The three-toed sloth is not well informed about the outside world. On a scale of 2 to 10, where 2 represents unusual dullness and 10 extreme acuity, Beebe (1926) gave the sloth’s senses of taste, touch, sight and hearing a rating of 2, and its sense of smell a rating of 3. If you come upon a sleeping three-toed sloth in the wild, two or three nudges should suffice to awaken it; it will then look sleepily in every direction but yours. Why it should look about is uncertain since the sloth sees everything in a Magoo-like blur. As for hearing, the sloth is not so much deaf as uninterested in sound. Beebe reported that firing guns next to sleeping or feeding sloths elicited little reaction. And the sloth’s slightly better sense of smell should not be overestimated. They are said to be able to sniff and avoid decayed branches, but Bullock (1968) reported that sloths fall to the ground clinging to decayed branches “often”.
How does it survive, you might ask.