Ask The Aquarium: Q. We catch sunfish in a river nearby. I heard there are sunfish in the ocean and they are much bigger. Do they have a season?
- Published on Sunday, 13 May 2012 02:31
- Written by Super User
Alex Wazlak snapped this photo of a young mola off Oregon Inlet. Despite their colossal size at maturity, molas are harmless to people but can be very curious, often approaching divers to investigate.
ANSWER. You’re most likely referring to the ocean sunfish, Mola mola. This gigantic fish is not related to freshwater sunfish, and you probably wouldn’t want to catch one. Two other mola species swim the world’s oceans; the sharp-tailed Masturus lanceolatus and the slender Ranzania laevis.
Molas are the heaviest of all the bony fishes. They can reach 14 feet vertically and 10 feet horizontally and weigh nearly 5,000 pounds! The general range of these tremendous fish is Newfoundland to South America, but they can be found in temperate and tropical oceans worldwide. Molas are perhaps one of the most oddly shaped creatures in the sea. In Latin, mola means millstone, aptly describing the fish’s somewhat circular shape. Its rough-skinned body is primarily head and fins. The truncated shape is due to its stubby back fin, which during development, folds into itself and grows into a rounded, rudder-like fin called a clavus.
Molas are silvery in color, but like many fishes they can quickly change color when disturbed or stressed. Appearing like enormous silver disks in the sea, they are frequently seen basking in the sun near the surface. They’re often mistaken for sharks when their huge dorsal fin emerges above the water. For such huge fish, molas have small mouths filled with teeth fused into a beak-like structure.
Their food of choice is jellyfish, although they also eat small fish and huge amounts of zooplankton and algae. Observers of these ocean giants usually describe them as clumsy swimmers; however, this is believed to be sightings of sick or dying individuals. Molas are powerful swimmers, using their high dorsal and anal fins in a sculling motion and steering with their rudder-like clavus. Like many fishes, they attract skin parasites and can become so infested that they invite small fish or even birds to feast on the irritating hitchhikers. Molas have been known to breach the surface up to 10 feet in the air and land with a splash in an attempt to shake off parasites.