Acanthonyx dentatus, the toothed decorator crab, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of crab

Crab

True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...

 in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Inachidae

Inachidae

Inachidae is a family of crabs, containing 39 genera:*Achaeopsis Stimpson, 1857*Achaeus Leach, 1815*Anisonotus A. Milne-Edwards, 1879*Anomalothir Miers, 1879*Bothromaia Williams & Moffitt, 1991...

.

Distribution

The toothed decorator crab is known around the southern African coast from Cape Columbine

Cape Columbine

Cape Columbine is well known for its lighthouse, the last manned lighthouse built on the South African coast. . The Cape Columbine Lighthouse was commissioned on October 1, 1936...

 to Richards Bay subtidally to 43 metres (141.1 ft). It is also known from the Red Sea.

Description

The toothed decorator crab may grow to 40 millimetres (1.6 in) across. It is usually a well camouflaged crab, decorating its carapace with hydroid

Hydroid

-Marine biology:Hydroids are a life stage for most animals of class Hydrozoa, small predators related to jellyfish.-Botany:In mosses, hydroids form the innermost layer of the stem of long, colourless, thin walled cells of small diameter.The cells are dead and lack protoplasm.They function as water...

s and seaweed

Seaweed

Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...

s. Its carapace is teardrop-shaped with two sharp spines projecting forwards between its eyes. There are two marginal spines on its carapace. It has stubby legs. It is a vivid pink-red to a dull brown in colour.

Ecology

Vividly coloured when recently moulted, these animals are commonly found taking refuge among groups of striped anemones. The crabs use the anemones' habit of shooting sticky defensive threads through their body walls for their own defence.