In the world there is a concentration of 24 species of crocodilians spread over about 90 countries, which are divided between the families of crocodiles, alligators and gharials, however, it is in the countries of South America where we can find the largest number of them. Brazil is considered one of the countries with the greatest diversity of crocodilians, in it we find six species of three distinct genera, they are: Caiman latirostris, Caiman crocodilus, Caiman yacare, Paleosuchus palpebrosus, Paleosuchus trigonatus and Melanosuchus niger that are part of the Alligatoridae family and the subfamily Caimaninae. However, all the species mentioned are alligators, since in Brazil there are no free-living crocodiles or gharials. (MEDEM, 1983; COSTA and BÉRNILS, 2018).
Alligators are top-of-the-chain animals, in this way, they feed on different species of animals, preferably on animals that appear to be weak or sick, as they do not need to spend a lot of energy in the attack. In addition, alligators are ectothermic, meaning their body temperature will vary depending on the environment in which they live. They have a dry skin that is quite resistant to water loss, covered with horny scales, without glands and have dermal plates under the dorsal scales, which run from the neck to the tail. Its snout is short and wide in a "U" shape, it has conical teeth and presents the cloaca, a cavity common to both the excretory and reproductive systems, in the terminal part of the digestive system. They are oviparous animals, their eyes are lateralized and they have an upper and lower eyelid, which is basically a transparent membrane called the nictitating membrane, they have pulmonary breathing, a heart divided into four chambers and a non-protactile tongue that is basically attached to the floor of the oral cavity. , which can isolate the nasopharynx. (AZEVEDO, 2003; BASSETTI, 2006).
The largest species of alligator is the Black Alligator (Melanosuchus niger) and can reach a size of over 6 meters. In Brazil, it is distributed in the North and Center-West regions, however, 70% of its population is located in the Amazon basin, in addition to being found in Colombia, Bolivia, Ecuador, Peru and the Guianas (MEDEM, 1981). Paleosuchus species will be the smallest, the Smooth-fronted Caiman (Paleosuchus trigonatus), will reach 2.3 meters in the Amazon (MEDEM, 1981) and the Cuvier's Dwarf Caiman (Paleosuchus palpebrosus), has the maximum size .reported of 2.1 meters in the Pantanal (CAMPOS et al., 2010). Regarding the species of Caiman, their sizes are intermediate, reaching about 3.5 meters Broad-snouted Caiman (Caiman latirostris, while the Yacaré Caiman (Caiman yacare) usually reaches 2 meters and the Common Caiman (Caiman crocodilus) is medium-sized and grows up to 2.5 meters. (TRUTH and PIÑA, 2006).
REFERENCES
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CAMPOS, Z.; MAGNUSSON, W. E. Density and Biomass Estimates by Removal for an Amazonian Crocodilian, Paleosuchus palpebrosus. PLoS One, v. 5, n. 11, p. 1-7, 2016.
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MEDEM, F. Osteología craneal, distribución geográfica y ecología de Melanosuchus niger (Spix), Crocodylia: Alligatoridae. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, v. 12, p. 5-19, 1963.
MEDEM, F. Los Crocodylia de Sur América: Los Crocodylia de Colombia. Editorial Carrera: Bogotá, v. 1, 1981. 354 p.
MEDEM, F. Los Crocodylia de Sur América: Venezuela - Trinidad Tobago - Guyana - Suriname - Guayana Francesa - Ecuador - Perú - Bolivia - Brasil - Paraguay - Argentina - Uruguay. Editorial Carrera: Bogotá, v. 2, 1983. 270 p.
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VERDADE, L. M.; LARRIERA, A.; PIÑA, C. I. Broad-snouted caiman Caiman latirostris. In: MANOLIS, S.C.; STEVENSON, C. (Eds.). Crocodiles. Status Survey and Conservation Action Plan. 3ed.Gland, Switzerland: IUCN Publications Services Unit, 2010. p. 18-22.
VERDADE, L. M.; PIÑA, C. I. Caiman latirostris. Catalogue of American Amphibians and Reptiles (CAAR), 2006.