Hammerhead Sharks, the Blue Shark, Bull Sharks and
Smoothhounds are viviparous
shark species. This means that the female keeps her embryos inside
her oviduct, feeding them from a placenta, until they are ready to
be born.
Mating occurs between a male and a female shark,
during which the male will insert his clasper in to the females
oviduct and deposit sperm. This sperm then fertilises several of her
eggs. The number of fertilised eggs and resulting embryos depends on
the shark species and can range from just a few to several dozen.
Once the eggs have been fertilised, a placental link is created
between the embryo and the nutrient-rich placenta.
During the gestation period, which is usually fairly
long but differs in length amongst the species, the young pups are
sustained within the mother. The placenta provides all of the
nutrients that the embryo needs. This gives them the opportunity to
develop and mature as far as possible so that they are born strong
and healthy, able to fend for themselves.
Once fully developed, the pups are born alive into
the ocean. They immediately leave the vicinity of their mother, who
automatically becomes a predator, to live, hunt, mate and migrate
independently. The process up until their birth has resembled that
of so many mammalian species, including human beings. However, after
birth, the mother does not nurse or care for her young. Rather, they
are merely viewed as her next potential meal. This sets this unique
group of animals apart as instinctual, born hunters.