The Fearsome Mantis Shrimp

Mantis shrimp (or stomatopods) are marine crustaceans, being members of the order Stomatopoda. They can reach up to 30 cm in length and appear in a mutlitude of colours, from shades of drab browns to a kaleidoscope of bright neon colours. Around 400 species of Mantis shrimp have currently been described worldwide; all living species are in the suborder Unipeltata. Although they are common animals and among the most important predators in many shallow, tropical and sub-tropical marine habitats, they are poorly understood as many species spend most of their life secretly hiding away in burrows and holes.

They are commonly separated into two distinct groups, determined by the manner of claws they possess: 'spearers' or 'smashers'. Spearers are armed with spiny appendages topped with barbed tips, used to stab and snag prey. Smashers, on the other hand, possess a much more developed 'club' and a more rudimentary spear (which is nevertheless still quite sharp); the club is crudely used to bludgeon and smash their meals apart.

It is these immensely powerful claws, in which they use to attack and kill prey by spearing, stunning, or dismemberment, that is no doubt the most impressive fact about these wonderful creatures. Although it can happen very rarely, some of the larger species of Mantis shrimp are fully capable of breaking through aquarium glass with a single strike from their claws.

Both groups strike by rapidly unfolding and swinging their raptorial claws at the prey and are capable of inflicting fatal damage on victims significantly greater in size than themselves. With smashers, their clubs are employed with blinding quickness, with an acceleration of 10,400 G (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 metres per second from a standing start! To put that into some form of context, it is about the same acceleration of a .22 calibre bullet!

Additionally, because they strike so rapidly, they generate 'cavitation bubbles' between the appendage and the striking surface. The collapse of these bubbles produces measurable forces on their prey, in addition to the instantaneous forces that are caused by the impact of the appendage against the striking surface. Which means that the prey is actually hit 'twice' by a single strike; first by the claw and then by the collapsing bubbles that immediately follow. Even if the initial strike misses the prey, the resulting shock wave can be enough to kill or stun the prey in its own right.

Smashers use their appendages to attack snails, crabs, molluscs and rock oysters; their blunt clubs enable them to simply bludgeon and crack the shells of their prey into pieces. Spearers, on the other hand, prefer the meat of softer animals, like fish, which their barbed claws can more easily slice and snag. Pound for pound the Mantis shrimp undeniably has to be the true 'heavyweight champion of the world' when it comes to punching! Truly awesome power!