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(invertebrate zoology)
A primitive larval stage of certain decapod crustaceans characterized by seven pairs of appendages; follows the nauplius stage.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the larval stage of crustaceans that follows the nauplius. Crayfish in the metanauplius stage have their first three pairs of appendages, which perform the function of loco-motion. These appendages are converted into antennules and antennae, which perform a tactile function, and into mandibles, which serve to grind food. The metanauplius moves by means of new appendages. In Ostracoda a rudimentary shell appears in the metanauplius stage.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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Lawrence, Canada (Moriyasu and Lanteigne, 1998) Stage # Morphometric development stage 1 prefuniculus 2 funiculus 3 cleavage and blastula 4 gastrula 5 lateral ectodermal band 6 prenauplius 7 nauplius 8 maxilliped formation 9 metanauplius 10 late metanauplius 11 eye pigment formation 12 chromataphore formation 13 reduced yolk 14 prehatching
This interval prior to capture and ingestion of the first metanauplius tended to be longer than the pauses between subsequent captures.
Because of complications in the use of untethered larvae, compounded by limitations of both field of view and of field of focus, only one sequence was recorded in which the ingestion of an Artemia metanauplius was traceable in its entirety [ILLUSTRATION FOR FIGURE 5 OMITTED].
The first motion of ingestion is a rapid outward fling of the paired appendages, followed by an inward squeezing action, bringing the endites of the maxillules into contact with the metanauplius as it enters the preoral chamber.
In four of the five multiple ingestion sequences analyzed, a newly captured metanauplius was used to push a partially ingested metanauplius into the mandibles.
Recorded phase 1 duration ranged from 0.2 to 5.9 s in sequences involving only a single metanauplius, and from 6.1 to 233.0 s in sequences involving two or more metanauplii.
Phase 2 begins with the first contact of the metanauplius with the mandibles and ends with the loss of direct contact with the prey item by the basal endites of the maxillules.
The maxillules and labrum press the metanauplius against the mandibles as the latter tear and grind the prey on its way into the mouth.
This phase of ingestion begins when the basal endites of the maxillules are no longer in contact with the prey, and continues until the entire metanauplius has passed through the mandibular region into the oral cavity.