Ocean Sunfish - Range and Behavior

Range and Behavior

Ocean sunfish are native to the temperate and tropical waters of every ocean in the world. Mola genotypes appear to vary widely between the Atlantic and Pacific, but genetic differences between individuals in the northern and southern hemispheres are minimal.

Although early research suggested that sunfish moved around mainly by drifting with ocean currents, individuals have been recorded swimming 26 km in a day, at a top speed of 3.2 km/h. Sunfish are pelagic and swim at depths of up to 600 m (2,000 ft). Contrary to the general perception that sunfish spend much of their time basking at the surface, research suggests that adult M. mola actually spend a large portion of their lives submerged at depths greater than 200 m (660 ft), occupying both the epipelagic and mesopelagic zones.

Sunfish are most often found in water warmer than 10 °C (50 °F); prolonged periods spent in water at temperatures of 12 °C (54 °F) or lower can lead to disorientation and eventual death. Researchers theorize that surface basking behaviour, in which a sunfish swims on its side, presenting its largest profile to the sun, may be a method of "thermally recharging" following dives into deeper, colder water. Others point to sightings of the fish in colder waters outside of its usual habitat, such as those southwest of England, as evidence of increasing marine temperatures.

Sunfish are usually found alone, but occasionally in pairs or in large groups while being cleaned. They swim primarily in open waters, but are sometimes seen near kelp beds taking advantage of resident populations of smaller fish which remove ectoparasites from their skin. Because sunfish must consume a large volume of prey, their presence in a given area may be used as an indicator of nutrient-rich waters where endangered species may be found.