''Neotrypaea californiensis'' (formerly ''Callianassa californiensis''), the Bay ghost shrimp, 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 ghost shrimp that lives on the Pacific coast of North America. It is a pale animal which grows to a length of . One claw is bigger than the other, especially in males, and the enlarged claw is thought to have a function in

mating In biology, mating is the pairing of either opposite- sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. ''Copulation'' is the union of the sex organs of two sexually reprod ...

. ''N. californiensis'' is a deposit feeder that lives in extensive burrow systems, and is responsible for high rates of bioturbation. It adversely affects oyster farms, and its numbers are controlled in some places by the application of pesticides. It carries out an important role in the ecosystem, and is used by fishermen as bait.

Description and life cycle

''Neotrypaea californiensis'' reaches a length of . The body is creamy white, with patches of pale colour (pink, yellow or orange) on the appendages, and a pink

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

. Adult ''N. californiensis'' have one claw larger than the other, and in the males, the "master claw" can make up as much as 25% of the animal's mass – compared to only 10% in females – with the minor claw making up around 3% of the total body mass in both sexes. The enlarged claw is equally likely to be on the right side or the left side. The male's larger claw is thought to be used in agonistic encounters or during

, and may be the result of

sexual selection Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ( ...

. Eggs are laid in spring or early summer, and the larvae hatch in summer, living as

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

. They settle to the sea floor again as post-larvae in the late summer and fall.

Taxonomy

''N. californiensis'' was originally described in 1854 by

James Dwight Dana James Dwight Dana FRS FRSE (February 12, 1813 – April 14, 1895) was an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcanic activity, and the origin and structure of continent ...

as a member of the genus ''

Callianassa ''Callianassa'' is a genus of mud shrimps, in the family Callianassidae. Three of the species in this genus ('' C. candida'', '' C. tyrrhena'' and '' C. whitei'') have been split off into a new genus, '' Pestarella'', while others such as '' C ...

'', giving the type locality as "California"; the material Dana studied was probably collected from San Francisco Bay or

Monterey Monterey (; es, Monterrey; Ohlone: ) is a city located in Monterey County on the southern edge of Monterey Bay on the U.S. state of California's Central Coast. Founded on June 3, 1770, it functioned as the capital of Alta California under bot ...

, but the original specimens have since been lost. In 1991, Raymond Manning and Darryl Felder transferred the three species in that genus that come from

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

and

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

into the new genus '' Neotrypaea''. ''N. californiensis'' is distinguished from the other two species of ''Neotrypaea'' by the lack of a

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ships * Ros ...

(which is present in '' Neotrypaea gigas'') and the acute and diverging tips of the

eyestalk In anatomy, an eyestalk (sometimes spelled eye stalk and also known as an ommatophore) is a protrusion that extends an eye away from the body, giving the eye a better field of view. It is a common feature in nature and frequently appears in fic ...

s (which are short, blunt and not diverging in '' Neotrypaea biffari'').

Ecology and human impact

Both ''Neotrypaea californiensis'' and the mud shrimp '' Upogebia pugettensis'' live in mudflats and

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...

y substrates in the intertidal zone of

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

in western North America. ''N. californiensis'' is found from Mutiny Bay,

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

to Punta Abreojos,

Mulegé Mulegé is a city in Mulegé Municipality, Baja California Sur, situated on the Gulf of California. Located on the Gulf of California, the population was 3,821 according to the Mexican census of 2010. History Indigenous peoples had lived in t ...

, Baja California Sur,

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. Its habitat is also used for the aquaculture of the

Pacific oyster The Pacific oyster, Japanese oyster, or Miyagi oyster (''Magallana gigas''), is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand. Etymology The genus ''Mag ...

, ''Crassostrea gigas''. Since the bioturbation carried out by ''N. californiensis'' and ''U. pugettensis'' reduces the productivity of the

oyster bed Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

s, they are considered pests. Their effects may, however, have knock-on effects across the entire

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

, and may buffer it from the hazards of nutrient enrichment and increase primary and secondary productivity by increasing the amount of dissolved inorganic

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

. The burrows made by ''N. californiensis'' have many branches, and a number of other animals live in them, including snapping shrimp of the genus '' Betaeus'', the copepod '' Clausidium vancouverense'', and the crab '' Scleroplax granulata''. The gut flora of ''N. californiensis'' includes a wide range of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

, comprising around 40%

Alphaproteobacteria Alphaproteobacteria is a class of bacteria in the phylum Pseudomonadota (formerly Proteobacteria). The Magnetococcales and Mariprofundales are considered basal or sister to the Alphaproteobacteria. The Alphaproteobacteria are highly diverse and ...

, 20% gram-positive bacteria, 20% Bacteroidota, and 5% of each of Gammaproteobacteria and

Campylobacterota Campylobacterota are a phylum of bacteria. All species of this phylum are Gram-negative. The Campylobacterota consist of few known genera, mainly the curved to spirilloid ''Wolinella'' spp., ''Helicobacter'' spp., and ''Campylobacter'' spp. Most ...

. Predators of ''N. californiensis'' include gray whales (''Eschrichtius robustus)'', bottom-dwelling

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 ...

, and

Dungeness crab The Dungeness crab (''Metacarcinus magister'') is a species of crab inhabiting eelgrass beds and water bottoms along the west coast of North America. It typically grows to across the carapace and is a popular seafood. Its common name comes f ...

s (''Metacarcinus magister''). ''N. californiensis'' has a negative impact on

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

production, and as a result, the insecticide

carbaryl Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin trademark ...

(1-napthyl N-methyl carbamate) is sprayed in some areas (including Willapa Bay,

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

) to reduce the population of ''N. californiensis''. The addition of shelly debris also reduces numbers of ''N. californiensis'' both by preventing the settlement of

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e, and through predation on the young ''N. californiensis'' by young Dungeness crabs in the shelly debris. ''N. californiensis'' is used as

fishing bait Fishing bait is any substance used to attract and catch fish, e.g. on a fishing hook. Bait items are both selected from and placed within the environment to achieve enhanced prey capture success. Traditionally, fishing baits are natural fish foo ...

, and is frequently transported alive between

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

s, prompting fears that existing population structure may be obliterated, and that it could introduce the castrating

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

isopod '' Ione cornuta'' outside its native range.

References

{{Authority control Thalassinidea Crustaceans of the eastern Pacific Ocean Crustaceans described in 1854