Mola (fish)

A sunfish, also called a mola, is any fish in the genus Mola (family Molidae). The fish develop their truncated, bullet-like shape because the back fin, which is present at birth, never grows. Instead, it folds into itself as the creature matures, creating a rounded rudder called a clavus. Mola in Latin means "millstone" and describes the ocean sunfish's somewhat circular shape. They are a silvery color and have a rough skin texture.

The mola is the heaviest of all the bony fish, with large specimens reaching 14 ft vertically and 10 ft horizontally, and weighing over 6000 lb. Sharks and rays can be heavier, but they are cartilaginous fish.

Mola are found in temperate and tropical oceans around the world. They are frequently seen basking in the sun near the surface and are often mistaken for sharks when their huge dorsal fins emerge above the water. Their teeth are fused into a beak-like structure, and they are unable to fully close their relatively small mouths.

Ocean sunfish can become infested with skin parasites, so they will often invite small fish or even birds to feast on them. Sunfish will even breach the surface up to 10 ft in the air, in an attempt to shake off the parasites.

They are clumsy swimmers, waggling their large dorsal and anal fins to move, and steering with their clavus. Their food of choice is jellyfish, though they will eat small fish and huge amounts of zooplankton and algae, as well. They are harmless to people, but can be very curious and will often approach divers.

Their population is considered vulnerable, as they frequently are snagged in drift gill nets and can suffocate on sea trash, like plastic bags (which resemble jellyfish, their main food source).

Taxonomy
Kölreuter in 1766 published a fish name Mola but did not treat is as a Linnaean genus (i.e., not binominal), so the name is unavailable under the rules of the ICZN and cannot be used. The first author who used the name Mola as a genus name was Linck in 1790, and this is therefore the oldest available name, with Tetraodon mola Linnaeus, 1758 as its type species.

Species
There are currently 3 recognized species in this genus:
 * Mola mola (Linnaeus, 1758) (Ocean sunfish)
 * Mola alexandrini (Giglioli, 1883) (Southern sunfish)
 * Mola tecta Nyegaard et al., 2017 (Hoodwinker sunfish)