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Kiwa(crustacean)

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Kiwa
Kiwa hirsuta
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Anomura
Superfamily: Chirostyloidea
Family: Kiwaidae
Macpherson, Jones & Segonzac, 2006
Genus: Kiwa
Macpherson, Jones & Segonzac, 2006

Kiwais agenusof marinedecapodsliving at deep-seahydrothermal ventsandcold seeps.The animals are commonly referred to as "yeti lobsters" or "yeti crabs”, after the legendaryyeti,because of their "hairy" or bristly appearance.[1]The genus is placed in its own family,Kiwaidae,in the superfamilyChirostyloidea.[2]The genusKiwais named after the god of shellfish in Polynesian mythology.[1]

Population ofKiwaaround ahydrothermal vent

Based on the presence ofsulphur-oxidisingbacteria on thesetaeof bothK. hirsutaand the new South West Indian Ridge species, they may both feed on bacteria in addition to scavenging.[3]ForK. puravida,the bacteria have been identified and the feeding behaviour observed, as well as a cyclical rhythmic motion of the crab documented that is suspected to increase the flow of methane andhydrogen sulfide,the bacterial food, towards the bacteria.[4]The two sexes of the new South West Indian Ridge species prefer different temperatures, with males seeming to prefer warmer water and egg-carrying females and juveniles preferring the coldest.[3]Chemosynthetic bacteria is growing which is affecting the habitat for yeti crabs.

Because yeti crabs live in extreme environments like cold seeps and hydrothermal vents, the species has adapted certain behaviors and qualities to aid their survival. These adaptations include the crab's growth of their setae,[5]propodus[6]and claws.[7]The internal anatomy, diet, behaviors and adaptations of the yeti crab are outlined below.

Range and habitat

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Various species of yeti crabs have been found at varying locations. Four species have been described:Kiwa hirsutadiscovered in 2005 on thePacific-Antarctic Ridge,[8]Kiwa puravidadiscovered in 2006 at cold seeps in the East Pacific (all other species are from hydrothermal vents),[9][10]Kiwa tyleri,known colloquially as the "Hoff crab", from theEast Scotia Ridge,[11][12]andKiwa araonaefrom the Australian-Antarctic Ridge.[13]Two similar butundescribed speciesare known from vents on theSouth West Indian Ridgeand at theGalápagosrespectively.[10][14]Analysis of DNA has confirmed the distinction of the species, them having diverged from each other millions of years ago.[15][3]The third undescribed species ofKiwawas discovered in 2010 in the Atlantic sector of the Southern Ocean at vents on the East Scotia Ridge. Compared with the first two species, it has proportionally much shorter chelae, with the majority of the bacteria-growing setae concentrated on the ventral carapace.[16][3]

Kiwa araonae's discovery added about 6,500 kilometers to the Kiwaidae's known range on mid-ocean ridges. From morphological observations and molecular phylogenetic investigations, K. araonae and K. puravida are closely related. AlthoughK. araonaeandK. puravidaare separated by around 12,000 kilometers, they are similar.[17]Research pertaining to fossils around the Eocene-Oligocene boundary in the eastern Pacific suggests a decrease in deep temperatures and increased ventilation in each habitat may have influenced species divergence. Likewise fossils found in the mid-Miocene (located in the tropical East Pacific), indicate that the evolution of one species of yeti crab, K. puravida, may coincide with lower deep sea temperatures.[16]

Diet

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The main dietary source of yeti crabs, symbiotic bacteria, reside on the hair-like appendages seen in this image.

Kiwa crustaceans play a crucial role in the deep-sea ecosystem, serving as primary consumers and contributing to the biodiversity within hydrothermal vent communities. The absence of sunlight at hydrothermal vents poses a challenge to how vent species obtain energy required to sustain life. Since sunlight cannot provide the necessary fatty acids and carbon isotopes necessary for their survival, yeti crabs rely solely on symbiotic bacteria as their main food source.[18]Yeti crabs feed on chemosynthetic bacteria that reside on hair-like setae on the outer appendages of the crustacean.[19]Other organisms, such asShinkaia crosnieriandRimicaris exoculataexhibit similar dietary patterns as the yeti crab.

Behaviors

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Feeding behavior

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Scientists have observed thatK. puravidahave a unique approach when it comes to farming food. This method has made the species become known as the "dancing crab".[4]Yeti crabs have been observed waving their claws around near cold seeps, which makes them appear as if they are dancing. This dance is actually a form of farming for the species. By waving their claws around, the crab stirs up water around the symbiotic bacteria living in the setae on their claws.[20]This ensures the bacteria are receiving enough chemicals that will provide energy to grow.[4][20]By growing their own food, the yeti crab has a readily available resource of food in the harsh environment of the deep sea.

Reproductive behavior

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Little is known about the mating behavior between yeti crabs. Much of what we know so far has been studied inKi puravida.[21]Scientists have found that male crabs exhibit larger claws than females, suggesting that antagonistic interactions may occur between males competing for a female mate.[4]This resembles a precopulatory guarding type mating system, which describes a set of mating behaviors found in decapods which consists of long interactions between a set of mates and higher levels of aggression in males.[21]In another species,K.tyleri,males were observed to be found in groups closest to hydrothermal vents, while females were seen further away from these dense areas. This may be because egg-bearing females need to escape the high levels of heat near vents and move to a colder area in order to protect the development of their eggs.[21]

Adaptations

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One adaptation of the yeti crab species is the growth of its setae to farm bacteria in the speciesK. puravida.[4]There is some variation regarding the different types and various states of setae. There are two different types of setae that are organized adjacent to one another. Rows of narrow and flexible setae enclose the rows of more restricted, thicker setae. Because females slightly deviate from the vent environment during egg fertilization and larval development, brooding females contain more deteriorated, brown setae, as a result of their reduced carapace health away from the vent environment.[22]

An additional adaptation found in the speciesKiwa (tyleri)is the formation of a spine on the propodus (the end of the crab leg). This is beneficial for yeti crabs because they help the crustacean to cling to steep chimneys of hydrothermal vents. The stout, compact build of the crab also helps it traverse hydrothermal vent environments.[23]

Scientists have found that male yeti crabs have larger claws than females, which may indicate that bigger claws are sexually selected for reproductive advantages.[21]Previous research has suggested the claws are a mechanism of protection as scientists observed yeti crabs fighting with their claws or waving their claws to fend off predators.[24]Bigger claws may also provide a better fitness advantage because they provide more surface area for symbiotic bacterial farming.[21]

References

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  1. ^abMacpherson E, Jones W, Segonzac M (2006)."A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacific-Antarctic Ridge"(PDF).Zoosystema.27(4): 709–723.
  2. ^Schnabel KE, Ahyong ST, Maas EW (February 2011). "Galatheoidea are not monophyletic - molecular and morphological phylogeny of the squat lobsters (Decapoda: Anomura) with recognition of a new superfamily".Molecular Phylogenetics and Evolution.58(2): 157–68.Bibcode:2011MolPE..58..157S.doi:10.1016/j.ympev.2010.11.011.PMID21095236.
  3. ^abcdRogers AD, Tyler PA, Connelly DP, Copley JT, James R, Larter RD, et al. (January 2012)."The discovery of new deep-sea hydrothermal vent communities in the southern ocean and implications for biogeography".PLOS Biology.10(1): e1001234.doi:10.1371/journal.pbio.1001234.PMC3250512.PMID22235194.
  4. ^abcdeThurber AR, Jones WJ, Schnabel K (2011)."Dancing for food in the deep sea: bacterial farming by a new species of Yeti crab".PLOS ONE.6(11): e26243.Bibcode:2011PLoSO...626243T.doi:10.1371/journal.pone.0026243.PMC3227565.PMID22140426.
  5. ^Thurber AR, Jones WJ, Schnabel K (2011)."Dancing for food in the deep sea: bacterial farming by a new species of Yeti crab".PLOS ONE.6(11): e26243.Bibcode:2011PLoSO...626243T.doi:10.1371/journal.pone.0026243.PMC3227565.PMID22140426.
  6. ^Thatje S, Marsh L, Roterman CN, Mavrogordato MN, Linse K (2015-06-24)."Adaptations to Hydrothermal Vent Life in Kiwa tyleri, a New Species of Yeti Crab from the East Scotia Ridge, Antarctica".PLOS ONE.10(6): e0127621.Bibcode:2015PLoSO..1027621T.doi:10.1371/journal.pone.0127621.ISSN1932-6203.PMC4480985.PMID26107940.
  7. ^Azofeifa-Solano JC, Pereira OS, Cowell EJ, Cordes EE, Levin LA, Goffredi SK, et al. (2022)."Sexual dimorphism in the methane seep-dwelling Costa Rican yeti crab Kiwa puravida (Decapoda: Anomura: Kiwaidae)".Frontiers in Marine Science.9.doi:10.3389/fmars.2022.1051590.hdl:20.500.12613/10019.ISSN2296-7745.
  8. ^Macpherson E, Jones W, Segonzac M (2006)."A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacific-Antarctic Ridge"(PDF).Zoosystema.27(4): 709–723.
  9. ^Thurber AR, Jones WJ, Schnabel K (2011)."Dancing for food in the deep sea: bacterial farming by a new species of Yeti crab".PLOS ONE.6(11): e26243.Bibcode:2011PLoSO...626243T.doi:10.1371/journal.pone.0026243.PMC3227565.PMID22140426.
  10. ^abRoterman CN, Lee WK, Liu X, Lin R, Li X, Won YJ (2018)."A new yeti crab phylogeny: Vent origins with indications of regional extinction in the East Pacific".PLOS ONE.13(3): e0194696.Bibcode:2018PLoSO..1394696R.doi:10.1371/journal.pone.0194696.PMC5856415.PMID29547631.
  11. ^Amos J (2015-06-25)."'Hoff crab' gets formal scientific name ".BBC News.
  12. ^Rogers AD, Tyler PA, Connelly DP, Copley JT, James R, Larter RD, et al. (January 2012)."The discovery of new deep-sea hydrothermal vent communities in the southern ocean and implications for biogeography".PLOS Biology.10(1): e1001234.doi:10.1371/journal.pbio.1001234.PMC3250512.PMID22235194.
  13. ^Lee SH, Won YJ, Lee WK (2016)."A new species of yeti crab, genus Kiwa Macpherson, Jones and Segonzac, 2005 (Decapoda: Anomura: Kiwaidae), from a hydrothermal vent on the Australian-Antarctic Ridge".Journal of Crustacean Biology.36(2): 238–247.doi:10.1163/1937240x-00002418.
  14. ^Rebecca Morelle(December 28, 2011)."Deep-sea creatures at volcanic vent".BBC News.
  15. ^Roterman CN, Lee WK, Liu X, Lin R, Li X, Won YJ (2018)."A new yeti crab phylogeny: Vent origins with indications of regional extinction in the East Pacific".PLOS ONE.13(3): e0194696.Bibcode:2018PLoSO..1394696R.doi:10.1371/journal.pone.0194696.PMC5856415.PMID29547631.
  16. ^abRoterman CN, Copley JT, Linse KT, Tyler PA, Rogers AD (August 2013)."The biogeography of the yeti crabs (Kiwaidae) with notes on the phylogeny of the Chirostyloidea (Decapoda: Anomura)".Proceedings. Biological Sciences.280(1764): 20130718.doi:10.1098/rspb.2013.0718.PMC3712414.PMID23782878.
  17. ^Lee SH, Won YJ, Lee WK (2016)."A new species of yeti crab, genus Kiwa Macpherson, Jones and Segonzac, 2005 (Decapoda: Anomura: Kiwaidae), from a hydrothermal vent on the Australian-Antarctic Ridge".Journal of Crustacean Biology.36(2): 238–247.doi:10.1163/1937240x-00002418.
  18. ^Yong E (2011-12-02)."Yeti crab grows its own food".Nature.doi:10.1038/nature.2011.9537.ISSN1476-4687.
  19. ^Roterman CN (March 16, 2018)."A new yeti crab phylogeny: Vent origins with indications of regional extinction in the East Pacific".PLOS ONE.13(3): e0194696.Bibcode:2018PLoSO..1394696R.doi:10.1371/journal.pone.0194696.PMC5856415.PMID29547631.
  20. ^abScales H (2022).The Brilliant Abyss.Grove Press. pp. 80–81.
  21. ^abcdeAzofeifa-Solano JC, Pereira OS, Cowell EJ, Cordes EE, Levin LA, Goffredi SK, et al. (2022)."Sexual dimorphism in the methane seep-dwelling Costa Rican yeti crab Kiwa puravida (Decapoda: Anomura: Kiwaidae)".Frontiers in Marine Science.9.doi:10.3389/fmars.2022.1051590.hdl:20.500.12613/10019.ISSN2296-7745.
  22. ^Thatje S, Marsh L (2018)."From hot waters of polar seas: the mysterious life of the male yeti crab".Ecology.99(12): 2868–2870.Bibcode:2018Ecol...99.2868T.doi:10.1002/ecy.2468.ISSN0012-9658.JSTOR26627164.PMID30039867.
  23. ^Thatje S, Marsh L, Roterman CN, Mavrogordato MN, Linse K (2015-06-24)."Adaptations to Hydrothermal Vent Life in Kiwa tyleri, a New Species of Yeti Crab from the East Scotia Ridge, Antarctica".PLOS ONE.10(6): e0127621.Bibcode:2015PLoSO..1027621T.doi:10.1371/journal.pone.0127621.ISSN1932-6203.PMC4480985.PMID26107940.
  24. ^Marsh L, Copley JT, Tyler PA, Thatje S (2015-03-02). Webb T (ed.)."In hot and cold water: differential life-history traits are key to success in contrasting thermal deep-sea environments".Journal of Animal Ecology.84(4): 898–913.Bibcode:2015JAnEc..84..898M.doi:10.1111/1365-2656.12337.ISSN0021-8790.PMC4964920.PMID25732205.
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  • Data related toKiwaat Wikispecies
  • Media related toKiwaidaeat Wikimedia Commons
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