Ocean Sunfish

Mola mola. Also common mola. Probably Mediterranean.Mounted specimen, late 19th century.

Ocean sunfish are very rare. At nearly two meters long, this specimen is one of the largest that has ever been mounted.

SWIMMING FRISBEES
Ocean sunfish are the heaviest known bony fish in the world. They can grow up to three meters long and weigh more than two tons. They cross the deep sea like vertically swimming frisbees. Their thick skin is scaleless, as raw as sandpaper, extremely elastic, and covered with a layer of slime. Instead of a tail fin, they have a clavus. Sunfish also have no ventral fin and no swim bladder. Because of this, they must keep moving constantly to keep themselves from sinking to the bottom. For this they use a dorsal fin and an anal fin that they move from side to side like a powerful rudder.
Sunfish are native to tropical and moderate oceans around the world. They eat jellyfish, octopus, seaweed, and small fishes. Their mouth is very small and is always open. Their teeth fuse together to form plates that look like parrots’ beaks. They drink in their prey with the water and only macerate it when it reaches their gullet. Sunfish are extremely fertile. A female can lay up to 300 million eggs in each spawning – more than any other species of fish.
Otherwise little is known about the life of these deep-sea inhabitants. They are usually caught as they lie flat on the surface of the water, as if sunbathing, which is also where the name sunfish comes from. The reason for this behaviour is still unclear. It may possibly help them absorb warmth; however, it is more likely that in this “cleaning position” sunfish attract sea birds with whose help they can get rid of the numerous parasites that infest their skin. Humans are quite likely to get quite a fright when they mistake the large dorsal fin of a sunfish for that of a shark.