ABSTRACT
Like mammals, all elasmobranchs have internal fertilization and most have long gestation periods, up to 22 months in the spiny dogfish, Squalus acanthias, and as long as 3.5 yr in the frilled shark (Chlann;doselachus anguineus) (Tanaka et a!. 1990). ln elasmobranchs, extended development may produce a central nervous system capable of mediating complex social and sexual behavior (Demski 199Gb). A high degree of sophistication has been revealed by investigations into interactions of large groupings of scalloped hammerheads, Sphyrna lewini (Klimley 1987), dominance hierarchies in sand tigers, Carcharias taurus (Gordon 1993), and complex pair and group mating behaviors in nurse sharks, Ginglymostoma cirratum (Carrier et a!. 1994).
