The Shreveport Aquarium in Louisiana is investigating the mysterious birth of a baby swell shark, despite no male sharks being present in the tank for three years.

Yoko the swell shark was born in a habitat of all-female sharks who hadn't seen a male in years. The aquarium has two possible explanations — and hopes to get confirmation in the coming months.

When a shark egg appeared one day in a shark tank at a Louisiana aquarium, staff were puzzled. That’s because the tank only has two sharks in it — and they’re both female.

A small shark swimming around a Louisiana aquarium holds a mystery in its DNA. Yoko the swell shark hatched from an egg that was discovered in a puzzling place — an all-female tank, the Shreveport Aquarium announced.