A female zebra shark at Chicago‘s Shedd Aquarium unexpectedly gave birth to a litter of pups without the presence of a male.
The aquarium stated that the female shark, known as Bubbles, gave birth to the pups in the same tank as several other adult zebra sharks. It was previously thought that the female shark used sperm from a male shark to reproduce.
Most invertebrates give birth without the help of a male. This process is called parthenogenesis. Before now, it was believed that sharks only resorted to asexual reproduction when all other mating options had been exhausted.
Only two other cases of a shark giving birth without any adult males present have been documented up to this point.
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It turned out that the slow swimmers had given birth via parthenogenesis. A form of asexual reproduction that is more common in invertebrates like starfish and is also referred to by that name. Although asexual reproduction in sharks is possible, it is exceedingly rare and has typically been attributed to a lack of available males.
Researchers at the Field Museum in Chicago have known for some time that parthenogenesis occurs in animals like sharks, but the reasons for this and the events that set off this process have not been fully understood.
The co-author of a study on the case, which appeared in the Journal of Fish Biology, commented that the finding “throws a wrench in what we thought we knew about how and why parthenogenesis happens,” highlighting an essential aspect of science: we’re continually learning.
This is only the second known instance of a shark giving birth to a fertile offspring without the help of a male, and it is an extremely rare occurrence.
