HOUDEi DEVELOPMENTAL ABNORMALITIES OF Achiru, l^ratus 



Figure 7.— Leftside (upper photo) and right side (lower 

 photo) of 66.0 mm TL abnormal Achirus lineatus reared 

 in the laboratory. Partial albinism, hooked dorsal fin, 

 no eye migration. 



all four major anomalies and 16 to 23 specimens 

 had two or three coexistent aberrancies. The 

 "rule" of Gudger and Firth (1936), that was 

 supported by extensive data on flatfishes (Daw- 

 son, 1962), stated that specimens with complete 

 pigmentation of the body and pigmentation cov- 

 ering at least one-quarter to one-third of the head 

 on the blind side will have a hooked dorsal fin 

 and incomplete eye migration. Five of my lined 

 soles fitted that category of ambicoloration but 

 had neither a hooked dorsal fin nor incomplete 

 eye migration (Table 1 and Figure 5). All but 

 two ambicolored specimens also were abnormal 

 in some other respect. Ambicolored individuals 

 in which the body and more than 10 ^f of the 



head on the blind side were pigmented retained 

 a pectoral fin on the blind side. Eye migration 

 never was complete in those specimens with a 

 hooked dorsal fin. 



A single specimen (Figure 7; *86 in Table 1) 

 was unique in that the left eye completely failed 

 to migrate. A portion of the right side of its 

 head was unpigmented making it the only par- 

 tially albinistic specimen in the series. The left 

 side, which was unpigmented and lacked a pec- 

 toral fin, was similar in these respects to the 

 blind side of normal lined soles. A well-devel- 

 oped hooked dorsal fin was present. Similar 

 abnormalities were present in a naked sole 

 (Gymnachmis melas Nichols) that was reared 

 at the laboratory. 



The high percentage of abnormalities in lab- 

 oratory-reared A. lineaUis must have been in- 

 fluenced by rearing conditions, since abnormal 

 lined soles apparently are extremely rare in 

 nature. Further controlled experiments should 

 make it possible to determine what factors cause 

 abnormal metamorphosis of lined soles and per- 

 haps other flatfishes. These experiments also 

 might test the common assumption that survival 

 of abnormal flatfishes is lower than that of nor- 

 mally metamorphosed individuals, since no ad- 

 vantages in either survival or growth of normal 

 juveniles of A. lineatus were detected in the ini- 

 tial rearing experiment. 



ACKNOWLEDGMENTS 



Assistance in rearing the larvae was provided 

 by Barbara Palko and Robert Detwyler. Charles 



Figure 8. — Left side of a reversed, nearly metamor- 

 phosed, 5.5 mm TL specimen of Achirus lineatus reared 

 in the laboratory. 



543 



