Female shark pup born through parthenogenesis (without fertilization)
Brookfield, Ill. — On August 23, an epaulette shark pup hatched at Brookfield Zoo. The hatching wasn’t unusual, but what is, is the way the shark embryo developed. The adult female shark had not been housed with a male since arriving at the Zoo in 2019. At that time, she was only 3 years old, and the species reaches sexual maturity around 7 years of age. Under these circumstances, animal care staff believe the female produced a fertile egg without needing to be fertilized by a male’s genetic material. This reproductive process known as parthenogenesis is when an embryo develops from an unfertilized egg cell.