Shark surprises Illinois zookeepers by reproducing without a male
CHICAGO (WGNTV) — The Brookfield Zoo has welcomed an epaulette shark pup to its team, but this baby shark's family tree is missing a few branches. According to the zoo, the female shark pup, who hatched on Monday, Aug. 23, was born through parthenogenesis, which is "when an embryo develops from an unfertilized egg cell."
Zoo officials say the pup's mother has not been housed with a male since she arrived at the facility in 2019 when she was 3 years old. Zoo officials say epaulette sharks reach sexual maturity at around 7 years of age.
Animal care staff at the zoo say the mother shark began laying between two and four eggs each month starting in 2022, which was typically infertile, but one egg laid within that period was fertile and after a five-month incubation period, the baby shark pup finally hatched. Staff say they believe the female shark was able to produce the fertile egg without needing to be fertilized by a male shark.
According to zoo officials, staff members had been monitoring the newly hatched baby shark behind the scenes, but after two months, the shark pup can now be seen by guests in a habitat inside the Living Coast’s entrance.
The shark pup currently measures around 5 to 6 inches long, but zoo officials say it could reach up to three feet when fully grown.
"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,” Mike Masellis, a lead animal care specialist at the zoo, said. “We are looking forward to guests being able to see the pup.”
Zoo officials say this is believed to be the second time a potential epaulette shark pup was produced via asexual reproduction at an Association of Zoos and Aquariums’ accredited facility. The first was recorded at an aquarium in New England, where the Brookfield Zoo’s adult females originated.
According to the zoo, parthenogenesis is a natural occurrence in some invertebrates but is less common in complex vertebrates.