This is a Mantis Shrimp (order Stomotapoda) and is a marine crustacean found in most tropical and subtropical seas, mostly in the Indian and Pacific oceans between Hawaii and eastern Africa. They are also known as Sea Locusts, in ancient Assyrian records, Prawn Killers in Australia, and also as Thumb Splitters, due to their powerful claws that are used to attack and kill prey, as well as being capable of breaking through aquarium glass in captive situations.
Mantis Shrimp can average about 30cm long, with specimens of 38cm even recorded, and appearing in a variety of colours ranging from shades of brown to bright neon colours. They burrow intricate tunnels into sea bed and decaying coral, waiting for prey to wander past as opposed to actively hunting like other crustaceans.
There are about 400 species, commonly seperated into two distinct groups; Spearers (possessing spiny appendages topped with barbs, used to stab and snag prey), and Smashers (a more developed club-claw and rudimentary spear used to bludgeon and smash prey). Both varieties have rapidly unfolding and swinging raptorial claws. They can strike so rapidly that they produce 1,500 newtons of instantaneous force, and a second strike in the form of a cavitation bubble which also produces a significant force when collapsing, forming a shock wave that can be enough to stun or kill prey even if the physical impact misses. This bubble collapse also produces a sonoluminescence, producing a minute amount of light and high temperature too small to be measured by scientific equipment.
Mantis shrimp are noted to have powerful eyesight, able to differentiate between different types of coral, prey species and predators. Their keen eyesight also plays a factor in mating, where the shrimp actively fluoresce to attract a mate. The fluorescence also is also used in communication.
One species of mantis shrimp, Nannosquilla decemspinosa, have been known to flip into a crude wheel and roll in shallow areas into deeper water. Some observations found specimens to roll up to 2 metres.
This photo was taken by Gary Cranitch, and Highly Commended in the New Scientist Eureka Prize for Science Photography. http://australianmuseum.net.au/image/Mantis-Shrimp