Yacare Caiman

C. yacare is a medium-sized caiman, brown in color. Male specimens grow to 2–3 m (6 ft 7 in – 9 ft 10 in) in total length (including tail) and up to 58 kg (128 lb) in weight. Females are much smaller, with an adult total length of 1.4 m (4 ft 7 in) and weight of 14–23 kg (31–51 lb). The average snout–vent length (SVL) of hatchlings is 12.49 cm (4.92 in) for females and 12.84 cm (5.06 in) for males. Based on a study of the growth of multiple specimens in the Pantanal from 1987 to 2013, both sexes are about 50 cm (20 in) SVL at age five. By age 15, they have mostly finished growth, with females being about 80 cm (31 in) SVL and males over 100 cm (39 in) SVL. The study also showed that individuals have significant variation in their growth rates.

Dark marks are distributed across the body; most noticeably, its lower jaw is covered with three to five blotches. It has a smooth snout, which is medium in length and broad. It has lumps on its eyelids and a curved ridge between its eyes. It has osteoderms on its scales, a feature also present in the spectacled caiman. It has an average of 74 teeth, with 5 pre-maxillary, 14–15 maxillary, and 17–21 mandibular. Some of the teeth on its lower jaw can poke through holes in its upper jaw. This feature makes its teeth more prominent and has been compared to piranhas, which has established the common name "piranha caiman".

The range of the yacare caiman includes Argentina (north), Bolivia, Brazil (south), and Paraguay. It is one of three species of genus Caiman in South America, the others being the broad-snouted caiman (C. latirostris) and the spectacled caiman (C. crocodilus), with more easterly and northerly ranges, respectively. The yacare caiman is one of the most common species of caiman on its continent.

The yacare caiman is ecologically similar to the spectacled caiman. It lives in semi-aquatic habitats, including lakes, rivers, and wetlands, but is able to adapt to a variety of habitats. Individuals sometimes move to different locations in groups if their habitat is disturbed. The species' diet consists of aquatic animals, such as snails and fish, and occasionally snakes. It has also been known to eat capybaras. When hunting for snails, this caiman looks within vegetation floating in water and uses its jaws to break the shells of the snails. In July 1986, the stomach of a specimen in Bolivia was observed to be full of mud, along with small parts of eggshells that likely belonged to a caiman. In general, crocodilians can eat the eggshells of their own young subsequent to the young hatching.

Its specific name, “yacare” (also written “jacare”) entered English primarily through Portuguese, which had adopted the indigenous Tupi-Guarani term jakare to refer to certain caimans and similar reptiles from South America. The adoption of this word into Portuguese (jacaré) and Spanish (yacaré) is due to contact between the Guarani people and the conquistadors during the colonial period and subsequent centuries of linguistic coexistence.