Spectacled caiman
The spectacled caiman, also known as the white caiman, common caiman, and speckled caiman, is a crocodilian in the family Alligatoridae. It is brownish-, greenish-, or yellowish-gray colored and has a spectacle-like ridge between its eyes, which is where its common name come from. It grows to a length of and a weight of, with males being both longer and heavier than females. Its diet varies seasonally, commonly consisting of crabs, fish, small mammals, amphibians and snails. Breeding occurs from May to August and 14–40 eggs are laid in July and August. This crocodilian has a large range and population; it is native to much of Latin America, and has been introduced to the United States, Cuba, and Puerto Rico.
Taxonomy
The spectacled caiman was described by Carl Linnaeus in 1758, originally as Lacerta crocodilus. It has since been redescribed several times, including as Caiman sclerops by Schneider in 1801. Although Caiman crocodilus is now the scientific name of the species, some scientists still prefer using sclerops, as having crocodilus as the scientific name for a caiman may cause confusion.Classification
The spectacled caiman is one of three extant species of the genus Caiman, the other two being the Yacare caiman and the Broad-snouted caiman. There are also several extinct fossil species in the genus Caiman, possibly up to eight species. The spectacled caiman is a member of the caiman subfamily Caimaninae, and is one of six living species of caiman. It is most closely related to the yacare caiman, as shown in the cladogram below, based on molecular DNA-based phylogenetic studies:Subspecies
The spectacled caiman has four recognized subspecies:- C. c. apaporiensis, commonly known as the Rio Apaporis caiman was once thought to be extinct but was rediscovered; is endemic to Colombia and possibly the Venezuelan Llanos.
- C. c. chiapasius ; distributed in Mexico, Central America, and northern South America.
- C. c. crocodilus, the nominate subspecies, commonly known as the spectacled caiman; found in various parts of South America, such as Venezuela, Trinidad, Tobago, Brazil, etc.
- C. c. fuscus, commonly known as the brown caiman; lives from Nicaragua to Colombia, Ecuador, and Venezuela.
The Rio Apaporis caiman was believed to have become extinct by 1981, when the last known specimen died in a zoo. However, a specimen was captured in an expedition by Colombian conservation biologist Sergio Balaguera-Reina in 2018. Later, the subspecies was discovered again by wildlife biologist Forrest Galante for the television show Extinct or Alive in 2019 and identified by DNA sampling. Galante has advocated for the Rio Apaporis caiman to be considered a distinct species, while Balaguera-Reina maintains its official status as a subspecies.
Distribution
The spectacled caiman has the largest range of any caiman, and of any New World crocodilian. It is found in various countries throughout the Americas. It lives in Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Peru, Suriname, Trinidad and Tobago, and Venezuela, and may also be extant in Belize and Bolivia. In Brazil, the species lives in the rivers Amazon, Araguaia, Araguari, Itapicuru, Rio Negro, Paranaíba, Solimões, Tapajós, Tocantins, and Xingu.As an introduced species
It has been introduced to Isla de la Juventud in Cuba, Puerto Rico, and Florida in the United States. In Florida, it is sometimes misidentified as the American alligator. Invasive populations have become established in South Florida, with isolated records further north in the state. Genetic study indicates two separate introduction events into Florida.Habitat
It is intolerant to cold climates, so its range is unlikely to expand to further north than Florida. It usually lives in forests, inland bodies of fresh water, grasslands, shrublands, and savannas, but is very adaptable. It prefers habitats with calm water containing floating vegetation, usually flooding and drying seasonally. It is most common in low-lying areas, but has been found at elevations of up to. It is able to live in human-inhabited areas.Description
The spectacled caiman is a small to medium-sized crocodilian. Females generally grow to no more than , but can rarely grow to nearly. Adult males can regularly reach while large mature ones grow to, although relatively few get to the upper size. The maximum reported size for the species is. The body mass of most adults is between, with males typically being considerably heavier than females. Some males in the Llanos have been reported to grow to up to.The upperside of the species is mostly brownish-, greenish-, or yellowish-gray colored and has dark brown crossbands, with a lighter underside. It has a greenish iris. and wrinkled eyelids. It changes color seasonally – during colder weather, the black pigment within its skin cells expands, making it appear darker.
The species has an enlarged 4th tooth, and the teeth in its lower jaw penetrate into a socket in its upper jaw. It has a long snout that tapers moderately, with an unexpanded tip. Several ridges begin in front of its eyes and travel to the tip of its snout. Its common name comes from a bony ridge between its eyes, which gives the appearance of a pair of spectacles.
Biology and behavior
The spectacled caiman can move rapidly when threatened, but is usually immobile, resting on shores or partly in water. In the rainy season, males become aggressive and territorial. Spectacled caiman have Müller glial cells in their eyes that contribute to excellent night vision.Hunting and diet
Usually hunting at night, the diet of the spectacled caiman varies seasonally. During the wet season, it primarily eats snails and freshwater crabs, while it mostly eats fish in the dry season. Smaller specimens tend to eat more insects and freshwater shrimp, while larger ones more frequently consume mammals and fish. Overall, the most common animals in this species' diet are crabs, other crustaceans, fish, mammals, snails and other molluscs. Other animals that have been known to be a part of its diet include amphibians, arachnids, birds, myriapods, reptiles, and small mammals. Older animals are capable of taking larger, mammalian prey. As conditions become drier, caimans can stop feeding, although cannibalism has been reported under such conditions as well. It has also been known to eat plant matter; in a study of this species in Puerto Rico, about 55% of adult specimens had plants in their diet, primarily grass and seeds. About 8% of adults and 6% of juveniles in the study had gastroliths in their stomach as well. Although the species has been suggested to control piranha populations, piranhas have not been found to be a normal diet component, unlike the yacare caiman. According to the Crocodilian Species List, it is probably a generalist species, being able to adapt to a variety of prey.Communication
The spectacled caiman uses nine different vocalizations and 13 visual displays to communicate with individuals of its species. Both adults and young produce calls for group cohesion. Males are known to communicate by moving their tail to a certain position, such as making it vertical or arched. Juveniles vocalize when in distress and adult females emit calls to warn young of threats.Reproduction
The spectacled caiman reaches sexual maturity from four to seven years old, at a length of for females and for males. Usually, the more dominant individuals mature more quickly. There is no strict reproductive hierarchy in spectacled caiman, but studies show larger males have more success breeding. Specimens choose mates and engage in copulation from May to August, the wet season. The females build nests as a mound of dense vegetation, in areas that are close to water but not at risk of being flooded. The nests are over in diameter and can be high, but the exact size depends on the resources available. Eggs are laid in July and August; the species very rarely nests in the winter, as the temperature is too low for the eggs. Clutch size is 22 on average, but can range from 14 to 40. Larger females have been known to lay larger eggs compared to smaller females. Females stay close to their nests during the incubation period, as several species, such as lizards in the genus Tupinambis, have been known to destroy nests and prey on the eggs. White-nosed coatis and foxes also raid nests. Flooding and human egg collecting can also be a threat to the nests. In a study in the Central Amazonia assessing reproductive similarities between C. crocodilus and Melanochus niger, research found that they indiscriminately separate their nests at larger distances than other species in this family, most likely to avoid predation.Temperature is important to the developing eggs, so females build their nests in a way that insulates them from extreme temperature changes. As the vegetation in the nests decays, the nests produce heat which can keep the eggs about 5 °C warmer than if they were insulated by mud alone. Heat not only incubates the eggs, but also determines the sex of the developing caimans. When the temperature inside the nest is about or higher, the caimans become female, and otherwise become male. Young hatch after 90 days, with 20–25 percent of eggs hatching successfully. They are yellow with black spots, a coloration which fades away as they grow older, with a length of. Parents raise their young in crèches, with one female taking care of her own, as well as several others' offspring. They take care of their young for 12–18 months. Young are threatened by various predators, such as raptors and wader birds, causing most to die in their first year. These juveniles are also preyed upon by large fish, large snakes, and other crocodilians.