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Head large relative to body
Rostrum usually long and acute
Adult body length generally greater than 1.25 mm
Head small relative to body with or without helmet
(h)
Small rostrum
(r)
Body length generally less than 1 mm
Taxonomy
Phylum
Arthropoda
Subphylum
Crustacea
Class
Branchiopoda
Suborder
Cladocera
Family
Daphniidae
Genus
Daphnia