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The Galatheid Crab (Shinkaia crosnieri) is a small, deep-sea crustacean found in both Endless Ocean and Endless Ocean: Blue World.

Though it is called a "crab", it is actually more closely related to lobsters and shrimp. It regularly makes its home around the bases of hydrothermal vents in the deepest parts of the ocean.

Encyclopedia Description

Endless Ocean

"These animals have hard, elliptical shells and one pair of legs that ends in claws. They are generally white, with short, hard hairs on the back and belly. They can be seen year-round near thermal vents in the Abyss.

Though they are related to shrimps, the rear of their bodies is bent under toward the pelvic region, giving them a crab-like appearance at first glance. They also appear to have only four sets of legs when they actually have five. The fifth set, however, is very small and difficult to see.

The hydrothermal vents where this species lives are also home to bacteria that feed off matter emitted from them. These bacteria will often attach themselves to galatheid crabs, who then snack on them. These crabs aren't especially heat resistant, but the water around the vents is only slightly warm, and so habitable."

Endless Ocean: Blue World

"This creature is white, with hair on its belly and legs.

While it is a member of the lobster family, it looks more like a crab because its tail is bent towards its stomach.

It seems to have only four pairs of legs, but it actually has five like all lobsters; the last pair are almost too small to be visible."

[Growing Their Own Food]

"This species lives near hydrothermal vents which feed bacteria with the minerals they release. Galatheid crabs let the bacteria live in the hair on their bodies, then feed on them once they have grown.

As the water around the vents is not very hot, the crabs do not need to be resistant to heat. Also, they do not turn red when boiled."

Location

Endless Ocean

Small groups of two or three galatheid crabs can be seen in the Abyss, under zoom-mode glows by the hydrothermal vents.

Endless Ocean: Blue World

These can be seen under zoom-mode glows in the Chimney Forest of the Southern Crevasse of the Zahhab Region Depths.

Behavior

These are found under glows, by themselves, sometimes seen with deep-sea blind shrimp or, in Endless Ocean 2, with Venus' flower baskets.

Notes

  • In Endless Ocean, these are almost always found during the night, as most of the time their zoom-mode glows happen to be placed too close to the hydrothermal vents to be focused on before the hot water interrupts. On some rare occasions, the glows can be found on the boundary between the hydrothermal vents region and the sand, which lets the player find them during the day.

Real-Life Information

  • Both games accurately report that the galatheid crab has short hairs on its legs and body[1]. The scientific word for bristly or hairlike animal parts like these is "setae", singular "seta", and the galatheid crab uses the setae on its belly as a site to essentially "farm" bacteria that it then feeds on[2].
    • This "farming" behavior is referred to by researchers as "cultivation mutualism", where the bacteria get to live on the crab and the crab gets to eat the bacteria[3]. ("Mutualism" is the kind of symbiosis wherein both creatures benefit from each others' presences.)
    • A little more than 85% of the bacteria the galatheid crab eats are a kind called "epsilonproteobacteria"; the next-highest percentage of bacteria come from a class called "gammaproteobacteria"[4].
    • The bacteria themselves live by feeding off of the chemicals that hydrothermal vents give off, something called "chemosynthesis"[5].
  • While both games are correct in reporting and showing that the galatheid crab largely lives around the bases of hydrothermal vents, it has also been discovered to live at sites called "cold seeps" or just "seeps", where gases bubble up from beneath the seabed[6].
    • The cold-seep and hydrothermal-vent populations of galatheid crab are distinct from each other, though not distinct enough to be considered entirely separate species[6]. Different parts of their genetic code work in order to adapt them to their surrounding environment, which makes their bodies operate uniquely from each other, but they are still the same animal[7].
      • This genetic flexibility is something that researchers are studying to see how a changing environment can affect an animal's genes[8].
    • Though these sites are called "cold seeps", they are really just close to the temperature of the surrounding environment (in a sharp contrast to the boiling water of hydrothermal vents)[9].
  • This species was first described in the year 1998, making it a relatively recent discovery[10]. It was named by biologists Keiji Baba and Austin B. Williams[11].

Gallery

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References

  1. "The first deep-sea hydrothermal animal reported from Taiwan : Shinkaia crosnieri Baba and Williams, 1998 (Crustacea:Decapoda:Galatheidae)"; T. Chan, Ding-An Lee, and Chao-Shing Lee
  2. "Epibiotic association between filamentous bacteria and the vent-associated galatheid crab, Shinkaia crosnieri (Decapoda: Anomura)"; Shinji Tsuchida, Yohey Suzuki, Yoshihiro Fujiwara, Masaru Kawato, Katsuyuki Uematsu, Toshiro Yamanaka, Chitoshi Mizota, and Hiroyuki Yamamoto
  3. "Cultivation mutualism between a deep-sea vent galatheid crab and its chemosynthetic epibionts"; Tomo-o Watsuji. Remi Tsubaki, Chong Chen, Yukiko Nagai, Satoshi Nakagawa, Masahiro Yamamoto, Daisuke Nishiura, Takashi Toyofuku, and Ken Takai
  4. "Bacterial communities associated with Shinkaia crosnieri from the Iheya North, Okinawa Trough: Microbial diversity and metabolic potentials"; JianZhangl, Zhi-gang Zeng, Shuai Chen, and Li Sun
  5. "Molecular evidence of digestion and absorption of epibiotic bacterial community by deep-sea crab Shinkaia crosnieri"; Tomo-o Watsuji, Asami Yamamoto, Kaori Motoki, Kenji Ueda, Emi Hada, Yoshihiro Takaki, Shinsuke Kawagucci, and Ken Takai
  6. 6.0 6.1 "Connectivity of the squat lobsters Shinkaia crosnieri (Crustacea: Decapoda: Galatheidae) between cold seep and hydrothermal vent habitats"; Chien-Hui Yang, Shinji Tsuchida, Katsunori Fijikura Yoshihiro Fujiwara, Masaru Kawato, and Tin Yam Chan
  7. "Population Genetic Structure and Gene Expression Plasticity of the Deep-Sea Vent and Seep Squat Lobster Shinkaia crosnieri"; Yao Xiao, Ting Xu, Jin Sun, Yan Wang, Wai Chuen Wong, Yick Hang Kwan, Chong Chen, Jian-Wen Qiu, and Pei-Yuan Qian
  8. "Transcriptomic analysis reveals insights into deep-sea adaptations of the dominant species, Shinkaia crosnieri (Crustacea: Decapoda: Anomura), inhabiting both hydrothermal vents and cold seeps"; Jiao Cheng, Min Hui, and Zhongli Sha
  9. "New Eocene Hydrocarbon Seep Decapod Crustacean (Anomura: Galatheidae: Shinkaiinae) and Its Paleobiology"; Carrie E. Schweitzer and Rodney M. Feldmann
  10. World Register of Marine Species
  11. NCBI
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