Sentence:  The oval body, with the abdomen not yet differentiated, and bearing no limbs; the (usually) three pairs of limbs, representing the first and second antennæ and mandibles of the adult, together with the single eye, are the distinguishing characteristics of the <WSD>nauplius</WSD> stage. 
Meaning of the word marked with <WSD> tags:  A crustacean larva that has three pairs of locomotive organs (corresponding to antennules, antennae, and mandibles), a median eye, and little or no segmentation of the body. (from mid 19th c.)