As their name suggests, they have the ability to leap long distances, and they'll use this to their ability while capturing prey or defending themselves. Once they get close enough to their selected target, they'll tear away with their talons.
They also seem to have venom in their body, which they'll spew out at any opponents, greatly harming them. Because they are easily killed, they'll commonly hunt in packs.
A more aggressive and powerful type of Hopper, the Alpha Hopper, appears only once in the entire game.