''Ranina ranina'', also known as the Huỳnh Đế crab, (red) frog crab or spanner crab, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of crab found throughout

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and subtropical

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. It is often fished for its meat, and is the only known species in its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...

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.Juliana C. Baylon & Oliver D. Tito (2012) “Natural diet and feeding habits of the red frog crab (''Ranina ranina'') from southwestern Mindanao, Philippines” Philip. Agric. Scientist Vol. 95 No. 4, 391–398. ''Ranina ranina'' inhabits depths of on sandy-smooth substrata in which they bury themselves from where they attack small bottom-dwelling fish.Sydney Fish Market, “Species information: Spanner Crab” (2013) www.sydneyfishmarket.com 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 Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

, but the largest fishery is in Australia, where the annual commercial catch an estimated at .Queensland Fisheries (2010) “Stock Status of Queensland's Fisheries Resources 2009-10” Queensland Australia: Queensland Department of Employment, Economic Development and Innovation. 65 In

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

, only adults above carapace length may be landed. In the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

in 2008, prices for ''Ranina ranina'' were around 200–300

pesos The peso is the monetary unit of several countries in the Americas, and the Philippines. Originating in the Spanish Empire, the word translates to "weight". In most countries the peso uses the same sign, "$", as many currencies named "dollar" ...

per kilogram. ''Ranina ranina'' populations have been surveyed to avoid overfishing and are currently stable.J. McGilvray, I. Brown, E. Jebreen & D. Smallwood (2006) Fisheries Long Term Monitoring Program Summary of spanner crab (''Ranina ranina'') survey results: 2000-2005. Department of Primary Industries and Fisheries, Queensland, QI06095, Brisbane, Australia. 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 ''Ginataan'' (pronounced: ), alternatively spelled ''guinataan'', is a Filipino term which refers to food cooked with ''gatâ'' ( coconut milk). Literally translated, ''ginataan'' means "done with coconut milk". Due to the general nature of the ...

''. A notable variant of the latter is the '' curacha Alavar'' of

Zamboanga City Zamboanga City, officially the City of Zamboanga (Chavacano and es, Ciudad de Zamboanga, Tausūg: ''Dāira sin Sambuangan'', fil, Lungsod ng Zamboanga, ceb, Dakbayan sa Zamboanga), is a city in the Zamboanga Peninsula region of the Philipp ...

. 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 Quảng Ngãi () is a city in central Vietnam. It serves as the capital city of Quảng Ngãi Province. Quảng Ngãi City borders Tư Nghĩa District to the south and west, Sơn Tịnh District to the northwest and Bình Sơn District to the ...

, and is hailed "monarch of all the crab".

References

{{DEFAULTSORT:crab, spanner spanner crab Marine fauna of Eastern Australia Edible crustaceans Commercial crustaceans spanner crab spanner crab