Fleeper

Fleepers are strange little critters from Yoshi's Island DS that are reminiscent of the Frog Pirates from Super Mario World 2: Yoshi's Island, but look and act differently. Two immediately noticeable differences is that they're yellow, and look more like fleas than actual frogs (which is probably how they got their names). They also bear a passing resemblance to a prairie chicken. Additionally, instead of lashing out with their tongues in an attempt to steal the baby you're carrying, they attack by trying to jump on top of you. With their long and springy hind legs, they can jump up into the top screen. There also seems to be some more clumsier Fleepers that only make short hops, and keep continuosly falling to their bottoms after jumping.

Trivia
Fleepers are named similarly to the Super Paper Mario Pixl Fleep.