Acartia tonsa is a species of marine copepod in the family Acartiidae.
Distribution
Acartia tonsa is a species of
calanoid copepod that can be found in a large portion of the world's
estuary and areas of
upwelling where food concentrations are high.
Like many plankton common to estuarine , they can live in a wide range of temperatures and salinity.
Characteristics
Acartia tonsa is translucent,
and is usually between about in length in females, and from about in males.
It "can be differentiated from closely related species by their long first antennae (at least half the length of their bodies) and biramous (branched) second antennae, as well as the presence of a joint between their fifth and sixth body segments".
Ecology and behavior
In estuaries and coastal waters which are warm throughout the year,
A. tonsa is found year-round. In cooler climates including the North Atlantic, it is frequently the dominant
zooplankton in the spring and summer.
Acartia tonsa produces eggs in the winter in colder geographic regions. The eggs hatch when temperatures exceed .
They are an important food source for many commercial fish species.
Feeding
A. tonsa nauplii and adults feed on phytoplankton as well as planktonic
and
.
It acts as a suspension feeder when feeding on phytoplankton. When feeding on motile prey it acts as an
Ambush predator; it stays nearly motionless in the water, detects movement of its prey, and then jumps toward the prey. Moderate amounts of turbulence improve rates of ambush feedings.
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