JOHNSON and HORTON: RATFISH, ASPECTS OF BIOLOGY 



Table 3. — Gyrocotyle found in 283 ratfish (Hydrolagus colliei) collected off the coast 



of Oregon, 1965-1967. 



Location 



Total number of Gyrocotyle'^ 



G. fimbriata 



G. 



Unidentified 



Newport 

 Astoria 

 Cape Arago 

 Cape Blanco 



50(34) 



8( 7) 



40(23) 



18(11) 



62(39) 



4( 2) 



38(25) 



^ Number in parenthesis is the number of ratfish Infested. 



^ Number in parenthesis is the percent infestation when alimentary canals that contained neither food nor para- 

 sites were excluded. 



males do not possess these structures but de- 

 velop paired oviducal openings not possessed by 

 males. Development of these structures can be 

 used to separate ratfish into young, immature, 

 and adult age groups. Young males have a 

 frontal tenaculum streak and diminutive claspers 

 (Figure 2) ; immature males have a small fron- 

 tal tenaculum and claspers which are not perfo- 



rated at their free ends (Figure 3) ; and mature 

 males have a well-developed frontal tenaculum 

 and well-developed claspers which are perforated 

 at their free ends (Figure 4). Young females 

 have no oviducal openings (Figure 2) ; the ovi- 

 ducts of immature females have small openings 

 (Figure 3) ; and mature females have oviductal 

 openings which are large, elongated, and swollen 



M 



METRIC 



Figure 2. — Regions of young ratfish showing (A) the frontal tenaculum streak, and 

 (B) the small claspers of the male; and (C) the absence of a frontal tenaculum streak, 

 and (D) the absence of oviductal openings in the female. 



425 



