''Cardisoma armatum'' 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 terrestrial crab.

Names

It is sometimes referred to as the (African) rainbow crab, (Nigerian) moon crab, or patriot crab. Adults are sometimes labelled as "soapdish" crabs in the pet industry. This name derives from their aggressive nature as adults and when being shipped to pet stores, they are often packed in

soap dish A soap dish is a shallow, open container or platform where a bar of soap may be placed to dry after use. Soap dishes are usually located in or near a sink, shower, or bathtub. Most soap dishes are made from waterproof materials such as plastic, ...

es to prevent them from killing each other. The names moon crab and soapdish crab are sometimes applied to other similar crab species, leading to frequent confusion with other colourful crabs such as the three remaining species of ''

Cardisoma ''Cardisoma'' is a genus of large land crabs. Three species formerly placed in this genus are now placed in '' Discoplax''. The four species that remain in ''Cardisoma'' are found in warm coastal regions where they live in burrows. Young individu ...

'', ''

Gecarcinus ruricola ''Gecarcinus ruricola'' is a species of terrestrial crab. It is the most terrestrial of the Caribbean land crabs, and is found from western Cuba across the Antilles as far east as Barbados. Common names for ''G. ruricola'' include the purple land ...

'', and '' G. quadratus'' (all except '' C. carnifex'' from the

Americas The Americas, which are sometimes collectively called America, are a landmass comprising the totality of North and South America. The Americas make up most of the land in Earth's Western Hemisphere and comprise the New World. Along with th ...

Distribution

''C. armatum'' originates from coastal regions of western Africa, but it also occurs inland along some deltas (e.g. the Volta River delta), and on islands such as

Cape Verde , national_anthem = () , official_languages = Portuguese , national_languages = Cape Verdean Creole , capital = Praia , coordinates = , largest_city = capital , demonym ...

Description

When young, these crabs typically have a blueish/violet

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 ...

, red–colored legs, and whitish claws. This coloration usually fades as the animal grows older. They can reach a carapace size of 20 cm across, although captive individuals rarely reach this size.

Ecology and life cycle

Their diet consists mainly of

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

, vegetation, and

carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...

. They are known to be cannibalistic, and consume smaller crabs, small

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s and

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

, and

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

s if they can catch them. While juvenile and adult crabs spend most of their time on dry land, the females must return to the ocean to release their eggs. The eggs hatch into microscopic larvae, and later on develop into young crabs. If the young do not make landfall by the time they are fully developed, they will drown. This land crab cannot remain submerged for long periods.

References

* Bright, D., & C. Hogue. 1972. ''A synopsis of burrowing land crabs of the World and list of their arthropod symbionts and burrow associates.'' Contributions in Science. No. 220
Available online (PDF)
* * {{Taxonbar, from=Q1423185 Grapsoidea Terrestrial crustaceans Crustaceans described in 1851 Fauna of Cape Verde