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How do sharks reproduce?
We know a great deal about certain aspects of elasmobranch reproduc-
tion. Or at least we know much about the things that can be studied by
dissecting dead fish. We know comparatively less about the behavior and
ecology of reproduction, although our understanding is growing.
Certain behaviors occur in several of the species whose reproduction
we have been able to observe. Mating in elasmobranchs can be an elabo-
rate and sometimes violent affair, at least by human standards. For exam-
ple, males follow closely behind females for varying lengths of time—a few
minutes in Nurse Sharks but as much as six hours in Basking Sharks. One
or several males may follow a female, depending on species. A male may
swim with his snout almost in contact with the female’s tail or even her
cloaca. In manta rays, males follow closely behind a female, duplicating her
every swimming movement. As many as 25 male mantas will follow a single
female in what is called a “mating train,” making for a group ballet perfor-
mance. Mating trains may last for more than a day. Courtship displays also
occur. For instance, a male Scalloped Hammerheads will approach a female
that is part of a group, bend his body, and stick out a modified pelvic fin
clasper. If the female is receptive to this display, the couple swims off as a
pair and copulates.
Actual mating begins when a male grabs onto a female the only way he
can, with his teeth. (In manta rays these are tiny, are only on the lower jaw,
and probably function just for mating.) A male may bite down on a female’s
pectoral fin, gill area, or body, holding her while he inserts one of his clasp-
ers into the female’s cloaca. Internal contact is maintained by barbs, hooks,
claws, and spines at the end of the clasper. In Blue Sharks, the clasper endsChapter 6
Reproduction
and Development
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