You may know the Hermit crabs, the fiddler crabs, the King crab or the spider crabs, but have you heard of the Buddhist crab? With a body size of about 0.5 cm, the Buddhist crab, ๐๐ฎ๐ฆ๐ต๐ฉ๐บ๐ฑ๐ฐ๐ค๐ฐ๐ฆ๐ญ๐ช๐ด ๐ค๐ฆ๐ณ๐ข๐ต๐ฐ๐ฑ๐ฉ๐ฐ๐ณ๐ข (Koelbel, 1897) is one of the smallest native crab species found in Hong Kong; where the species was actually described 125 years ago. Its small size, however, did not prevent it from spreading widely as the species is also found in Japan, Indonesia, Vietnam and Taiwan. Like other crabs, they live in brackish waters such as in sandy beachesand mudflats. But due to their grayish brown colors, it may be hard to observe them. The common name of this species as Buddhist crab poorly reflects its diet, as far from being vegetarian, they will instead scavenge on dead animals like small fish and mollusks that are found on the sand surface.
The nickname of "Buddhist" refers to the waving display observed in this species that some have associated with a โworship to the gods''. First, an individual folds both chelipeds (claws) in front of their cheek, unfolds it laterally, raises upwards, lower frontally and re-fold it again. The short moment in which they re-fold their chelipeds is also similar to the form of ritual suicide (Seppuku) that originated in Japan ancient samurai warriors. Hence, they are also called โincision crabโ in chinese.
So what is the purpose of keeping this unusual posture? Unfortunately, the exact function remains unknown; however, we can still infer it based on other species behaviors such those observed in Fiddler crabs and Ghost crabs, which use similar postures to defend their territory and mating.
๐๐ฎ๐ฆ๐ต๐ฉ๐บ๐ฑ๐ฐ๐ค๐ฐ๐ฆ๐ญ๐ช๐ด ๐ค๐ฆ๐ณ๐ข๐ต๐ฐ๐ฑ๐ฉ๐ฐ๐ณ๐ข was once believed to be the only species within the genus ๐๐ฎ๐ฆ๐ต๐ฉ๐บ๐ฑ๐ฐ๐ค๐ฐ๐ฆ๐ญ๐ช๐ด (try to pronounce it) but this is not the case anymore. Both ๐๐ฎ๐ฆ๐ต๐ฉ๐บ๐ฑ๐ฐ๐ค๐ฐ๐ฆ๐ญ๐ช๐ด ๐ฌ๐ฐ๐ฆ๐ญ๐ฃ๐ฆ๐ญ๐ช and ๐.๐ฐ๐ฅ๐ฐ๐ฏ๐ต๐ฐ๐ฅ๐ข๐ค๐ต๐บ๐ญ๐ถ๐ด were described in 1990 while ๐.๐ค๐ฉ๐ฐ๐ณ๐ฆ๐ถ๐ต๐ฆ๐ด is the latest described species from Japan in 1995 (and previously confused as ๐.๐ค๐ฆ๐ณ๐ข๐ต๐ฐ๐ฑ๐ฉ๐ฐ๐ณ๐ข). In this latest species, its scientific name is quite informative as the epithet โ๐ค๐ฉ๐ฐ๐ณ๐ฆ๐ถ๐ต๐ฆ๐ดโ in Greek means โdancerโ. Can you guess why? When they raise up their arms, their second pair of legs are also lifted off the ground! Just like we use both hands and legs to dance.
They may not look very different to your run-of-the-mill crabs, but their signature movements will surely let you recognize them right away. If you are lucky enough to find one in Hong Kong, be sure to check out their peculiar dance!
Text: Phoebe Leung
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