Gonodactylus chiragra

All stomatopods are either spearers or smashers. G. Chiragra is a smasher which means that the heel on their second pair of thoracic appendages is greatly enlarged, forming a club that is used to smash prey.[6] When a target is spotted, G. Chiragra strike powerfully and quickly in one of the quickest punches in all of nature.[7] Common targets for eating are snails, hermit crabs, and clams, but bigger animals are sometimes targeted such as mollusks and other crustaceans.[8] G. Chiragra are one of the largest smashers and employ a unique fighting strategy in which they circle around the target and aim at the head.[6] This is thought to have developed as a result of intense competition for suitable burrows among stomatopods.[6]

The species is considered one of the most aggressive species of mantis shrimp and when in captivity, routinely strike glass walls and air tubes in the aquarium.[1]

Seeing underwater is very different because in the ambient light there is strong spectral variations that affect color vision.[9] The eyes of G. Chiragra are some of the most unique in all of the animal world because they are sensitive to linear polarization.[10] Living underwater, this provides many benefits to them including increased contrast enhancement, ability to see polarization reflecting prey, and better navigation among the light-scattered ocean environment.[10]

The eyes themselves are large stalked apposition compound eyes and have two defining features that affect their complexity.[10] First is their rotational ability. The eyes move completely independent of each other and one eye only is enough for catching prey.[11] Second is the presence of a midband, a large strip of specialized ommatidia (clusters of photoreceptor cells) that divides each eye equally into two segments.[12] The midband contains specialized polarization receptors in rows five and six. In row 2D, photoreceptors have unidirectional microvilli which makes them sensitive to linear polarized light.[10] The midband is also responsible for binocular distant vision.[11]

Although their eyes are incredibly complex among animals, G. Chiragra are one of the few species of mantis shrimp that do not have polarized body markings.[10] This offers them one less form of communication and it is thought that evolution of deadly weapons was preferred to body signals because of their restricted habitat.[10] (see “claws” above)