''Acartia'' is a genus of marine calanoid

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s. They are

epipelagic The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

estuarine 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 environm ...

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

ic found throughout the oceans of the world, primarily in temperate regions.

Classification

This genus contains the majority of species in the family Acartiidae: *'' Acartia adriatica'' Steuer, 1910 *'' Acartia amboinensis'' Carl, 1907 *'' Acartia arbruta'' Smith ''et al''., 2021 *'' Acartia australis'' Farran, 1936 *'' Acartia bacorehuisensis'' Zamora-Sánchez & Gómez-Aguirre, 1986 *'' Acartia bermudensis'' Esterly, 1911 *'' Acartia bifilosa'' (Giesbrecht, 1881) *''

Acartia bilobata ''Acartia'' is a genus of marine calanoid copepods. They are epipelagic, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority of species in the fa ...

'' Abraham, 1970 *'' Acartia bispinosa'' Carl, 1907 *'' Acartia bowmani'' Abraham, 1976 *'' Acartia cagayanensis'' Sakaguchi & Ueda, 2020 *'' Acartia californiensis'' Trinast, 1976 *'' Acartia centrura'' Giesbrecht, 1889 *'' Acartia chilkaensis'' Sewell, 1919 *''

Acartia clausi ''Acartia clausi'' is a species of marine copepod belonging to the family Acartiidae. This species was previously thought to have a worldwide distribution but recent research has restricted its range to coastal regions of the north-eastern Atlan ...

'' Giesbrecht, 1889 *'' Acartia danae'' Giesbrecht, 1889 *'' Acartia denticornis'' Brady, 1883 *'' Acartia discaudata'' (Giesbrecht, 1882) *''

Acartia dweepi ''Acartia'' is a genus of marine calanoid copepods. They are epipelagic, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority of species in the fa ...

'' Haridas & Madhupratap, 1978 *''

Acartia edentata ''Acartia'' is a genus of marine calanoid copepods. They are epipelagic, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority of species in the fa ...

'' Srinui, Ohtsuka & Metillo in Srinui, Ohtsuka, Metillo & Nishibori, 2019 *''

Acartia ensifera ''Acartia ensifera'' is a species of marine copepod belonging to the family Acartiidae. This is a slender copepod, around in length, with distinctively long caudal rami. It is found around the coasts of New Zealand. References ''Acartia ensif ...

'' Brady, 1899 *''

Acartia enzoi ''Acartia'' is a genus of marine calanoid copepods. They are epipelagic, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority of species in the fa ...

'' Crisafi, 1974 *'' Acartia erythraea'' Giesbrecht, 1889 *'' Acartia fancetti'' McKinnon, Kimmerer & Benzie, 1992 *'' Acartia floridana'' Davis, 1948 *'' Acartia forcipata'' I. C. Thompson & A. Scott ''in'' Thompson, Scott & Herdman, 1898 *'' Acartia forticrusa'' Soh, Moon, Park, Bun & Venmathi Maran, 2013 *'' Acartia fossae'' Gurney, 1927 *'' Acartia hongi'' Soh & Suh, 2000 *'' Acartia hudsonica'' Pinhey, 1926 *'' Acartia italica'' Steuer, 1910 *'' Acartia japonica'' Mori, 1940 *'' Acartia jilletti'' Bradford, 1976 *'' Acartia laxa'' Dana, 1852 *'' Acartia lefevreae'' Bradford, 1976 *'' Acartia levequei'' Grice, 1964 *'' Acartia lilljeborgii'' Giesbrecht, 1889 *'' Acartia limpida'' Dana, 1849 *'' Acartia longiremis'' (Lilljeborg, 1853) *'' Acartia longisetosa'' Brady, 1914 *'' Acartia macropus'' Cleve, 1900 *'' Acartia margalefi'' Alcaraz, 1976 *'' Acartia mediterranea'' Pesta, 1909 *'' Acartia mollicula'' Pavlova & Shmeleva, 2010 *'' Acartia mossi'' (Norman, 1878) *'' Acartia nadiensis'' Lee, S, Soh & W. Lee, 2019 *''

Acartia nana ''Acartia'' is a genus of marine calanoid copepods. They are epipelagic, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority of species in the fa ...

'' Brady, 1914 *'' Acartia negligens'' Dana, 1849 *'' Acartia ohtsukai'' Ueda & Bucklin, 2006 *'' Acartia omorii'' Bradford, 1976 *'' Acartia pacifica'' Steuer, 1915 *'' Acartia pietschmani'' Pesta, 1912 *'' Acartia plumosa'' T. Scott, 1894 *'' Acartia ponteloides'' (Kritchagin, 1873) *'' Acartia ransoni'' Vaissière, 1954 *'' Acartia remivagantis'' Oliveira, 1946 *'' Acartia sarojus'' Madhupratap & Haridas, 1994 *'' Acartia seshaiyai'' Subbaraju, 1968 *'' Acartia simplex'' G. O. Sars, 1905 *''

Acartia sinjiensis ''Acartia'' is a genus of marine Calanoida, calanoid copepods. They are epipelagic, Estuary, estuarine, zooplanktonic found throughout the oceans of the world, primarily in temperate regions. Classification This genus contains the majority o ...

'' Mori, 1940 *'' Acartia southwelli'' Sewell, 1914 *'' Acartia spinata'' Esterly, 1911 *'' Acartia spinicauda'' Giesbrecht, 1889 *'' Acartia steueri'' Smirnov, 1936 *'' Acartia teclae'' Bradford, 1976 *'' Acartia tonsa'' Dana, 1849 *'' Acartia tranteri'' Bradford, 1976 *'' Acartia tropica'' Ueda & Hiromi, 1987 *'' Acartia tsuensis'' ItoTak, 1956 *'' Acartia tumida'' Willey, 1920

Reproductive and life cycle

Female ''Acartia'' release eggs freely in the water. Nauplii hatch and undergo six distinct life stages to become copepodites and then undergo another six life stages to become fully mature copepods. Some species of ''Acartia'' are known to exhibit a

diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

, a resting period when the species is dormant, as a part of their life cycle. These species produce "resting eggs" when environmental conditions are unfavorable for the development and growth of nauplii. Individual females can switch between producing resting eggs and subitaneous eggs (eggs that hatch immediately) as environmental conditions change. Resting eggs accumulate in the sediment and hatch when conditions are optimal. Production of resting eggs is driven by water temperature variations. Some species (''A. hudsonica'') produce resting eggs when water temperatures rise above a certain threshold, while others (''A. tonsa, A. califoriensis'') have been observed to produce resting eggs when water temperatures fall below a certain threshold. Hatching and development of the species occur when the water cools (''A. hudonica'') or warms (''A. tonsa, A. califoriensis''). Additionally, ''A. califoriensis'' is known to be adapted to anomalous water temperature variations. Hatching is only followed by a period of steady water temperatures in the favorable range. This ensures that a generation of the species is not killed off by a momentary warming followed again by colder temperatures.

Diet

''Acartia'' primarily feed on

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

and are also known to consume

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

s, and their own eggs and nauplii. ''Acartia'' feeding patterns are asymptotic relative to the abundance of food. When food is widely abundant ''Acartia'' approach a maximum food intake. When there is less food available, feeding adjusts to rates that correlate with food availability.

Behaviour

In a study of ''A. tonsa'' in the

Narragansett Bay Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound covering , of which is in Rhode Island. The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago. S ...

the species was found to exhibit a diel feeding pattern, that is, a night feeding pattern. The diel feeding cycle was tested under a variety of light conditions and was found to be

endogenous Endogeny, in biology, refers to the property of originating or developing from within an organism, tissue, or cell. For example, ''endogenous substances'', and ''endogenous processes'' are those that originate within a living system (e.g. an ...

, not related to light availability, but persistent regardless of whether the copepods were subjected to light or dark. This feeding pattern is only known to be disrupted at extremely low food levels, implying that either "food limitation has over-ridden other factors governing diel feeding rhythms and induced continuous feeding, or that a synchronized population-wide feeding rhythm has given way to intermittent, asynchronous feeding among individuals." ''Acartia'' are also known to exhibit a

diel vertical migration Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The adjective "diel" ( IPA: , ) comes from , and refers to a 24-hour ...

pattern, swimming to depths during the day and rising to surface waters at night. The diel vertical migration of ''A. tonsa'' was seen to be effected by light exposure: when exposed to continuous light the copepods did not migrate to the surface. Both diel patterns are thought to be primarily adaptive behavior to avoid visual predators. The

mechanism Mechanism may refer to: *Mechanism (economics), a set of rules for a game designed to achieve a certain outcome **Mechanism design, the study of such mechanisms *Mechanism (engineering), rigid bodies connected by joints in order to accomplish a ...

of the diel vertical migration of ''Acartia'' has been explored further to solve the question of whether the copepods react to chemical signals indicating the presence of predators, physical stimuli resulting from the movement of predator fish in the water, or visual cues based on the changing light modified by a much larger predator. In a study of ''A. hudsonica'', the chemical response was ruled out. Additionally, other studies of ''Acartia'' (''A. longiremis, A. grani'' and ''A. discandata'') were found to have less

chemoreceptors A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance ( endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorece ...

and more mechanoreceptive sensory hairs than other marine copepods, suggesting that diel feeding and migration patterns in ''Arcatia'' are primarily driven by physical and visual cues.

References

{{Taxonbar, from=Q3808855 Calanoida Copepod genera Taxa named by James Dwight Dana