Thursday, 3 January 2013

What is Krill .....


Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name krill comes from the Norwegian word krill, meaning "young fry of fish", which is also often attributed to other species of fish.Many krill are filter feeders: their frontmost appendages, the thoracopods, form very fine combs with which they can filter out their food from the water. These filters can be very fine indeed in those species (such as Euphausia spp.) that feed primarily on phytoplankton, in particular on diatoms, which are unicellular algae. Krill are mostly omnivorous,although a few species are carnivorous, preying on small zooplankton and fish larvae.



Krill are an important element of the aquatic food chain. Krill convert the primary production of their prey into a form suitable for consumption by larger animals that cannot feed directly on the minuscule algae. Northern krill and some other species have a relatively small filtering basket and actively hunt copepods and larger zooplankton.

During the mating season, which varies by species and climate, the male deposits a sperm sack at the female's genital opening (named thelycum). The females can carry several thousand eggs in their ovary, which may then account for as much as one third of the animal's body mass. Krill can have multiple broods in one season, with interbrood intervals lasting on the order of days.Some high-latitude species of krill can live for more than six years (e.g., Euphausia superba); others, such as the mid-latitude species Euphausia pacifica, live for only two years. Subtropical or tropical species' longevity is still shorter, e.g., Nyctiphanes simplex, which usually lives for only six to eight months.





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