Sentence:  "Fairy-shrimps" are primitive crustaceans, most of which live in temporary ponds, roadside ditches, or marshes that dry up in sumer. They lay thick-walled eggs that withstand summer drying and winter freezing, lying dormant in the mud until they hatch out as <WSD>naupliuses</WSD> when wetted by the first heavy spring rain. 
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.)