''Libinia ferreirae'' 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 tropical spider crab in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Epialtidae Epialtidae is a family of crabs, containing the subfamilies: * Epialtinae MacLeay, 1838 * Pisinae Pisinae is a subfamily of crabs in the family Epialtidae, comprising the following genera: * '' Acanthophrys'' A. Milne-Edwards, 1865 * '' Ana ...

. It is found on the

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

in shallow waters off the Atlantic coast of South America.

Description

Like other spider crabs, ''Libinia ferreirae'' has a roughly circular spiny

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 ...

that extends forwards into a rostrum between the two, stalked eyes. It has five pairs of walking limbs.

Distribution

''Libinia ferreirae'' is found off the Atlantic coast of South America in the intertidal zone and at depths down to about . The range extends from

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

and the

Guianas The Guianas, sometimes called by the Spanish loan-word ''Guayanas'' (''Las Guayanas''), is a region in north-eastern South America which includes the following three territories: * French Guiana, an overseas department and region of France * ...

, through parts of

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

Biology

The larvae of ''Libinia ferreirae'' are planktonic and have one prezoeal stage, two zoeal stages and one megalopa stage. The carapace of the zoea has one short rostral and one curved dorsal spine and some of the abdominal segments have spiny projections. The post-larval megalopa has a downturned rostrum, a carapace with various protuberances and four pairs of abdominal appendages.

Ecology

''Libinia ferreirae'' is often found in association with the jellyfish, '' Lychnorhiza lucerna''. Juvenile crabs are found living within the bell, on the oral arms or clinging to the exterior, even on jellies that have been stranded on the shore. The crabs are mostly less than in diameter and probably colonized the jellyfish when they were larvae. The number of jellyfish acting as host is low but increases with the size of the jellyfish and the inhabited ones mostly house a single crab. The crab may be immune to or able to tolerate the jellyfish stings. It is thought that the crab benefits from using the jellyfish as a nursery because free-living, young crabs are eaten by

predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

fish. Other benefits of this arrangement to the crab are a potential increase in food supply and transport to new locations. There do not seem to be any benefits to the jellyfish and the arrangement may be deleterious to it if the crab nibbles its interior tissues, as happens in some other crab/jellyfish relationships. At some stage the crab emerges from the bell and falls to the sea bed. Adult ''Libinia ferreirae'' often have faunal epibionts growing on their carapace. These include

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, polychaete worms,

sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

ns and hydroids. The most common species growing on the carapace was the sea anemone, ''

Calliactis tricolor ''Calliactis tricolor'', the tricolor anemone or hitchhiking anemone, is a species of sea anemone in the family Hormathiidae. It occurs in the Caribbean Sea and the Gulf of Mexico. It can be found attached to rocks but is often attached to a livi ...

'', which seems to be used by the crabs as

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

. Bryozoans colonised the legs as well as the carapace.

References

{{Taxonbar, from=Q13400675 Majoidea Crustaceans of the Atlantic Ocean Crustaceans described in 1871