FISHERY BULLETIN: VOL. 81. NO. 2 



(puncture wounds and torn gut) a 51 mm embryo 

 (drawn to scale; Fig. 14A). Having already developed 

 teeth, the 51 mm embryo (see Figure 11 of a 49 mm 

 embryo) had a potential for competitive interaction 

 with the larger 100 mm embryo, although at a 

 decided size disadvantage. It is possible that the 51 

 mm embryo had not hatched prior to the attack. 

 However, empty and broken egg capsules were not 

 found in the uterus. There is no evidence that the 100 

 mm embryo had tried to consume any of the other 8 1 

 egg capsules in the uterus, nor were there broken or 

 damaged capsules in the opposite uterus which con- 

 tained a 127 mm hatched embryo. 



We obtained further evidence that hatched em- 

 bryos and/or encapsulated embryos are selectively 

 preyed upon by their larger siblings within the uterus. 

 Two embryos (45 and 49 mm) in the right uterus of an 

 8 July 1978 female 0. taurus were badly damaged by 

 the attack of a 131 mm male embryo. Six empty egg 

 capsules were found within the same uterus. None of 

 the other 63 egg capsules were damaged (some of 

 which contained fertilized ova). In the left uterus, a 

 49 mm embryo had been mutilated by a 131 mm em- 

 bryo and two of the 66 egg capsules were empty. A 

 334 mm embryo from the left uterus of a 5 August 

 1976 adult 0. taurus had four embryos 9-36 mm TL 

 within its pharynx. Two damaged capsules still con- 



tained two embryos (35 and 41 mm), both of which 

 had been punctured numerous times through the 

 capsule membrane. Sixty-eight undamaged capsules 

 did not contain embryos. None of the 65 undamaged 

 capsules in the right uterus contained embryos. 

 However, this uterus contained an intact 41 mm em- 

 bryo with an egg capsule fragment within the 

 stomach of the largest embryo (320 mm). 



100 MM EMBRYO (IRCZM 103137, Fig. 14B).— 

 This male embryo was found in the right uterus of a 

 271.5 cm adult 0. taurus captured 18 July 1976. It 

 had well-developed fin rudiments and a particularly 

 well-developed caudal fin. The gill slits were large 

 and without external filaments. Both upper and lower 

 labial furrows were prominent. The yolk sac was 

 absent although an attachment scar was present. 

 Erect teeth, more slender than in previous embryos, 

 were present in multiple rows. The teeth lacked 

 lateral secondary basal cusps (basal denticles) typi- 

 cal of adult 0. taurus. The teeth of this embryo were 

 obviously functional because punctured and torn egg 

 capsules and a damaged (tooth-marked) 51 mm em- 

 bryo were found in the same uterus. 



131 MM EMBRYO (IRCZM 103103, Fig. 14C).— 

 A male embryo, from an 8 July 1978 sand tiger shark, 



1 cm 



Figure 14.— (A) A 51 mm Odontaspis taurus embryo attacked and damaged by (B) a 100 mm male embryo inside the uterus of a 271.5 cm 

 female captured 18 July 1976 (both IRCZM 103137). (C) A 13 lmm male embryo (IRCZM 103103) taken from the uterus of afemale captured 

 8 July 1978. This embryo had attacked and damaged the 49 mm embryo shown in Figure 1 1. 



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