Panama Adventure - Sloths

Everyone loves sloths, right? We were lucky enough to see and photograph a number of them. Mostly the BROWN-THROATED THREE-TOED SLOTH.

I have to tell you a story about the sloth in the first photo. As we were just starting a hike, we saw this sloth high in a cecropia tree, hanging upside down and slowly scratching itself. I got some good photos, and we continued onward. When we came back down the same trail about two hours later, the sloth was still hanging there, and was STILL scratching itself. A good scratch cannot be rushed, I suppose.

Why are sloths so slow? This question has puzzled biologists for centuries. Way back in 1749, when sloths were first described in scientific literature (by Georges Buffon), he referred to them as: "the lowest form of existence." This is obviously incorrect because sloths have thrived for 64 million years. They are very well adapted for their lifestyle.

First, sloths are completely colorblind, due to a genetic condition that showed up in their ancestors millions of years ago. They see poorly in dim light, and hardly at all in bright daylight. Very few tree-climbing animals are colorblind, and this condition requires that they move slowly and cautiously.

But that's not all. Sloths have extremely slow metabolism. In fact, their metabolism is so slow that they are unable to regulate their body temperature internally, like other mammals can. They regulate their temperature behaviorally, like a cold-blooded animal does, by basking in the sun when they are cool and moving to the shade when hot. Unlike other mammals, a sloth's internal body temperature can fluctuate as much as 20 degrees F during the day (this would be fatal to a human).

These factors, among others, result in an extremely slow-moving animal. But this isn't a bad thing—it's simply a different way of surviving. Sloths are very good at what they do!

The last photo is a HOFFMANN'S TWO-TOED SLOTH, which we saw in a sloth sanctuary. We only saw one of these in the wild, and it was not in position for good photos.

Photo Credits:
All sloth photos - Stan C. Smith