Two Toed Sloth Research Paper

The sloths of today are different from their ancient ancestors. They have shrunk in size and speed in comparison to the sloths the past. The ancient Megatherium americanum measured roughly 4 meters long from tail to head and had a shoulder height of 2.25 meters (Argot, 2008). A modern-day descendant of M. americanum is the Southern two-toed sloth, also known as Linnaeus’s two-toed sloth (Choloepus didactylus) and it pales in comparison to its ancestor in size. Of course, the M. americanum isn’t the only ancestral sloth, but it is one of the only Megatharium species that is described in detail (Pujos & Salas, 2004). Both the ancient and modern sloths are native to South America, though there is a species that is native to North America—Eremotherium

A relative of the Southern two-toed sloth is the three-toed sloth (Bradypus tridactylus). Generally, the three-toed sloth is smaller than its two-toed cousin; measuring at about 18 inches in length. Both species sleep for about 18 hours per day. When awake, they spend most of their day eating leaves. However, unlike the two-toed sloth, the three-toed sloth is an agile swimmer. Sloths are able to crawl on land, but they are painfully slow. They crawl on the ground at a speed of 2 meters/minute and climb at 3 meters/minute. They spend most of their lives in trees. However, they usually only climb about 125 meters/day. All modern sloths are herbivores. A sloth’s fur can house an entire ecosystem. Beetles and other small insects can be found living in its fur. There are also species of moths that depends on the sloth’s decent to the ground for its life cycle (Bradley, 1982). The mother moth lays her eggs in the excrements of the sloth and returns to her home in the sloth’s fur. Once the eggs hatch and the larvae become moths, they also find their own sloth to live on and repeat the

C. didactylus has 5 to 7, while B. tridactylus has 8 or 9 (BioMed Central, 2011). When compared to skeletons of related species to both sloths (e.g. anteaters and armadillos), none of the related species showed an unusual amount of cervical vertebrae. However, manatees have only 6 cervical vertebrae (Hautier, Weisbecker, Sanchez-Villagra, Goswami, & Asher, 2014). While all mammals need 7 cervical vertebrae to survive, it is remarkable to see these three species survive with their abnormal number of cervical vertebrae. As we discussed in class, having any more or less than 7 cervical vertebrae can be deadly to the organism. It is hypothesized that the low metabolic and activity rates of sloths protected them from the harmful effects from having an abnormal amount of cervical vertebrae (Varela-Lasheras, et al.,