KIDNEY 



FISHERY BULLETIN: VOL 77. I 



DUCTUS DEFERENS 



POSITION OF KIDNEY IN SHARK 



Figure 4. — Male urogenital complex in the blue shark. 



Sperm Sac 



The sperm sac ( Figure 4 ) is not well developed in 

 the blue shark. This paired organ communicates 

 with the anterior end of the urogenital sinus 

 through an opening between the paired terminal 

 papillae of the ductus deferens. The diameter in a 

 mature 200 cm male was 16 mm at the sinus. The 

 sperm sacs lie along the dorsal midline of the body 

 cavity and extend anteriorly into the kidney ap- 

 proximately 15 cm, where the tubes taper down to 

 threads and end blindly. 



Siphon Sacs and Claspcr 



In the adult blue shark the paired claspers are 

 heavily calcified scroll-shaped appendages which 

 transfer sperm from the lower ductus through the 

 urogenital papilla to the vagina of the female dur- 

 ing copulation. Propulsive force is provided by a 

 water piston driven by the muscular subdermal 

 siphon sac associated with each clasper. An accu- 

 rate description of clasper morphology and func- 

 tion is given by Leigh-Sharpe (1920). The clasper 

 is similar in form to that of the basking shark, 

 which has been described in detail by Matthews 

 ( 1950) and to the tope, Galeorhinus galeus (Leigh- 

 Sharpe 1921). The blue shark lacks a distinct spur 

 or clasper hook and uses instead the sharpened 

 edges of the terminal parts, which are splayed 

 open after insertion to secure the clasper in the 



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FIGURE 5 —Spermatozoa of the blue shark < x 1,600). 



