''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 ...

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

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 The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

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 extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Description

It may grow up to long, and may weigh up to . The

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

is wider at the front, reddish brown in color, with ten white spots. ''Ranina ranina'' is mainly

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

, 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 of s ...

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 , established_ ...

, only adults above

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 The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...

. ''Ranina ranina'' populations have been surveyed to avoid

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

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 ''Curacha'', also known as "spanner crab" or "red frog crab", is a local Chavacano name given to ''Ranina ranina'', commonly found in the waters of Sulu province and Zamboanga and Bataan province. It is a large crab with a red color, which stays ...

''. It is generally eaten steamed as ''

halabos ''Halabós'' is a Filipino cooking process consisting of fresh shrimp, crab, or other crustaceans cooked in water and salt. Modern versions of the dish commonly add spices and use carbonated lemon drinks instead of water for a sweeter sauce. ...

'', 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 t ...

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

curacha Alavar ''Curacha Alavar'', sometimes referred to as ''curacha con salsa Alavar'' ("Curacha with Alavar sauce") in Chavacano a Spanish-based creole language, is a Filipino dish made from spanner crabs (''curacha''), garlic, ginger, salt, and Alavar sauc ...

'' of

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

. 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 n ...

, 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