Jellyfish and other gelatinous zooplankton are the most common prey of the ocean sunfish. However, they also feed on squid, crustaceans, sponges, brittle-stars, eel grass, small fishes and mollusks. Ocean sunfish can forage near the surface, in areas with abundant seaweed, but also in deeper areas, on the seafloor. Despite their large size, ocean sunfish only feed on small prey due to their small and fused jaws.
The length of most species of ocean sunfish is 6 feet, in average, while the weigh is about 2200 lbs. However, some sunfish can weigh as much as 5,000 lbs. and measure 11 feet, according to the National Geographic. Ranzania laevis, or the slender mole, is the smallest species, rarely measuring more than 4 feet in length. Ocean sunfish vary in color, but are often gray with grayish-to-white patterns, sometimes showing an iridescent sheen. Color varies according to geographic area. Sunfish found in Bali, for instance, are often darker than those living in Southern California.
Although the biological classification of ocean sunfish has changed many times in the past, four species of sunfish are currently recognized: the roundtailed or common mola (Mola mola), the sharp-tailed mola (Masturus lanceolatus), the slender mola (Ranzania laevis) and the southern mola (Mola ramsayi). Although most sunfish species are distributed throughout temperate and tropical oceans, Mola ramsayi is only found in the southern hemisphere, especially in the Pacific Ocean.
The common sunfish can host more than 40 different genera of parasites, including crustaceans, worms and amoebas. The species has a thick and rubbery skin, measuring up to 3 inches in thickness. Predators of sunfish include orcas and more often sea lions, which rip off the fins and sometimes abandon the prey still alive. The remains of sunfish that reach the seafloor feed bat stars and other species of starfish.