Noun
protozoea (uncountable)
(zoology) A group of larval stages in the growth of decapods in which the antennae are used for movement, and mandibles for chewing.
By the second protozoea, segmentation appears on the pleon, and by the third protozoea, which may also be called the metazoea, the uropods have appeared. Source: Internet
The pleon (abdomen) is unsegmented in the first protozoea, and ends in a bilobed telson, which may be used for cleaning other appendages, or for steering. Source: Internet