Ocean wildlife

The Strange World of the Sunfish

by Annette J Beveridge

The oceans are filled with strange creatures and the sunfish is no exception. Using their large dorsal and anal fins to swim, they can move at speed when avoiding predators or, when they locate prey but are mostly seen simply drifting in the ocean currents. They are the heaviest of the bony fish weighing up to 1500 lbs – their size is impressive and they dwarf divers who are fortunate enough to swim with them. At birth, they have a back fin but this disappears as they mature. It appears to fold into the fish itself. Lying on one side as they manoeuvre through the ocean, these are spectacularly odd-shaped fish that have been mistaken for sharks when they emerge from the depths.

Descended from bony ancestors, the sunfish has cartilaginous tissues which is lighter than bone and as an adaptation, enables the fish to grow to an immense size. The teeth are fused – resembling a beak and they are unable to close their mouths. Sunfish have few enemies once they reach maturity but they do fall foul of boats when floating just beneath the surface and are at risk of becoming entangled in drift nets. Immature sunfish are predated on by sharks, whales. or sea lions.