''Periclimenes rathbunae'' 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 shrimp in the family

Palaemonidae Palaemonidae is a family of shrimp in the order Decapoda. Many species are carnivores that eat small invertebrates, and can be found in any aquatic habitat except the deep sea. One significant genus is ''Macrobrachium'', which contains commerc ...

, also known as the sun anemone shrimp. It is found in the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

, the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

and

the Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the Atlantic Ocean, North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to ...

. It was first described by American biologist Waldo LaSalle Schmitt in 1924 and named in honor of American zoologist

Mary J. Rathbun Mary Jane Rathbun (June 11, 1860 – April 4, 1943) was an American zoologist who specialized in crustaceans. She worked at the Smithsonian Institution from 1884 until her death. She described more than a thousand new species and subspecies and ...

. This shrimp is usually found living in association with the sea anemone ''

Stichodactyla helianthus ''Stichodactyla helianthus'', commonly known as sun anemone, is a sea anemone of the family Stichodactylidae. ''Helianthus'' stems from the Greek words ἡλιος (meaning sun), and ἀνθος, meaning flower. ''S. helianthus'' is a large, gr ...

'' or occasionally with ''

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 ...

''.

Description

This shrimp grows to a length of about . In general it is clear and colourless, but there are many small orange and white spots on the appendages that sometimes lie close together and form bands. 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 clear with a partial dorsal saddle of orange and white spots, and the

somite The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide in ...

s have clear dorsal saddles with orange edges, outlined faintly in white. The sea anemone with which this shrimp usually associates, ''

'', is generally green or olive, and the associated shrimp may have a slight greenish tinge; it may appear rather more intense green because of light transmitted through its body. If its usual host is not available, ''P. rathbunae'' may associate with the giant Caribbean sea anemone (''

''). The tentacles of this anemone have a wide range of colouring including white, pink, orange, pale blue and tan, usually with paler tips, and the shrimps associated with it exhibit a limited ability to match their host, with a greater degree of white spotting and with no greenish tinge.

Distribution and habitat

''P. rathbunae'' is native to the Bahamas, Florida, the Caribbean Sea and the Gulf of Mexico. It is found at depths between about .

Ecology

''P. rathbunae'' is often associated with the sea anemone ''Stichodactyla helianthus'' in a

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

arrangement. In Tobago, most sea anemones of this species have associated shrimps, with an average of 3.4 shrimps per occupied anemone, and a maximum of eleven shrimps. The shrimps live among the anemone's tentacles and seem immune to attack by the host's

nematocyst A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...

s. It has been found that if a shrimp is separated from an anemone for as little as twenty-four hours, it loses its immunity. A period of up to five hours is then required to re-establish the immunity, during which time cautious contact is made by the shrimp. The mechanism involved in the immunity may involve the coating of the shrimp with anemone mucus, after which it becomes chemically camouflaged.

References

{{Taxonbar, from=Q4470458 Palaemonidae Crustaceans described in 1924