Weird Wonder Wednesday: Mantis Shrimp

Stomatopods, commonly known as "mantis shrimp," are crustaceans characterized by large, raptorial forelimbs.  The forelimbs can be employed with the dactyl closed to make smashing attacks against the shells of armoured prey, or with the dactyl open to spear soft-bodied prey.  This dactyl strike is one of the fastest of all known animal movements.  It can be completed in as little as five milliseconds under water, generating enormous percussive force, comparable to the impact of a .22 calibre bullet, and has been known to shatter aquarium glass.

Stomatopods are territorial and pugnacious, and frequently fight amongst themselves.  Keeping two stomatopods unseparated in a tank will usually result in one of them killing the other.  This video demonstrates the effectiveness of the stomatopod's strike.

Not only do mantis shrimp possess a remarkably efficient attack mechanism, they have the most sophisticated and complex eyes in the animal kingdom.  They are able to see objects with three different parts of each eye, giving them trinocular vision and depth perception with each of their eyes.  They are also able to see in the infrared and ultraviolet wavelengths.

The Burgess Shale animal, Yohoia tenuis has many features in common with living stomatopods, including forelimbs similar to the raptorial appendages of the mantis shrimp.  A large number of fossil brachiopods that I've collected from the Middle Cambrian Deadwood Formation in South Dakota have shell damage identical to that of modern shells that have been attacked by stomatopods.  No other known Cambrian predator could have caused such damage, and Yohoia may have been responsible, making it the earliest known durophagous (smashing) predator.

The aggressive nature of mantis shrimp, combined with their devastatingly effective forelimb strike and superior vision make these creatures something you wouldn't want to stumble upon in a dark cave, thus make excellent monsters for your players to encounter in their next subterranean delve.