 Known predators of the viper dogfish include the bigeye tuna ( Thunnus obesus ) and the sickle <unk> ( <unk> <unk> ) . Like other members of its family , this species is viviparous with the developing embryos sustained to term by yolk . Adult females have two functional ovaries and two functional uteri . Two of the recorded female specimens contained 25 and 26 mature ova ; in the related black dogfish ( Centroscyllium fabricii ) , the number of mature ova in a female is slightly greater than the number of resulting embryos , which suggests a litter size under 26 in the viper dogfish . Males and females mature sexually at roughly 43 and 52 cm ( 17 and 20 in ) long , respectively . 
