Looking like something that stepped straight out from the pages of a sci-fi novel, the Mola Mola is one of the most bizarre looking fish to call the ocean home. Resembling a giant floating pancake with fins that look like Dumbo the Elephants’ ears, the Mola Mola (or sunfish) is the largest bony fish in the ocean. Reaching over 3 .5 m wide and weighing over 2 000 kilograms, these funny looking fish are a rare treat to dive with.
The Mola Mola looks like it’s missing a tail, which technically it is. Sunfish are born with a back fin, but this fin never develops after this early stage of life. As the huge fish matures, the back fin folds into itself and begins to form a rounded rudder as the fish grows, referred to as a clavus. Sunfish aren’t the most graceful of swimmers, propelling themselves underwater with their anal and dorsal fins and using this clavus to steer their enormous weight through the ocean.
Sunfish spend most of their adult life in temperate and tropical deep water, only coming into shallower water to visit cleaning stations. Mola Molas’ rough, silvery skin can become so infested with parasites that they will seek out small fish or birds to pick them off, lying on the surface of the ocean as their parasitic problems become another species lunch. Oceanic Sunfish can play host to up to forty different species of parasite, so cleaning sites provide some much needed relief for these giant harmless fish.
The aptly named ‘Sunfish’ is known for spending time on the surface, lazily basking in the sun. It is believed that they do this prior to a deep dive (mature sunfish can dive to over 200m and have been recorded at depths of 600 metres) or after returning from one, to warm their bodies up. A team of scientists from the University of Tokyo recently discovered the sunfish swim back and forth between the surface every day, returning to the bask in the sun in between feeds to warm their bodies. In comparison to the vast surface area of the fish, the team found that the sunfish were able to re-heat their bodies after a deep sea forage surprisingly quickly, which suggests that these fish have some sort of physiological mechanism to do this.
Just like most species of sea turtle, a favourite food of the Sunfish is jellyfish. Up until recently, it was thought that Mola feed exclusively on jellies. New evidence shows that Sunfish also eat marine hydrozoans, a tiny species related to jellyfish. These hydrozoans live in waters between 50 – 200 metres deep, explaining why the Sunfish dive to such extreme depths. After chowing down on their tiny jelly meal, they return to the surface to re-heat their bodies, like a floating solar panel. Sunfish have a mouth perfect for making meals of gelatinous species, with two hard teeth plates that it uses to suck the jellies into its mouth. Sunfish can even eat species that others would normally receive a painful sting from, thanks to a thick layer of mucus in its digestive tract.
Diving with Mola Mola is a must-do, and there are a few top places where your chances of seeing this unique fish are increased.
Nusa Peninda and surroundings, Bali
This area of Indonesia provides a perfect environment for the Mola Mola, and is one of the best spots to see Sunfish. Islands surrounded by deep chasms, and shallower reefs for Sunfish to come in and visit a cleaning station mean your almost always guaranteed to see these beautiful fish.
There’s few species you won’t see in the Galapagos Islands. A divers wonderland, with an array of marine life that is well protected, Mola can be spotted in the chilly but magical waters of Punta Vincente Roca.
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