Английская Википедия:Gonodactylus chiragra
Шаблон:Short description Шаблон:Speciesbox
Gonodactylus chiragra is a medium to large mantis shrimp that is distributed widely throughout the West Indo-Pacific.
Taxonomy
The synonymy of G. chiragra remains unclear because all members of Gonodactylus have been confused with G. chiragra at some point.[1] This species also displays a large amount of variation, which has made classification even more difficult.[2] Newer research by Manning has resulted in the discovery of several new species that were previously thought to be G. chiragra.[3]
Description
The species typically grows to a maximum length of 105 millimetres and is sexually dimorphic.[4] Males range in color from brown to a dark green, and females from a grey/green to white.[5]
Claws
All mantis shrimp (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]
Eyes
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 (see "Claws" above) was preferred to body signals because of their restricted habitat.[10]
Distribution and habitat
The species is widely distributed in the western Indo-Pacific.[3] It occurs in shallow water in the upper intertidal zone around boulders and coral heads where prey is available.[13] G. chiragra are burrowers, but usually do not construct their own shelters. Instead, they inhibit rocky cavities that are either natural or created by other animals such as mollusks.[1] However, they are equipped to erode the material of the burrow so that it perfectly fits their body shape.[1] Burrows serve many purposes, including protection, lookouts for finding prey, consuming prey, mating, and keeping eggs safe.[1] G. chiragra are active during the day and often close off the entrance to their shelter at night using bits of sand and rocks.[8]
References
- ↑ 1,0 1,1 1,2 1,3 1,4 Шаблон:Cite journal
- ↑ Шаблон:Cite book
- ↑ 3,0 3,1 Шаблон:Cite journal
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ 6,0 6,1 6,2 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ 8,0 8,1 Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ 10,0 10,1 10,2 10,3 10,4 10,5 Шаблон:Cite journal
- ↑ 11,0 11,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
External links
- Photos of G chiragra on Roy's List of Stomatopods for the Aquarium
- Video demonstrating the quickness of G. chiragra
