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XIII. Family PHRONIMIDAE Dana, 1852 



Crustaceans of 10-40 mm in length, with thin transparent integument, the 

 head is very high and its longer axis perpendicular to the longitudinal axis 

 of the body; in a lateral view it is conical. The eyes occupy almost the 

 entire volume* of the head. The ocelli are divided into dorsal and lateral 

 groups. Antennae I In females are two-segmented, in males the peduncle 

 is three-segmented and the flagellum multisegmented. Antennae II are 

 absent in females, in males reduced or well developed; in the latter case 

 they have a thin multisegmented flagellum. The mandibles lack a palp, 

 maxillae I lack an inner lobe. Maxillae II are bilobate. The maxillipeds 

 have completely fused inner lobes while the outer lobes are narrow and 

 tapered. 



The pereon somites are free (Phronima) or the first two somites 

 are partly fused (Phronimella). The height of the pereon somites is 

 less than the height of the head; the last somite is the narrowest and 

 longest. The coxal plates are fused with the pereon. Pereopods V have 

 a strong, broad subchela or (Phronimella) long 5th-6th segments armed 

 with spines, which in the folded state form a less perfect subchela. The 

 gills are located on somites IV-VI and the oostegites on somites II-V 

 narrow, with non-contacting margins. The pleon is narrow. The rami of 

 the uropods are free. Uropods II are usually smaller than the others and 

 in the genus Phronimella rudimentar>-. The telson is small. 



All phronimids live in the surface zone of the ocean. Most of them 

 inhabit the tropical waters of the three oceans and with rare exceptions 

 do not cross the limits of the Subtropical Convergences. Females with 

 eggs or embryos are found in the plankton throughout the year. Sea- 

 sonal investigations have revealed, however, that some species multiply 

 predominantly in the spring and autumn (Repelin, 1970). 



The phronimids are often found in transparent barrel-shaped 

 cuirasses; hence they have been named "marine diogenes" or "tonneliers 

 de la mer" (marine coopers). These cuirasses are wide open on both 

 sides and composed of shells from the covers of pelagic tunicates 

 (salpids, doliolids and pyrosomids), siphonophores or even heteropods 

 (Firoloida). The Phronima eat the viscera of the prey and free the 

 transparent cover of all types of "architectural surpluses" — internal and 

 external outgrowths, keels, septa and so on. Later the crustacean uses 

 the cuirass as a hideout against enemies and for rearing the brood. 

 Attaching by the short pereopods V-VII to the inner wall, the Phronima 

 create a current of water by the energetic movement of the pleopods and 

 thus bring into motion their floating home. Meeting with an obstacle. 



* [sic] ; more correctly, the eyes occupy almost the entire surface of the head — General 

 Editor. 



