A Quick Look At A Sharks Life Cycle
A sharks life cycle is very interesting. We don’t really know that much about their life cycle because man has not been able to study many of the mating, birth, and lives of the over four hundred species of sharks that populate the world.
Of the over four hundred species of shark, there are only a few that have been maintained in captivity for any length of time and these are the species that most of the “averages” discussed in research are based upon.
A shark gestates from nine months to two years. There are three methods that sharks gestate, which include the ovoparity method. This is when the shark lays eggs that are soft leather-like cases and screws the eggs into cracks and crevices that will protect the pups from predators. When the eggs are screwed into the crevice or crack, they get very hard and keep the egg in place until the pup is born.
Some sharks carry their eggs in the womb, called the ovoviparity method. When a pup hatches from the egg it feeds on the other eggs in the womb and the fluids, then is born fully developed and functioning. The viviparity method is the same as mammals. The pups are carried in a placenta, nurse and are weaned there and then are born and swim away from the mother.
If sharks were like other fish that lay several hundred eggs in a year and have hundreds of hatchlings, they would not be endangered. But, because fishermen kill between 30 and 100 million sharks each year over the world, there are over 80 species threatened with extinction. Sharks do not mate until they are in their teens and only have one or two pups every year or two. There is no regulation on the hunting of sharks and they do not have the time to procreate in the numbers that they are being killed.
On average, a shark lives up to twenty-five years. But, remember that there are no real statistics on sharks that we have not been able to study. No one knows for sure how long a Great White lives. A Great White that is being followed in the wild is currently 25 years old. There are Whale Sharks living that are thought to be at least 100 years old.
Studying sharks has always Seiji Tadashi’s passion for as long as he can remember and has always pondered about the sharks life cycle.
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