How to survive if you're slow as a sloth?
For evolution, the survival of the fittest is extremely important. An animal's evolution can be seen as a sort of competition, with less "fit" animals dying off before they are able to reproduce and pass on genes that aren't favorable for adapting to their environment. The evolution of each lifeform has led them to develop different characteristics that suit their specific needs and niches in the world.
Some animals have evolved to be incredibly fast, able to outrun predators or prey. Others have developed powerful muscles or sharp claws that help them catch food or defend themselves. But how do you survive if you're not fast or strong?
It turns out that slowness can also be an advantage in some environments. Most people already know that sloths are the slowest mammals on the planet, with a maximum speed of about 4 meters per hour. To understand why sloths are not as easy prey as they seem at first glance, we first need to understand how their natural predators hunt and what they have in their arsenal in order to effectively detect and catch prey.
As sloths spend most of their life high up on a tree, their main predators are jaguars and eagles. Jaguars have binocular vision, just like humans. But unlike humans, they are half color blind (they can see blue and green). Binocular vision has a lot of advantages for animals. It allows to judge distances very accurately. This is because each eye sees an object from a slightly different angle. When the two images are combined in the brain, the object appears to be three dimensional. This is very important for hunting animals, as it allows them to determine the distance to their prey, as well as to catch even the slightest movement. Since sloths don't move much or since they move very slowly it is a lot harder for predators to notice them. Ironically, this is what wild cats use to sneak up on their prey, they move very slowly towards their victim, using motion disguise to seem motionless to the observer.
What about eagles? Eagles have not only binocular vision, but also the sharpest vision of any other animal on the planet. Simply put, their eyes provide a picture with very good resolution (An eagle's eye has over a million cone cells per square millimeter, whereas the eye of a human only has about 200,000). But what actually makes them such effective predators is their ability to distinguish colors.
Ironically, this is what makes them a lot less effective when spotting sloths. Birds of prey rely heavily on the color difference between an object and the environment, and they are 10 times less likely than humans to detect an object if it is the same or similar color to its environment.
During their evolution, sloths have developed very long and thick hair all over their bodies, which constitutes a separate ecosystem for a wide range of insects, plants and fungi, including one special alga from the genus Trichophilus. Recent studies have shown that sloths have a symbiotic relationship with the aforementioned algae, they provide shelter and water that is absorbed by the thick fur and in return makes the sloth green and virtually indistinguishable from predators. The fact that most of the flora and fauna living in sloths fur, including algae, is passed over to newborns during their first couple of weeks after birth confirms the fact of this interesting symbiotic relationship.
While it is sometimes puzzling how some animals, such as the sloth, were able to survive until modern times, while others, more cruel, fast and cunning animals became extinct, if we take a closer look, we understand that these animals are not as vulnerable as they seem. A sloth can move slowly, but movement is not his primary defense method. Camouflage is a great way to go undetected. And this is where sloths have become experts over a long period of their evolution.