FISHERY BULLETIN: VOL. 77, NO. 2 



from the cloaca. In young females 82-120 cm the 

 vagina is sealed or nearly sealed by a thin circular 

 membrane originating from the hymen. 



Cloaca 



The rectum opens into the cloaca ventrally and 

 forward of the vagina. A single urinary papilla is 

 located on the dorsal wall of the cloaca just poste- 

 rior to the hymen. Paired abdominal pores are 

 found on the dorsal wall of the cloaca (Figure 12). 



Copulation 



During copulation spermatophores pass from 

 the male ductus deferens to the urogenital sinus 

 and sperm sac. They exit ffom the sinus through 

 the common urogenital papilla which is positioned 

 over the apopyle of the clasper and partially fill the 

 clasper groove. The paired muscular siphon sacs 

 drive a water piston past the apopyle to force the 

 spermatophores through the clasper and into the 

 common vagina of the female through the uterus 

 and into the oviducal gland. Many females have 

 been observed to contain spermatozoa packed in 

 the greatly distended tubules of the oviducal gland 

 (Figures 14, 15). The motility of individual sper- 

 matozoa may play a part in entering the inner 

 tubules of the oviducal gland. 



From the presence of vaginal scars, Matthews 

 ( 1950) determined that the basking shark employs 

 one clasper at a time in copulation. Leigh-Sharpe 

 (1920) killed two tope "in copula" and observed 

 both claspers inserted. I have found unpaired 

 vaginal scars in female blue sharks caused by the 

 employment of a single clasper. Judging from the 

 size of the organs involved, the use of both claspers 

 simultaneously may be an option only for young 

 male blue sharks. 



Mating Injuries 



Wounds resulting from mating in large sharks 

 have been described by several authors. Springer 

 ( 1960) noted bite marks between the first and sec- 

 ond dorsal fins of the female sandbar shark, Car- 

 charhinus milbertt. He stated, "These are never 

 present on males or immature females and are 

 obviously produced during courtship." Suda 

 (1953) was the first to record tooth cuts on blue 

 sharks. In the Pacific, tooth cuts appear as early as 

 March and are most numerous from June to Au- 

 gust. Stevens (1974) conducted a study of tooth 



cuts on blue sharks in British waters. He divided 

 wounds into three types, semicircular impres- 

 sions, tooth slashes, and individual tooth nicks, 

 and recorded their distribution on the female. He 

 found tooth cuts only on female sharks >150 cm 

 and suggests that this is the size at sexual matur- 

 ity for the blue shark. 



Northwest Atlantic blue sharks bear dermal 

 wounds similar to those described as courtship 

 scars by Stevens (1974). Distinct tooth cuts have 

 been observed on females of 134 cm. (The smallest 

 female carrying sperm is 136.5 cm.) Occasionally 

 slashes and wounds resembling mating marks 

 occur on females as small 118 cm. External tooth 

 cuts are most extensive in female blue sharks from 

 145 to 200 cm long (Figure 16). Pregnant females 

 generally bear only older healed scars. Males of all 

 sizes are usually free of cuts. Wounds are so con- 

 sistently present on females that the fish being 

 tagged during longline or sportfishing operations 

 may be sexed from the dorsal surface without 

 examination of the pelvic appendages. 



To accommodate the male's aggressive mating 

 behavior, the skin over most of the body of the 

 mature female is more than twice as thick as that 

 of the male (Figure 17). The skin is thicker than 

 the males' teeth are long and only occasionally do 

 the wounds penetrate the dermis and involve the 

 musculature. Tooth cuts are generally punctures 

 or slashes made by the upper jaw only. Resistance 

 to infection and healing rates are apparently high 

 in the blue shark. Despite injuries that seem very 

 serious, evidence of infection and necrotic tissue 

 are notably absent. 



Matthews (1950) noted internal lacerations on 

 the thick vaginal pads of female basking sharks. 

 They are caused by the male's clasper claw, a 

 structure common to several families of elasmo- 

 branchs. 



The blue shark clasper does not bear a claw. 

 After insertion, the terminal end of the clasper is 

 flexed about 45°, unfolding and expanding the 

 sharp-edged rhipidion to form an anchor in the 

 vagina. The female often bears hematose abra- 

 sions on the otherwise light colored walls of the 

 vagina as a result of copulation. Specimens from 

 the Middle Atlantic Bight possess vaginal wounds 

 during all seasons examined (March-October). 

 Fresh marks are more frequent in summer months 

 while older dark purple scars are observed in 

 spring and fall. Spermatozoa have been found in 

 young females lacking vaginal wounds indicating 



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