family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of marine
copepod
Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...
s. The family is cosmopolitan and occurs in all the oceans, including the Southern and Arctic Oceans. Euchaetidae are medium to large-sized copepods.
Genera
There are two genera with in total 114 species:
Ecology
''Euchaeta'' are mostly
epipelagic
The photic zone, 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 pro ...
whereas ''Paraeuchaeta'' are mostly
bathypelagic
The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of below the ocean surface. It lies between the mesopelagic above, and the abyssopelagic below. The bathypelag ...
. Where more than one species occurs, congeneric species (or life stages of a single species, as observed for ''Paraeuchaeta antarctica'') may partition the water column, whereas species representing different genera that occur at similar depths differ in dietary preferences.
''Paraeuchaeta'' can be important predators of fish larvae. Their mode of predation is " drift and wait". The dominant euchaetid in the
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...
is ''Paraeuchaeta antarctica''. It is a dominant predator there, and its
fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...
profile suggests that it mostly preys upon herbivorous calanid copepods. In the
Weddell Sea
The Weddell Sea is part of the Southern Ocean and contains the Weddell Gyre. Its land boundaries are defined by the bay formed from the coasts of Coats Land and the Antarctic Peninsula. The easternmost point is Cape Norvegia at Princess Mar ...
, it contributes as much as 11–18% to total mesozooplankton biomass.
Life cycle
''Paraeuchaeta antarctica'' has a one-year life-cycle around the
Kerguelen Islands
The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic constituting one of the two exposed parts of the Kerguelen Plateau, a l ...