Үш саусақты жалқаулар: Өмір салты мен ерекшеліктері

Genus of mammals

The three toed or three fingered sloths are arboreal neotropical mammals. |}

A study of mitochondrial cytochrome b and 16S rRNA sequences suggests that B. torquatus diverged from B. variegatus and B. tridactylus about 12 million years ago, while the latter two split 5 to 6 million years ago. The diversification of B. variegatus lineages was estimated to have started 4 to 5 million years ago.

Famously slow moving, a sloth travels at an average speed of Three toed sloths are about the size of a small dog or a large cat, with the head and body having a combined length of around and a weight of Unlike the two toed sloths, they also have short tails of , and they have three clawed toes on each limb. All sloths have three digits on their hindlimbs; the difference is found in the number of digits on the forelimbs; thus they are sometimes referred to as three fingered sloths. However, sloths are generally regarded as quadrupeds.

Like the two toed sloth, three toed sloths are agile swimmers. They are still slow in trees. The muscles that sloths use to grip and produce a pulling motion are much more prominent than those that produce a pushing motion. This means that they struggle to support their body weight when walking on all four limbs, so traveling on the ground is a dangerous and laborious process. Three toed sloths are arboreal (tree dwelling), with a body adapted to hang by their limbs. Large, curved claws and muscles specifically adapted for strength and stamina help sloths to keep a strong grip on tree branches. The abdominal organs close to their diaphragm (such as their stomach, liver, and kidneys) are attached to their lower ribs (or pelvic girdle in the latter case) by fibrinous adhesions, which prevent the weight of these organs from compressing their lungs when hanging, making inhalation easier. They live high in the canopy but descend once a week to defecate on the forest floor. During this week long interval, their feces and urine accumulate to about a third of their total body mass. Although they get most of their fluids from the leaves that they eat, they have been observed drinking directly from rivers. Because of their slow metabolism, they do not need to ingest many leaves on a daily basis, but when ambient temperatures are high, the symbiotic microbes and bacteria present in their gut will break down and ferment food at a faster rate. Conversely, when temperatures are lower, sloths will consume less, which is opposite to what has been observed in most other mammals. Their long, coarse fur often appears greenish, due not to pigment, but to algae growing on it. Sloths' greenish color and their sluggish habits provide an effective camouflage; hanging quietly, sloths resemble a bundle of leaves. They move between different trees up to four times a day, although they prefer to keep to a particular type of tree, which varies between individuals, perhaps as a means of allowing multiple sloths to occupy overlapping home ranges without competing with each other. Three toed sloths are predominantly diurnal, although they can be active at any hour of the day, while two toed sloths are nocturnal.

Members of this genus tend to live around 25 to 30 years, reaching sexual maturity at three to five years of age. Three toed sloths do not have a mating season but breed year round. Male three toed sloths are attracted to females in estrus by their screams echoing throughout the canopy. Sloth copulation lasts an average of 25 minutes. Male three toed sloths are strongly polygamous and exclude competitors from their territory. Males are also able to compete with one another within small habitable territories. Females give birth to a single young after a gestation period of around six months. The offspring cling to their mother's bellies for around nine months. They are weaned around nine months of age when the mother leaves her home territory to her offspring and moves elsewhere. Adults are solitary, and mark their territories using anal scent glands and dung middens. For the first few months after giving birth, mothers remain at just one or two trees and guide their young. At about five to seven months of age, when the young have become more independent, mothers expand their resources and leave their young in new areas. During natal dispersion, three toed sloths prefer tropical forests, often using riparian forest habitat to disperse while avoiding pastures and shade grown cacao. The home range for mothers is larger than those of young. After separation, only the mothers use the cacao growing forest, but both use riparian forests. Different types of trees are used by both mother and young, which indicates that this agricultural matrix provides an important habitat type for these animals.

Three toed sloths have no incisor or canine teeth, just a set of peg shaped cheek teeth that are not clearly divided into premolars and molars, and lack homology with those teeth in other mammals, and thus are referred to as molariforms. The molariform dentition in three toed sloths is simple and can be characterized as dental formula of:
Three toed sloths are unusual amongst mammals in possessing as many as nine cervical vertebrae, which may be due to mutations in the homeotic genes. All other mammals have seven cervical vertebrae, other than the two toed sloth and the manatee, which have only six.

Three toed sloths use their gut microbiome to break down the lignocellulose found in the leaves of the cecropia trees that they eat into short chain organic acids, which are then absorbed into the bloodstream to provide energy to the sloth. Firmicutes and Proteobacteria are the main bacterial phyla that dominate the sloth gut microbiome, which is less diverse than in many other herbivores. Not only are Firmicutes bacteria found in feces and digesta, but they are also found externally on the fur of sloths. Some research has found that Firmicutes bacteria in the genera Brevibacterium and Rothia can secrete antibiotic compounds that may provide protection from pathogenic bacteria.