The mantis shrimp are tropical predators of crabs, shrimp, and mollusks. The mantis shrimp has a second pair of appendages that is enlarged and have a movable finger. The finger is able to be extended rapidly to kill and capture prey or for defense. Mantis shrimp can spear or smash their prey (pretty violently). Mantis shrimp that spear usually prey on invertebrate marine animals like shrimp or fish. Mantis shrimp that smash usually prey on hard bodied animals like snails, crabs, and clams. They stalk their prey and then sneak up and literally smash them to bits. Their smash is so powerful that it could crack a glass aquarium.