Medium-size to moderately large animals (to 40 mm). Body slender, elongate, transparent. Head subconical, widest dorsally. Eyes composed of larger dorsal part, smaller, bulging, ventrolateral part. Pereonites I and II may be fused. Coxae fused with pereonites. ANT I in males multi-articulate, with large broadened first ART of flagellum, covered by fine setae; in females short, 2-articulate. ANT II in males multi-articulate or absent, in females reduced to tubercle. MD without palp. P I and II simple, weakly chelate, or subchelate. P III, IV, VI and VII simple, thin, linear. P V longest, distinctly or strongly subchelate. P I-IV have additional cristate lamellae near the dactyls (these structures were described in detail by Zelickman and Por, 1996, and are not discussed here). UR with free rami. Telson very small.
Genus Phronima Latreille, 1802
Genus Phronimella Claus, 1872
Phronimidae are noted for preparing barrel-shaped houses from bodies of salps or nectophores of calycophore siphonophores by eating away parts of those animals. Phronimidae find shelter and rear their young in such gelatinous houses. The French name "Tonnelier de mer" ("Marine coopers") derives from this habit.