why are ant-eaters nicknamed anti-bears?

Answer 1

not anti-bears, just ant-bears. The first part is obvious, because they eat ants. The second part is because they supposedly resemble bears (which they would only if you had a very vivid imagination!)

Answer 2

that is the Spanish name ,ursu armigaro ,
=ant bear

we call it an ant eater .
but they look kind of like a bear ,but they got huge claws ,like a sloth

and they stand up on their hind legs and growl at you when you get close
we had one in the garden
a dangerous animal