Sloth

Sloths are among the animals that appear in the Jungle Bunch Universe.

## Description

Sloths are arboreal mammals noted for slowness of movement and for spending most of their lives hanging upside down in the trees of the tropical rainforests of South America and Central America. The six species are in two families: two-toed sloths and three-toed sloths. In spite of this traditional naming, all sloths actually have three toes. The two-toed sloths have two digits, or fingers, on each forelimb.

The sloth is so named because of its very low metabolism and deliberate movements, sloth being related to the word slow. This is an evolutionary adaptation to their low-energy diet of leaves, and to avoid detection by predatory hawks and cats who hunt by sight. Sloths are almost helpless on the ground but are able to swim. The grooved hairs of the sloth's shaggy coat is a host to symbiotic green algae which helps the sloth camouflage itself in the trees and provides nutrients to the sloth. The algae, in turn, nourishes sloth moths, some species of which exist solely on sloths.

They are classified in the order Pilosa along with the anteaters. Extinct sloth species include many megafaunal ground sloths, some of which attained the size of elephants, as well as marine sloths.

## Social Characteristics

### Physiology

Sloths can be 60 to 80 cm (24 to 31 in) long and, depending on species, weigh from 3.6 to 7.7 kg (7.9 to 17.0 lb). Two-

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Feeding brown-throated three-toed sloth (Bradypus variegatus), Cahuita National Park, Costa Rica
toed sloths are slightly larger. Sloths have long limbs and rounded heads with tiny ears. Three-toed sloths also have stubby tails about 5 to 6 cm (2.0 to 2.4 in) long. While almost all mammals have seven cervical vertebrae, two-toed sloths have only six, while three-toed sloths have nine, allowing them to rotate their heads through 270 degrees.

Sloths have colour vision, but have poor visual acuity. They also have poor hearing. Thus, they rely on their sense of smell and touch to find food.

Sloths have very low metabolic rates (less than half of that expected for a mammal of their size), and low body temperatures when active 30 to 34 °C (86 to 93 °F), and still lower when resting. Sloths are heterothermic, meaning their body temperature may vary according to the environment, normally ranging from 25 to 35 °C (77 to 95 °F), but able to drop to as low as 20 °C (68 °F), inducing torpor.

The outer hairs of sloth fur grow in a direction opposite from that of other mammals. In most mammals, hairs grow toward the extremities, but because sloths spend so much time with their limbs above their bodies, their hairs grow away from the extremities to provide protection from the elements while they hang upside down. In most conditions, the fur hosts symbiotic algae, which provide camouflage from predatory jaguars, ocelots, and harpy eagles. Because of the algae, sloth fur is a small ecosystem of its own, hosting many species of commensal and parasitic arthropods. There are a large number of arthropods associated with sloths. These include biting and blood-sucking flies such as mosquitoes and sandflies, triatomine bugs, lice, ticks, and mites. Sloths have a highly specific community of commensal beetles, mites and moths. Species of sloths recorded to host arthropods include: the pale-throated sloth, the brown-throated sloth, and Linnaeus's two-toed sloth. Incidentally, it appears that sloths benefit from their relationship with moths because the moths are responsible for fertilizing algae on the sloth, which provides them with nutrients.

### Activity

Their limbs are adapted for hanging and grasping, not for supporting their weight. Muscles make up only 25 to 30 percent of their total body weight. Most other mammals have a muscle mass that makes up 40 to 45 percent of the total body weight. Their specialised hands and feet have long, curved claws to allow them to hang upside down from branches without effort, and are used to drag themselves along the ground, since they cannot walk. On three-toed sloths, the arms are 50 percent longer than the legs.

Sloths move only when necessary and even then very slowly. They usually move at an average speed of 4 metres (13 ft) per minute but can move at a marginally higher speed of 4.5 metres (15 ft), if they are in immediate danger from a predator. While they sometimes sit on top of branches, they usually eat, sleep, and even give birth hanging from branches. They sometimes remain hanging from branches even after death. On the ground, the maximum speed of sloths is 3 metres (9.8 ft) per minute. Sloths are surprisingly strong swimmers and can reach speeds of 13.5 metres (44 ft) per minute. They use their long arms to paddle through the water and can cross rivers and swim between islands. Sloths can reduce their already slow metabolism even further and slow their heart rate to less than a third of normal, allowing them to hold their breath underwater for up to 40 minutes.

Wild brown-throated three-toed sloths sleep on average 9.6 hours a day. Two-toed sloths are nocturnal. Three-toed sloths are mostly nocturnal but can be active in the day. They spend 90 percent of their time motionless.

### Diet

Baby sloths learn what to eat by licking the lips of their mother. All sloths eat the leaves of the cecropia.

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Hoffman's two-toed sloth(Choloepus hoffmanni) feeding in Manuel Antonio National Park in Costa Rica
Two-toed sloths have a diverse diet of insects, carrion, fruits, leaves and small lizards, ranging over up to 140 hectares. Three-toed sloths, on the other hand, have a limited diet of leaves from only a few trees, and no mammal digests as slowly.

They have made adaptations to arboreal browsing. Leaves, their main food source, provide very little energy or nutrients and do not digest easily, so sloths have large, slow-acting stomachs with multiple compartments in which symbiotic bacteria break down the tough leaves. As much as two-thirds of a well-fed sloth's body weight consists of the contents of its stomach, and the digestive process can take a month or more to complete.

Three-toed sloths go to the ground to urinate and defecate about once a week, digging a hole and covering it afterwards. They go to the same spot each time and are vulnerable to predation while doing so. This may be relevant for maintaining the ecosystem in the sloths' fur. Individual sloths tend to spend the bulk of their time feeding on a single "modal" tree; by burying their excreta near the trunk of that tree, they may help nourish it. Recent research shows that moths, which live in the sloth's fur, lay eggs in the sloth's feces. When they hatch, the larvae feed on the feces, and when mature fly up onto the sloth above.

### Reproduction

Pale- and brown-throated species mate seasonally, while the maned sloth breeds at any time of year. The reproduction of pygmy three-toed sloths is unknown. Litters are of one newborn only, after six months' gestation for three-toed, and 12 months' for two-toed. Newborns stay with their mother for about five months. In some cases, young sloths die from a fall indirectly because the mothers prove unwilling to leave the safety of the trees to retrieve the young. Females normally bear one baby every year, but sometimes sloths' low level of movement actually keeps females from finding males for longer than one year. Sloths are not particularly sexually dimorphic and several zoos have received sloths of the wrong sex.

The average lifespan of two-toed sloths in the wild is 20 years, and up to 30 in captivity.

## In the Universe

The best known sloth to appear in the franchise is Tony.