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Notostraca (tadpole shrimps; subphylum Crustacea, class Branchiopoda) Order of branchiopods in which the head and anterior trunk are enveloped by a large, shield-like carapace. The first antennae are absent, and the second pair are vestigial. The sessile compound eyes are close together beneath the dorsum of the carapace. The highly flexible abdomen bears up to 70 paired appendages, and culminates in a pair of long processes (caudal furcae). Tadpole shrimps inhabit temporary pools in desert areas, and their resistant eggs may survive 20 years or more of being blown about in desert dusts. There are 15 species.