Mola Mola

The ocean sunfish, or mola, is the heaviest known bony fish, capable of reaching weights over 1,000 kg. Belonging to the family Molidae, it has an extraordinary, flattened, disc-shaped body that appears truncated at the rear, giving the impression of a fish with no tail. This unusual shape results from the clavus, a rudder-like structure formed from modified fin rays that replaces the tail found in most fish. Mola mola are found in temperate and tropical oceans worldwide, typically in open water, and are frequently observed basking sideways at the surface, a behavior thought to aid thermoregulation and allow small fish and birds to remove parasites from their skin. The species is currently listed as Vulnerable due to bycatch in commercial fishing operations.

How to recognize an ocean sunfish:

• Enormous, flattened, disc-shaped body with a truncated, tail-less appearance
• Small, beak-like mouth and small eyes relative to body size
• Tall, pointed dorsal and anal fins mirrored above and below the body
• Thick, rough, silvery-grey to brownish skin, often mottled or blotchy
• Adults commonly measure 1.8-3.3 m in length and can weigh well over a ton

The mola's unmistakable truncated rear end and giant disc-like silhouette make it nearly impossible to confuse with any other fish species.

Ocean sunfish inhabit temperate and tropical waters throughout the world's oceans, ranging from near-surface waters down to depths of several hundred meters during deep foraging dives in search of jellyfish. They are typically found in open ocean environments but also approach coastal areas and productive current systems where jellyfish and other gelatinous prey are abundant. Mola mola are frequently observed basking motionless at the surface, a behavior believed to help them warm up after deep, cold dives and to attract cleaner fish and seabirds that remove parasites from their skin.

Ocean sunfish feed primarily on jellyfish and other soft-bodied gelatinous zooplankton, though they also consume small fish, squid, and crustaceans. They frequently perform deep dives into cold water in search of prey, then return to the surface to bask and rewarm in the sun, a behavior also thought to aid parasite removal by cleaner fish and seabirds. Mola mola are among the most fecund vertebrates known, with females capable of releasing hundreds of millions of tiny eggs in a single spawning event, though survival to adulthood is extremely low. They are generally solitary, slow-moving drifters that rely on ocean currents and only modest swimming effort to travel long distances.