Molidae

The Molidae comprise the family of the molas or ocean sunfishes, unusual fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-fish" appearance. They are also the largest of the ray-finned bony fish, with the ocean sunfish Mola mola recorded at up to 15 ft (4.6 m) in length and 2,000 kg (4,400 lb) in weight.

Description

Molidae have the fewest vertebrae of any fish, with only 16 in Mola mola. They also completely lack all caudal bones, and most of their skeletons are made of cartilage. No bony plates occur in the skin, which is, however, thick and dense like cartilage and is fairly rough. They also lack swim bladders.

Molids mostly swim by using their anal and dorsal fins; the pectoral fins are probably just stabilizers. To steer, they squirt a strong jet of water out of their mouths or gills. They can also make minor adjustments in the orientation of the anal fin or the dorsal fin so as to control the amount of force it produces and the angle at which the force is produced. In this respect, they use their fins much like a bird uses its wings.