Ah... In cantonese we call it 攋尿蝦(pissing shrimp). Why pissing? Because they tend to shoot a jet of water when picked up.
There are around 400 species of mantis shrimp worldwide, and they are categorized based on the types of claw they possess.
So what's so special about this shrimp? Er...sorry, crustacean.
I watched Animal Planet several years back and there was this documentary listing the top ten loudest animals of the animal kingdom. And surprisingly this little crustacean topped the chart. Why loudest?
To understand that we must first understand the source of the sound, the claws. The claws of mantis shrimp are really special, and they use it to smash the life out of their prey, literally. They strike their prey by rapidly unfolding and swinging their raptorial claws at the prey, and are capable of inflicting serious damage on victims significantly greater in size than themselves.
Apart from its powerful claw, the mantis shrimp also possesses the most advanced eye of any animals on Earth. Its compound eyes sit on independently moving stalks, and they can see in twelve colours (humans see in only three). Humans can't distinguish between polarized and nonpolarized light, whereas the eyes of a mantis shrimp can detect circular polarized light which can’t be detected by any other creature.
But even our best quarter-wave plates can only detect circular polarized light in a few colors. The quarter-wave plates of mantis shrimps work across the visual spectrum, for any color of CPL.