What animal has the longest arms in the world?

The Humpback Whale!  The humpback whale's common name comes from the shape of its dorsal (back) fin and the way it looks when the animal is diving. Its scientific name, Megaptera, means, "large-winged" and refers to its long, white, wing-like flippers that are often as long as one-third of the animal's body length.  Their flippers can grow up to 16 feet (5 m) long, which is the largest appendage in the world.