"Shark Spectacle: Rare Parthenogenesis Births Adorable Epaulette Pup at Brookfield Zoo

Breaking away from the expected, an epaulette shark pup, born through apparent parthenogenesis, is making waves at Brookfield Zoo near Chicago. In a twist resembling a storyline from the infamous 'Baby Shark' song, this real-life Mommy Shark has defied norms by producing offspring without the presence of a Daddy Shark.

The baby shark hatched during the summer, and its mother, residing at the zoo since 2019, has never shared a tank with a male. This unique occurrence is identified as parthenogenesis, a form of asexual reproduction, as confirmed by the zoo. Starting in 2022, the adult female shark consistently laid two to four eggs each month, typically infertile. However, one of these eggs proved fertile, and after a five-month incubation, the pup emerged. Currently, the 2-month-old pup measures about 6 inches but has the potential to grow into an adult shark spanning 2-3 feet.

While sharks are generally fish and not mammals, this virgin-born epaulette pup is captivating hearts at the intersection of cuteness and curiosity. With large false eye spots resembling epaulettes, these sharks are known for their ability to walk not only on the seafloor and coral but also on land.

Mike Masellis, a lead animal care specialist at the zoo, shared, "We are happy to report that our epaulette pup has been eating well on her diet of finely chopped capelin, minced squid tentacles, and other finely chopped seafood. We are looking forward to guests being able to see the pup."

This case marks the second known instance of apparent asexual reproduction producing an epaulette shark pup in an accredited zoo or aquarium. The first was reported at the New England Aquarium in Boston, where the Chicago Zoo acquired its adult epaulette females. Staff at Brookfield Zoo have been collaborating with their counterparts at the New England Aquarium to ensure the successful nursing of the young pup during its early months.

Parthenogenesis, a phenomenon well-documented in insects and reptiles and observed in birds and fish, was only recently confirmed in sharks. The birth of this adorable epaulette pup adds another fascinating chapter to the evolving understanding of reproduction in these underwater wonders."

"Shark Miracles: A Look Back at Pioneering Cases of Parthenogenesis in Sharks

The recent birth of an epaulette shark pup through parthenogenesis at Brookfield Zoo is not the first time sharks have defied traditional reproductive norms. Around 22 years ago, female bonnethead sharks, a type of hammerhead, astounded researchers at the Henry Doorly Zoo in Nebraska by undergoing "astonishing virgin births." These births occurred despite the prolonged absence of male sharks, and genetic analysis revealed no evidence of paternal DNA in the offspring.

In the case of these bonnethead sharks, the specific type of asexual reproduction observed is known as automictic parthenogenesis. Unlike traditional sexual reproduction, where an egg combines with sperm, automictic parthenogenesis involves the use of a polar body—a byproduct of germ cells undergoing meiosis to produce eggs. Typically, polar bodies containing chromosomes are reabsorbed into the female's body. However, during parthenogenesis in sharks, one polar body, which would normally be reabsorbed, acts like a sperm and fuses with the cell destined to become an egg.

Shark expert Mahmood Shivji explained in a 2007 NPR interview that the outcome is a fertilized egg with the normal complement of chromosomes but lacking the full genetic diversity associated with sexual reproduction.

The groundbreaking discovery two decades ago showcased the potential for female sharks to reproduce without male involvement. Unfortunately, the bonnethead shark born through parthenogenesis in that instance faced a tragic fate—it was attacked and killed mere hours after hatching.

In contrast, the 2-month-old epaulette shark born through parthenogenesis at Brookfield Zoo has found a more fortunate destiny. Recently on display in the zoo's Living Coast exhibit, this pup serves as a living testament to the remarkable and evolving understanding of shark reproduction, highlighting the mysteries that continue to unfold in the world of these underwater wonders."

"In conclusion, the recent birth of an epaulette shark pup through parthenogenesis at Brookfield Zoo opens a fascinating chapter in the ongoing exploration of shark reproduction. This event echoes back to a groundbreaking discovery approximately 22 years ago, when female bonnethead sharks showcased astonishing virgin births in the absence of male counterparts.

The specific form of asexual reproduction seen in sharks, known as automictic parthenogenesis, challenges traditional reproductive norms. Instead of the conventional combination of an egg with sperm, this process involves the utilization of a polar body—a unique aspect of germ cell meiosis. In the case of shark parthenogenesis, a polar body that would typically be reabsorbed acts like a sperm, leading to the fusion with the cell destined to become an egg.

While the earlier bonnethead shark born through parthenogenesis met a tragic end, the 2-month-old epaulette shark pup currently on display at Brookfield Zoo represents a fortunate continuation of this reproductive marvel. Serving as a living testament to the mysteries of shark reproduction, this pup captures the attention and curiosity of researchers and zoo visitors alike, emphasizing the ongoing exploration of the underwater wonders that continue to unfold in the realm of shark biology."