Mantis shrimps, or stomatopods, are marine crustaceans of the order Stomatopoda. Some species have specialised calcified "clubs" which can strike with great power,others have sharp forelimbs used to capture prey. They branched from other members of the class Malacostraca around 400 million years ago.
Mantis shrimps typically grow to around 10 centimetres (3.9 in) in length. A few can reach up to 38 cm (15 in).
The largest mantis shrimp ever caught had a length of 46 cm (18 in) and was caught in the Indian River near Fort Pierce, Florida, in the United States.