''Cinetorhynchus rigens'' 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 ...

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

in the family

Rhynchocinetidae The family Rhynchocinetidae are a group of small, reclusive red-and-white shrimp. This family typically has an upward-hinged foldable rostrum, hence its taxon name ''Rhynchocinetidae'', which means ''movable beak''; this gives these shrimps thei ...

. Common names include mechanical shrimp, Atlantic dancing shrimp, red night shrimp and red coral shrimp. It occurs in shallow water in the tropical Atlantic Ocean.

Description

Like other members of its family, ''Cinetorhynchus rigens'' has an upward-hinging, foldable rostrum. The body is robust, especially the cephalothorax, with a length of up to . The rostrum has three large and two small teeth dorsally and eight or nine teeth ventrally. The eyes are particularly noticeable, the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...

s being rounded and much larger than the eyestalks. The third abdominal segment is prominently humped. The first pair of walking legs are tipped with pincers and the other walking legs are more slender. The general colour of this shrimp is red and white, the rostrum being white with a patchwork of red blotches, the abdomen transversely striped with red and white and the legs banded in the same colours. At night, some of the white pigment is withdrawn into the chromatophores at the base of the legs and the colouring is more subdued. The eggs are yellow or orange; they may make the cephalothorax appear yellowish while they are maturing in the ovary, and the abdomen yellowish while they are being incubated.

Distribution and habitat

This species occurs in the tropical Atlantic Ocean. Its range extends from Portugal southwards to the equator and includes the Azores, Madeira, the Canaries and the Cape Verde Islands. It also occurs in the Gulf of Mexico, the Caribbean Sea, and from Bermuda southwards to Brazil. It was first described in 1936 by the Scottish marine biologist

Isabella Gordon Isabella Gordon OBE FZS FLS (18 May 1901 – 11 May 1988) was a Scottish marine biologist who specialised in carcinology and was an expert in crabs and sea spiders. She worked at the Natural History Museum and received an OBE in 1961. Ea ...

, the type locality being

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

. Further specimens were recorded from the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yonaguni ...

by the Japanese zoologist Takahiro Fujino in 1975, but on further examination, these are likely to be a different species and have been given the new species name of '' Cinetorhynchus erythrostictus''. ''C. rigens'' is usually found at depths of less than , in crevices and caves on rocky shores and coral reefs.

Ecology

The common name "dancing shrimp" comes from the habit this species has of constantly engaging in jerky movements. Its diet has not been studied, but it is likely to be a

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

, also consuming small invertebrates and organic particles. Examination of its faeces reveal sponge spicules, fragments of mollusc shells and algae. It is nocturnal, concealing itself during the day, sometimes in large numbers, in fissures among boulders. Its association with the

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

'' Diadema antillarum'' varies with the phase of the Moon, and it is often associated with

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 ...

s such as '' Telmatactis cricoides'', ''

Bartholomea annulata ''Bartholomea annulata'' is a species of sea anemone in the family Aiptasiidae, commonly known as the ringed anemone or corkscrew anemone. It is one of the most common anemones found on reefs in the Caribbean Sea. Description The ringed anemon ...

'', ''

Condylactis gigantea ''Condylactis gigantea'' is a tropical species of ball anemone that is found in shallow reefs and other shallow inshore areas in the Caribbean Sea – more specifically the West Indies – and the western Atlantic Ocean including southern F ...

'', and '' Lebrunia neglecta''. In Brazil, it has been found sharing crevices with the brown spiny lobster '' Panulirus echinatus''. The shrimp is preyed on 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,

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s and larger

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s. In the Caribbean, it forms part of the diet of the invasive lionfishes ''

Pterois volitans The red lionfish (''Pterois volitans'') is a venomous coral reef fish in the family Scorpaenidae, order Scorpaeniformes. It is mainly native to the Indo-Pacific region, but has become an invasive species in the Caribbean Sea, as well as along ...

'' and ''

Pterois miles ''Pterois miles'', the devil firefish or common lionfish, is a species of ray-finned fish native to the western Indo-Pacific region. It is frequently confused with its close relative, the red lionfish (''Pterois volitans''). The scientific name ...

''.

References

{{Taxonbar, from=Q4466831 Caridea Crustaceans of the Atlantic Ocean Animals described in 1936