Evolution totally gypped the snake. It's all like "Hey skinny lizard, get rid of those legs all together. Ooooh, you'll be sneaking up on the little mousies. They won't know what hit 'em." And snakes are like "Fuck, yeah! Ditch the limbs, natural selection!" Then every encounter with a bigger animal sucks because they can't run away.
Meanwhile otters are like, "Hey lookit me! I'm eatin' oysters on ma belly! Whoop!"