Parthenogenesis vs. sharks

The first question that probably teased your mind as soon as you read the title of this article is: "What is parthenogenesis anyway?"

Another question might be: "What is the link between parthenogenesis and sharks?"

When you read  the title "Parthenogenesis vs. sharks" it reminded you of a fight between two rivals. In fact, you are not that far off as it is a battle for the survival of males and their species.

How can this be? Well, let's start by answering your first
question: "What is parthenogenesis anyway?" Parthenogenesis is a process that allows certain animals to reproduce asexually, which means without the involvement of a male. 

Certain species have been known to use parthenogenesis as a way to reproduce themselves. These animals are: birds, amphibians, reptiles, bony fishes and now sharks.

Not all species of each type of animal is able to use parthenogenesis. This also applies to sharks as not all species have been known to reproduce asexually. In fact, only two cases of parthenogenesis have been reported in captivity. One specie laid eyes. Usually, these eggs were collected then thrown away by staff as they were considered to be infertile since only female white-spotted bamboo sharks occupied the tank.

As a member of the staff heard that three female sharks living in captivity and sharing the same tank welcomed the birth of a live pup, he decided not to disturb the eggs. His decision brought up positive results as the eggs hatched, adding two pups to the tank. It has proven that no male fertilization of the eggs was needed. 

The main problem with parthenogenesis is the fact that with the absence of male genes, only female sharks can be reproduced asexually, which could endanger the survival of males in species using parthenogenesis.

In the case of the three hammerhead females, which was also the first case of parthenogenesis reported in captivity, there was another theory that was studied as a possible answer to this natural phenomenon.

Since the DNA testing performed on the hammerhead shark pup, which died a few days later, possibly killed by a stingray in the tank, it matched the DNA of only one of the hammerhead females in the tank.

The fact that the gender of the shark pup was also female supported the theory of parthenogenesis. Another theory implied the storage of unused male sperm, which later fertilized the female.

This theory was based on facts established in other cases as some species have been known to store unused male sperm for a while. Since the female hammerhead was not born in captivity, this possibility was studied by the staff.

When was the first case of parthenogenesis reported in captivity? Well, the hammerhead pup was born in December 2001 at Omaha's Henry Doorly Zoo. Unfortunately, the seven inches long shark pup only survived a few days. It was reported that it was attacked by another fish attacked it. The culprit was said to possibly be a stingray.

The premature death of the shark pup meant that while it provided some answers to some questions, it also left a lot of questions unanswered.

Can shark species survive without males? Can the DNA imbalance provide some strengths or weaknesses in these species? Could it be the answer to the survival of some critically endangered species? Could it prevent the extinction of some species?

How often is it used into the wild? Is it possible to witness this process with most shark species, as long as they are in captivity? Can sharks reproduce asexually at a younger age without needing to reach their full maturity?

As we know, the sharks' mating ritual is very violent, which can sometimes be responsible for the female's death. You see, while mating, deep cuts and ferocious biting is involved as it is considered to be part of the mating ritual. Would parthenogenesis solve the mating problems for female sharks?

Do humans have the right to interfere by trying to develop the use of this type of reproduction in captivity? Since humans are responsible for endangering some shark species and causing the extinction of others, should they help a little?

There are so many unanswered questions that only research canpossibly answer with time. Either way, parthenogenesis is considered to be a miracle of nature. Or is it?

If you wish to learn more about the shark's anatomy, I invite you to visit this page: Shark Anatomy.