Swimming Anteater
The swimming anteater, Myrmevenarius amphibius, is a semiaquatic mymecophagid anteater from Dougal Dixon's After Man: A Zoology of the Future. It lives in South American tropical forest wetlands.

Land-dwelling animals that have taken to an aquatic mode of life have usually done so initially to escape land-dwelling predators. This is probably why the water ant has taken to building its huge nest on rafts in swamps and quiet backwaters. However, in their new mode of life the ants are still vulnerable to the swimming anteater, which has evolved in parallel with it. This species of anteater lives solely on water ants, and to reach them undetected it attacks the nest from below, ripping through the waterproof shell with its clawed paddles. Since below the waterline the nest is made of discrete chambers that can rapidly be made watertight in an emergency, little damage is done to the colony as a whole. The ants drowned in an attack, however, are enough to feed the anteater.