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Krill are mostly omnivorous, [43] although a few species are carnivorous, preying on small zooplankton and fish larvae. [44] Krill are an important element of the aquatic food chain. Krill convert the primary production of their prey into
Metanauplius is an early larval stage of some crustaceans such as krill. It follows the nauplius stage. In sac-spawning krill, [ Note 1 ] there is an intermediary phase called pseudometanauplius , a newly hatched form distinguished from older metanauplii by its extremely short abdomen .
A shed carapace of a lady crab, part of the hard exoskeleton Body structure of a typical crustacean – krill. The body of a crustacean is composed of segments, which are grouped into three regions: the cephalon or head, [5] the pereon or thorax, [6] and the pleon or abdomen. [7]
Female krill lay over 10,000 eggs, sometimes seasonally, resulting in large populations. The Thysanoessa larvae are slender and their carapace is short in early stages. [ 5 ] As the body expands, the cephalothorax becomes transparent.
The larvae of remipedes are lecithotrophic, consuming egg yolk rather than using external food sources. This characteristic, which is shared with malacostracan groups such as the Decapoda and Euphausiacea (krill) has been used to suggest a link between Remipedia and Malacostraca. [8]
Krill and copepods are not as widely fished, but may be the animals with the greatest biomass on the planet, and form a vital part of the food chain. The scientific study of crustaceans is known as carcinology (alternatively, malacostracology , crustaceology or crustalogy ), and a scientist who works in carcinology is a carcinologist .
Unlike most other krill species, the eggs of E. crystallorophias are neutrally buoyant, meaning they do not sink, and the hatchling larvae do not have to swim back to the more productive, shallower waters; however, since this means both life stages inhabit the same depths, how the larvae avoid being eaten by the adults is not known. [6]
The change in the environment of the second stage larvae from the open water to the body of its host initiates their development into third stage larvae. [5] The krill infected by third stage larvae are then ingested by common predators, such as squid and fish, specifically teleosts, who then become paratenic hosts. [3]