Sloth

 "Sloth"

 World’s slowest animal

The Sloth's weight is 11.2 ounces at birth.

How big can a Sloth get:-

Brown-throated sloth: 42 – 80 cm.

Maned sloth: 55 – 75 cm.

Pale-throated sloth: 50 – 75 cm.

Sloths sleep up to:  15-18 hours per day.

About:-

Sloths are a group of arboreal Neotropical xenathran mammals, constituting the suborder Folivora. Noted for slowness of movement, they spend most of their lives hanging upside down in the trees of the tropical rain forests of South America and Central America. They are considered to be most closely related to anteaters, together making up the xenarthran order Pilosa. There are six extant sloth species in two genera – Bradypus (three–toed sloths) and Choloepus (two–toed sloths). Despite this traditional naming, all sloths actually have three toes on each rear limb, although two-toed sloths have only two digits on each forelimb. The two groups of sloths are from different, distantly related families, and are thought to have evolved their morphology via parallel evolution from terrestrial ancestors. Besides the extant species, many species of ground sloth ranging up to the size of elephants Megatherium both North and South America during the Pleistocene epoch. However, they became extinct during the Quaternary extinction event around 12,000 years ago, together with most large bodied animals in the New World. The extinction correlates in time with the arrival of humans, but climate change has also been suggested to have contributed. Members of an endemic radiation of Caribbean sloths formerly lived in the Greater Antilles. They included both ground and arboreal forms which became extinct after humans settled the archipelago in the mid-Holocene, around 6,000 years ago.

Sloths are so named because of its very low metabolism and deliberate movements, sloth being related to the word slow. This supports their low-energy diet of leaves and avoids detection by predatory hawks and cats that hunt by sight. Sloths are almost helpless on the ground but are able to swim. The shaggy coat has grooved hair that is host to symbiotic green algae which camouflages the animal in the trees and provides it nutrients. The algae also nourishes sloths moths, some species of which exist solely on sloths.

Sloths belong to the superorder Xenartha, a group of placental mammals  believed to have evolved in the continent of South America around 60 million years ago. One study found that xenarthrans broke off from other placental mammals around 100 million years ago. Anteaters and armadillos are also included among Xenarthra. The earliest xenarthrans were arboreal herbivores with sturdy vertebral columns, fused pelvises, stubby teeth, and small brains. Sloths are in the taxonomic suborder Folivora of the order Pilosa. These names are from the Latin 'leaf eater' and 'hairy', respectively. Pilosa is one of the smallest of the orders of the mammal class; its only other suborder contains the anteaters.

Evolution:-

The common ancestor of the two existing sloth genera dates to about 28 million years ago, with similarities between the two- and three- toed sloths an example of convergent evolution  to an arboreal lifestyle, “one of the most striking examples of convergent evolution known among mammals”. The ancient Xenarthra included a much greater variety of species, with a wider distribution, than those of today. Ancient sloths were mostly terrestrial, and some reached sizes that rival those of elephants, as was the case Megatherium. 

Sloths arose in South America during its long period of isolation and eventually spread to a number of the Caribbean islands as well as North America. It is thought that swimming led to oceanic dispersal of pilosans to the Antilles by the Oligocene, and that the Pilometanastes mylodontid Thinobadistes were able to colonize North America about 9 million years ago, well before the formation of the Isthmus of Panama. The latter development, about 3 million years ago, allowed megatheriids and nothrotheriids to also invade North America as part of the Great American Interchanga. Additionally, the nothrotheriid Thalassocnus of the west coast of South America became adapted to a semiaquatic and eventually perhaps fully aquatic marine lifestyle. In Peru and Chile, Thalassocnus entered the coastal habitat beginning in the late Miocene. Initially they just stood in the water, but over a span of four million years they eventually evolved into swimming creatures, becoming specialist bottom feeders of seagrasses, similar to extant marine sirenians. 

Both types of extant tree sloth tend to occupy the same forests; in most areas, a particular species of the somewhat smaller and generally slower-moving three-toed sloth (Bradypus) and a single species of the two-toed type will jointly predominate. Based on morphological comparisons, it was thought the two-toed sloths nested phylogenetically within one of the divisions of the extinct Caribbean sloth. Though data has been collected on over 33 different species of sloths by analyzing bone structures, many of the relationships between clades on a phylogenetic tree were unclear. Much of the morphological evidence collected to support the hypothesis of diphyly has been based on the structure of the inner ear.

Sloths are one of the slowest animals on the face of the earth, but they are also one of the smartest animals. They are funny, cute and very noisy.

Sloths can charge humans if they feel threatened, according to the San Diego Zoo, which adds that the tree dwellers have sharp, canine like teeth.

Well at least not with two-toed sloths — they are known to be quite aggressive and can do some serious damage with their claws. Three-toed sloths are generally more easygoing, but still don't appreciate having human hands all over them.

Sloths have an extremely low metabolic rate, which means they move at a languid, sluggish pace through the trees. On average, sloths travel 41 yards per day—less than half the length of a football field!

Some three-toed sloths may carry over 120 moths on their bodies. As a result of all of this, sloths are some of the worst-smelling creatures on Earth. The hoatzin is sometimes called the "stink bird", because of the smell of manure that emanates from its body.

Birth of sloth:-

Brown-throated sloth: 152 – 243 days

Maned sloth: 150 days

Pale-throated sloth: 183 days

A recent study of the sloth's fur revealed it is home to a range of fungi that are bioactive against strains of the parasites that cause malaria and Chagas disease, and against some human breast cancer cells.

Sloths are blind in bright daylight. They have a very rare condition called rod monochromacy which means that they completely lack cone cells in their eyes. As a result all sloths are color-blind, can only see poorly in dim light and are completely blind in bright daylight.

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