Armadillos have terrible vision. In 1913, American zoologists Horatio H. Newman and J. Thomas Patterson wrote, “The eyes [of the nine-banded armadillo] are rudimentary and practically useless. If disturbed an armadillo will charge off in a straight line and is as apt to run into a tree trunk as to avoid it.”

The three-toed sloth isn’t much better. “If an infant sloth is placed five feet away from its mother on a horizontal branch at the same level, at once the young sloth begins to cry, the mother shows that she heard it calling and turns her head in all directions. Many times she looks straight in the direction of her offspring but neither sight, hearing nor smell apparently avail anything,”