The name mantis shrimp comes first of all from their resemblance to their distant arthropod cousins – the praying mantis insects – because of the way that they hold their large main claws in an upright position, poised to strike. Secondly, their overall body shape resembles their close arthropod cousins, the shrimp. However mantis shrimp belong to the Class Stomatopoda, while shrimp belong to the Class Decapoda.
Unlike true shrimp, the main claws of the mantis shrimp do not open like pincers. The shapes of those large claws define two types of mantis shrimp: the smashers and the spearers. The claws of the smashing mantises are club-like and used to break open shelled molluscs or other crustaceans. The claws of the spearing mantises are edged with long, wicked spikes which they use to impale fish prey. Those claws strike with such speed (75 feet per second) that not only does the claw itself deliver a blow, but cavitation in the water creates a shock wave that causes additional damage. Even if the claw-strike misses, the shock can stun and immobilize the prey.
These mantis shrimp also have the most complex eyes in the animal kingdom. Those eyes include between 12 to 16 types of photoreceptors, compared with 4 photoreceptors in humans. The photoreceptors in the mantis shrimp extend through not only typical color ranges, but all the way into the ultraviolet range. Furthermore, some of the sensors are specialized for polarizing the light to eliminate distracting reflections. The eyeballs may be rounded or elongated, and those sensors are arrayed on them to enable three-dimensional sight for excellent depth perception. The speed of their claws, coupled with their superior eyesight, makes the 480 species of mantis shrimp very capable predators.