Choloepus didactylus

Linnaeus's two-toed sloth (Choloepus didactylus), also known as the southern two-toed sloth, unau, or Linne's two-toed sloth is a species of sloth from South America, found in Venezuela, the Guyanas, Colombia, Ecuador, Peru, and Brazil north of the Amazon River. There is now evidence suggesting the species' range expands into Bolivia. Sloths belong to the order Pilosa, which also includes anteaters. They belong to the super order Xenarthra, which includes the Cingulata. Xenarthra are edentate or toothless. They lack incisors and have a large reduction in number of teeth with only four to five sets remaining including canines. Modern sloths are divided into two families based on the number of toes on their front feet, Megalonychidae and Bradypodidae. Linnaeus's two-toed sloth and Hoffmann's two-toed sloth (Choloepus hoffmanni) belong to the family Megalonychidae, which included extinct ground sloths. Chloepus didactylus are larger than three-toed sloths. They have longer hair, bigger eyes, and their back and front legs are more equal in length. Their ears, hind feet and head are generally larger than Bradypodidae. They do however have a shorter tail. Their shoulder height, the height from the shoulder blade to the tips of the claw is longer than three-toed sloths, indicating longer arms. The species has relatively few teeth; it has four to five sets including canines and lacks incisors. The teeth lack enamel, consisting only of two layers ever-growing dentin. Supernumerary teeth have occasionally been observed, but this has been reported in almost all mammalian orders. This species of sloth is also known for its unique behavioural adaptions when confronted with a predator. Whilst on the ground, and vulnerable, if the Linnaeus's sloth encounters such a predator, they will rear up on their hind legs and 'run' backwards, away from the predator. This defensive behaviour, however, often results in injuries for the sloth as they cannot see where they are running, and will 'crash' into trees and other obstructions. Linne's two-toed sloth has a ten-month gestation period. Their inter-birth rate extends past sixteen months so there is not an overlap of young to care for. There is only one offspring per litter and the young becomes independent at about a year old. It takes longer for two-toed sloths to become independent. The gestation period is also longer than in three-toed sloths. It has been suggested that this difference may be caused by their difference in diet. C. didactylus is a solitary, nocturnal and arboreal animal, found in rainforests. The two-toed sloth falls prey to wild cats such as the ocelot and jaguar as well as large birds of prey such as the harpy and crested eagles. Predation mainly occurs when the sloth descends to the ground in order to defecate or change trees. Anacondas have also been known to hunt sloths. It is able to swim, making it possible to cross rivers and creeks, but maybe also making it more available to a predator like an anaconda.