Importance of Chemicals
As a female shark reaches maturity, it is able to produce certain hormonal chemicals to attract a mate. Each species of shark emits a different chemical, dependent on its genus, though some sharks emit very similar chemicals.
Once the female shark has signaled that it is ready to mate by releasing its chemicals, the male sharks who are interested begin to circle the female. This can lead to some male sharks fighting each other to win over the female. Once the dominant male has prevailed, the sharks will begin the mating process.
In some shark species the male shark may bite the female shark. This is the way that the male shark expresses that he is interested in mating with the female shark. However, the female shark usually makes it through this process unharmed because its skin is much thicker than that of the male shark.
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The male shark's anatomy includes a clasper on each side of it's body. This clasper allows the male to inject it's sperm into the female shark and impregnate it. After the process is over, the male will leave, allowing the female to carry and give birth to shark without help or interference from the male.