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Metanauplius is an early larval stage of some
Metanauplius is an early larval stage of some crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s such as 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
Norwegian, Norwayan, or Norsk may refer to:
*Something of, from, or related to Norway, a country in n ...
. It follows the nauplius stage.
In sac-spawning krill, there is an intermediary phase called pseudometanauplius, a newly hatched form distinguished from older metanauplii by its extremely short abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
. In some species, this form is not considered a separate developmental stage as it develops into a metanauplius without molting
In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
; in other species such as ''Nyctiphanes couchii
''Nyctiphanes'' is a genus of krill, comprising four species with an anti-tropical distribution. Based on molecular phylogenetic analyses of the cytochrome oxidase gene and 16S ribosomal DNA, ''Nyctiphanes'' is believed to have evolved during ...
'', it can be separated from the metanauplius stage by the molt of a very thin cuticle soon after hatching.
Broadcast-spawning species of krill do not have a pseudometanauplius stage. They generally hatch in the nauplius 1 stage, but recently have been discovered to hatch sometimes as metanauplius or even as calyptopis stages.
See also
*Crustacean larvae
Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...
Footnotes
References
{{reflist, 2 Crustaceans Krill Larvae