Gonodactylus chiragra is a medium to large mantis shrimp that is distributed widely throughout the West Indo-Pacific.
| Gonodactylus chiragra | |
|---|---|
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Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Stomatopoda |
| Family: | Gonodactylidae |
| Genus: | Gonodactylus |
| Species: | G. chiragra
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| Binomial name | |
| Gonodactylus chiragra (Fabricius, 1781)
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| Synonyms | |
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Squilla chiragra Fabricius, 1781 | |
Taxonomy
editThe 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
editThe 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
editAll 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
editSeeing 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
editThe 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
edit- ^ a b c d e Manning, R.B. (1981). "Stomatopod Crustacea of Vietnam: the legacy of Raoul Serène". Crustacean Research, Special. 4: 71–75.
- ^ Gardiner, J, ed. (1903). "Marine Crustaceans. VIII. Stomatopoda, with an account of the varities of Gonodactylus chiragra". The fauna and geography of the Maldive and Laccadive archipelagoes. Vol. 1. Cambridge University Press. pp. 444–445.
- ^ a b Moosa, Mohammad (2000). "Marine Biodiversity of the South China Sea: A Checklist of Stomatopod Crustacea" (PDF). The Raffles Bulletin of Zoology. 8: 420.
- ^ "Gonodactylus chiragra". www.sealifebase.ca. Retrieved 2020-11-12.
- ^ Ahyong, Shane (2001). "Revision of the Australian Stomatopod Crustacea" (PDF). Records of the Australian Museum. 26: 67–71.
- ^ a b c Caldwell, Roy L.; Dingle, Hugh (1976). "Stomatopods" (PDF). Scientific American. 234 (1): 80–89. Bibcode:1976SciAm.234a..80C. doi:10.1038/scientificamerican0176-80. JSTOR 24950262 – via JSTOR.
- ^ Schiff, H (1989). "Visual input patterns correlated to behavior and habitat of the mantis shrimp Gonodactylus". Comparative Biochemistry and Physiology Part A: Physiology. 94: 75–87. doi:10.1016/0300-9629(89)90788-3.
- ^ a b Caldwell, Roy. "Gonodactylus Chiragra". Roy's List of Stomatopods for the Aquarium.
- ^ Loew, E.R.; Lythgoe, J. (1985). "The ecology of color vision". Endeavor. 9 (4): 170–174. doi:10.1016/0160-9327(85)90073-0. PMID 2419110 – via Elsevier Science Direct.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e f Kleinlogel, S; Marshall, J. (2006). "Electrophysiological evidence for linear polarization sensitivity in the compound eyes of the stomatopod crustacean Gonodactylus chiragra" (PDF). The Journal of Experimental Biology. 209 (21): 4262–4272. doi:10.1242/jeb.02499. PMID 17050841. S2CID 7205109.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b Schiff, Helga (2009). "Influence of different eye regions on striking, size discrimination and habituation in mantis shrimps". Italian Journal of Zoology. 63 (2): 139–148. doi:10.1080/11250009609356122.
- ^ Marshall, J; Cronin, T; Kleinlogel, S. (2007). "Stomatopod eye structure and function: A review". Arthropod Structure and Development. 36 (4): 420–448. doi:10.1016/j.asd.2007.01.006. PMID 18089120.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Ahyong, Shane (2004). "Stomatopod Crustacea from Anambas and Natuna Islands, South China Sea, Indonesia" (PDF). The Raffles Bulletin of Zoology. 11: 62.
External links
edit- Photos of G chiragra on Roy's List of Stomatopods for the Aquarium
- Video demonstrating the quickness of G. chiragra