A rare event has taken place in the Cala Gonone Aquarium in Sardinia, Italy. A smooth-hound shark gave birth to a baby shark without any male interference in the tank she has been living in for the past ten years with only another smooth-hound female and no males, reports Agenzia Italia. This could prove to be the first and only parthenogenesis example in this specific species of shark, and hence, the newborn female shark is named Ispera, which means Hope in Sardinian.
Virgin birth in animals
The surprising event is only thought to be due to parthenogenesis, literally greek for "Virgin Birth" (ring any bells?), an asexual reproduction model that needs no sperm to fertilize the egg. Parthenogenesis could be seen in species such as some reptiles, fish, and even birds that normally reproduce sexually, but it is especially favored in low-density populations, where females have little chance of meeting partners.
While other sharks and rays, including the bonnethead, the blacktip shark, and the zebra shark have previously been observed doing parthenogenesis, smooth-hound sharks, scientifically known as Mustelus mustelus, have never been, as far as scientists know. If confirmed, this event could be a scientific discovery of smooth-hounds' using parthenogenesis.
One of the most common traits of this type of reproduction is that the egg is fertilized by another still immature egg cell, which, in fact, behaves as a polar opposite, almost like a sperm. However, since the embryo is made up of the same genetic sequence, the offspring is always female since there is no Y chromosome in the making. And since there's no genetic variety, it's basically a clone of the mother. These offspring's genetic sequences are similar to those born of inbreeding and usually turn out to be weaker in health compared to the regular offspring. The good news is baby Ispera is reportedly in good health and is expected to live a normal life in captivity.
In an interview with Live Science, Demian Chapman, director of the sharks and rays conservation program at Mote Marine Laboratory & Aquarium in Florida, said that in the wild, parthenogenesis could be the last resort for females that cannot find a mate. In aquariums, separation from males or long periods of isolation can trigger this natural response in females.
Currently, this is only a hypothesis. Marine biologists at Cala Gonone Aquarium have sent DNA samples of the mother and the baby for further analysis so that it could be confirmed or denied.
While parthenogenesis could be a natural response to low chances of mating, this phenomenon usually stems from climate change's toll on animal populations, in addition to over-fishing and extreme isolation of species. As a result, some animals rely on self-reproduction to overcome dire circumstances. Though it may sound like a solution, this type of reproduction is not sustainable in the long run, and we can do our part in helping these depleting animal species to create a healthy habitat where they can reproduce naturally.