Chicago's Baby Shark Hatched From Egg Not Fertilized By Male Shark

A shark in a zoo in Chicago gave birth even though it has no contact with a male for four years. According to Brookfield Zoo, it was on August 23 when an epaulette shark pup hatched in the zoo.

The hatching was not unusual, but what is, is the way the shark embryo developed. The adult female shark had no sexual contact with a male since arriving in the said zoo in 2019.

"This epaulette shark has an exciting hatch day story. Sharks reproduce by laying eggs, but what's most interesting is this embryo developed without the need for male fertilization,'' the Brookfield Zoo representative said.

''This process, known as parthenogenesis, is relatively rare for complex vertebrates like sharks, and Brookfield Zoo is believed to be one of only two facilities that have had success in hatching epaulette shark pups produced by asexual reproduction," they added.

Exciting Hatch Story

At that time, the shark was only 3 years old, and the species reaches sexual maturity around seven years of age.

Under these circumstances, the animal care staff expressed belief that the female produced a fertile egg without needing to be fertilized by a male's genetic material.

This reproductive process is known as parthenogenesis wherein an embryo develops from an unfertilized egg cell.

Starting in 2022, the adult female shark began laying two to four, typically infertile eggs, on a monthly basis.

The zoo said that one of those eggs was fertile, and following a five-month incubation, the pup hatched and has been behind the scenes being monitored by the zoo staff.

The zoo said that at two months old, the approximately 5- to 6-inch shark can be seen in one of the habitats just inside the Living Coast's entrance.

The epaulette sharks can reach 2½ to 3 feet in length whenever they are fully grown.

Parthenogenesis is a natural occurrence in some invertebrates, but less so in complex vertebrates, including sharks.

Experts believed that this is the second Association of Zoos and Aquariums' accredited facility to report a potential epaulette shark pup produced by an asexual reproduction.

The first instance was recorded at New England Aquarium, where Brookfield Zoo's adult females originated.

"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. Our colleagues at New England Aquarium have been a great resource as shark pups produced parthenogenetically can be very delicate," said Mike Masellis, a lead animal care specialist at Brookfield Zoo.

"We are looking forward to guests being able to see the pup," Masellis added.

Epaulette Sharks

Epaulette sharks are described as mostly nocturnal creatures that were found in warm, relatively shallow waters over sandy bottoms from the southern coast of New Guinea to the northern coast of Australia.

The said species is able to tolerate extremely low oxygen environments and has been known to "walk" short distances on the seafloor and even land by using its muscular pectoral fins.

Experts said that in order to appear larger than it actually is, the epaulette shark has false eyespots behind its head.

Usually these eyespots resemble shoulder decorations on uniforms, which is how the species got its name.