In Focus: Jawfish

In the vast majority of species, the females do the lion’s share of the child rearing. Notable exceptions include seahorses and pipefish, the males of which incubate their young in brood pouches, and birds such as emperor penguins and sandhill cranes.

Jawfishes – here the gold-specs jawfish Opistognathus randalli, photographed in Malaysia – also belong to this role-reversed parenting club. A father-to-be attracts a gravid female with a courtship dance, arching his back and spreading his pectoral fins. If sufficiently impressed, she will enter his burrow and lay her eggs. The male then fertilises the eggs and scoops them into his mouth, holding them until they hatch about a week later.

A male cannot feed during the brooding process, and must aerate his offspring from time to time by turning them. The larger the mouth, the more efficient the ventilation and the faster the fry will hatch – allowing their energydepleted dad to feed up and regain his strength for the next time.