Aquarium surprised by ‘virgin birth’ of swell shark in all-female tank

Baby shark Yoko hatched in early January, flummoxing staff and experts at a US aquarium

Birds do it, bees do it. Even educated fleas do it, according to Cole Porter's classic song on the universal nature of sex.

But a baby swell shark born in a Louisiana aquarium that houses only females has flummoxed marine experts and raised the possibility that the species may not require such earthly pleasures to produce offspring.