily capable of overpowering an unaware human near the water. Due to partial consumption, recorded fatal attacks are likely predatory rather than defensive in nature.[45][46][47]
Breeding usually takes place between April and June[24] and the eggs are laid before the start of the rainy season. Morelet's crocodiles are unique among North American crocodiles in that they build mound nests only, and not mound and hole nests. These mound nests are about 3 m (10 ft) wide and 1 m (3 ft 3 in) high and can be found near the water or on floating vegetation. A female crocodile can lay between 20 and 45 eggs and nests have been found containing eggs from more than one female. The eggs are buried and the nests are guarded by females. The eggs usually hatch after 80 days of incubation[24] and hatchlings are normally about 17 cm (6+1⁄2 in) long.[5] After the eggs have hatched the female crocodile will carry her young to the water where they are protected by both parents and will later leave them to fend for themselves. Females are highly protective of their young and have reportedly been observed to aggressively displace intruders and humans if distress calls of the baby crocodiles are heard and even father crocodiles have been observed to spring to the defense of young crocodiles.[48][49] In captivity, juvenile crocodiles are treated aggressively by adult crocodiles but never hatchlings.[50]
Morelet's crocodile has long been threatened by habitat destruction and illegal hunting.[51] Both of these factors have significantly lowered their populations. It was hunted for its hide during the 1940s and 1950s[51] because high-quality leather can be made from their skins.[52][53]
Morelet's crocodile (Crocodylus moreletii), also known as the Mexican crocodile or Belize crocodile, is a modest-sized crocodilian found only in fresh waters of the Atlantic regions of Mexico, Belize and Guatemala. It usually grows to about 3 metres (10 ft) in length. It is a Least Concern species. The species has a fossil record in Guatemala.
