Ranina ranina
Introduction Ranina ranina by Kawahara Keiga, 1823 - 1829.Siebold Collection. '''''Ranina ranina''''', also known as the '''Huỳnh Đế crab''', '''(red) frog crab''' or '''spanner crab''', is a species of crab found throughout tropical and subtropical habitats. It is often fished for its meat, and is the only known species in its genus.
Description It may grow up to  long, and may weigh up to . The carapace is wider at the front, reddish brown in color, with ten white spots. ''Ranina ranina'' is mainly nocturnal, and remains buried in the sand during the day. ''Ranina ranina'' is easily distinguished from other crab species in its habitat due to its red carapace and elongated midsection.
Distribution and ecology Spanner crabs inhabit coastal waters along the east coast of Australia, from Yeppoon in Queensland to the North coast of New South Wales. There is also a population to the north of Perth in Western Australia. ''Ranina ranina'' is abundant in the coastal waters of south-western Mindanao, Philippines. These crabs are also found in the eastern coast of Africa, across the Indian Ocean to Indonesia, Japan and Hawaii and Vietnam. ''Ranina ranina'' inhabits depths of  on sandy-smooth substrata in which they bury themselves from where they attack small bottom-dwelling fish. When waiting for prey, ''Ranina ranina'' will cover itself with sand, but leave its eye and mouthparts sticking out to help detect its food. Offshore areas within this range in a subtropical or tropical environment serves as a habitat for ''Ranina ranina'', but they must have ample sand for ''Ranina ranina'' to flourish, as covering themselves in sand is instrumental in their method of catching prey. The Ranina Ranina crab is a popular species of crab that gets fished, in Australia, 96% of the female crab doesn’t get fished. In one location during spawning season, the decrease in females being hunted doesn’t apply. Meaning that the specific area of Tallows Beach is the focus of spawning migration.
Fishery The species is commercially exploited over much of its range, but the largest fishery is in Australia, where the annual commercial catch an estimated at . In Queensland, only adults above  carapace length may be landed. In the Philippines in 2008, prices for ''Ranina ranina'' were around 200–300 pesos per kilogram. ''Ranina ranina'' populations have been surveyed to avoid overfishing and are currently stable.Although ''Ranina ranina'' is a target of commercial fishing operations, little is known about the species' biology, population dynamics and ecology. Attempts have been made to grow ''Ranina ranina'' in captivity, but have so far been met with little success.
Culinary use ''Ranina ranina'' is a regional specialty in some regions of the Philippines where it is known as ''curacha''. It is generally eaten steamed as ''halabos'', or cooked in coconut milk as ''ginataan''. A notable variant of the latter is the ''curacha Alavar'' of Zamboanga City.In Vietnam the species is named as "Huỳnh Đế crab", literally means "emperor crab". The names refer to the fact that ''R. ranina'' is one of the favorite high-ranked cuisine of historical Vietnamese monarchs. It is the delicacy harvested in the provinces Bình Định and Quảng Ngãi, and is hailed "monarch of all the crab".
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