Scuba diving with Mola Mola in Bali is the dream of every diver.
Mola mola. Fun facts
1. Mola mola is the world’s largest bony fish
Some individuals reach extraordinary sizes of up to 4 meters in wingspan and weigh more than 2 tons. A marvel of the ocean in terms of size and weight!
Video by Ludovic Amevor
2. Sunfish live in the deep ocean, typically at an average depth ranging between 400 and 600 meters
3. Their closest relatives are pufferfish, triggerfish, and boxfish
Although at first glance it may not seem very similar in appearance, it shares the swimming style and mouth structure, especially the teeth, with other members of its family.
4. They only have 3 teeth
Video by Ludovic Amevor
The sunfish is truly unique in its eating style! With only three teeth, two in the mouth and one in the throat, they don’t chew their food. They use the throat tooth to crush it until it’s small enough to swallow and digest. Moreover, their small mouth has strong jaws, but they can’t close them properly due to the fusion of certain parts. It is a fascinating adaptation for such an extraordinary fish
5. Sunfish don’t have scales
The sunfish have a peculiar feature: they lack scales. Instead, they have thick, elastic skin covered by a gelatinous mucus that protects them. The thickness of this skin can exceed 7 cm.
6. They also don’t have a swim bladder
The sunfish’s subcutaneous gelatinous layer is crucial for maintaining neutral buoyancy in the sea. This feature allows them to float and move efficiently. Hence, they constantly swim or flap their fins from side to side to stay afloat and control their position in the water.
7. The name Mola mola comes from its resemblance to the stone used in the mills to grind the grain, the “millstone”
Curiously, the sunfish is called in Spanish and French as moonfish (Pez luna and Poisson lune). In Spain, there is a legend that tells us that when fishermen went fishing at night and found some of these fish swimming near the surface, they confused it with the reflection of the moon in the water and since then this fish has been known as moonfish.
8. They like sunbathing!
The sunfish gets its English name from its habit of “sunbathing” at the surface. The sunfish engages in sunbathing, a behavior known as “sunfish basking,” as a strategy to regulate its body temperature. Despite being cold-blooded animals, exposure to the sun helps warm their bodies by absorbing heat through their dark skin. Moreover, this sunbathing ritual aids in parasite removal, as certain cleaner fish approach to feed on parasites present on their skin. It’s a fascinating adaptation that helps them balance their temperature and stay healthy in their vast marine home.
In addition to the help of seabirds and cleaner wrasse, a mola may leap up to 3 m in the air and then splash down hard to shake off the parasites.
9. The dorsal and ventral fins are very elongated and, when extended, it is as long as it is high
In the course of evolution, the caudal fin disappeared and was replaced by a rounded structure that takes the name of “calves,” which is a kind of fan-shaped pseudo-tail
Due to the lack of a proper tail to propel itself forward and the small size of its pectoral fins, the sunfish uses its thin and long dorsal and ventral fins to move.
It is pushed forward by moving both fins from one side to the other simultaneously and in the same direction.
10. Its brain is very small
An individual weighing 200 kg can have a brain weighing very few grams.
11. Its diet is based on different types of gelatinous zooplankton
Although not very nutritious, sunfish consume this food in large quantities to grow and maintain their considerable size. They enjoy eating jellyfish, squid, sponges, crustaceans, and small fish.
12. Female mola mola can lay over 300 million eggs at a time, more than any other vertebrate in the world
13. The sunfish experiences the most extreme growth among vertebrates
At birth, the larvae measure only 2.5 mm and weigh less than a gram. These fish gain almost 1 kg daily until they reach their full size.
From birth to adulthood, they increase their size by more than 60 million times.
The sunfish fry, with large pectoral fins, a caudal fin, and unusual body spines in the adult sunfish, resemble the miniature pufferfish, its close relatives.
Youngsters swim together in banks to protect themselves, but this behavior is abandoned as they grow up, and as adults, they spend most of their time alone.
14. Mola mola can change color
Molas are capable of color changes, particularly when stressed or under attack by a sea lion or other predator. They can turn from light to dark within a matter of moments.
15. Molas really don’t like traveling
The data collected so far shows that the molas do not travel much. Even so, they are not clumsy or lazy fish.
They go up to the surface to sunbathe, get cleaned by cleaner fish, and go down to the deep ocean at least 40 times daily.
Although they may seem clumsy at first glance, they can move as quickly as oceanic sharks to feed or avoid their predators and can even jump out of the water.
16. Threats
Ocean sunfish may live up to ten years in captivity, but the longevity of molas in the wild is still a mystery.
Adults are vulnerable to few natural predators, although they are prey to sea lions, killer whales, and sharks.
Speaking of sharks, sunfish are commonly confused with them since they are often found swimming at shallow depths with their large dorsal fin hovering on the surface. But despite their size, oceanic mola-mola is harmless to humans.
Sometimes, these fish appear trapped in fishing nets.
Another major threat to molas is plastic bags discarded in the water. A floating plastic bag looks like a jellyfish. A mola can absorb it and drown immediately. Or it can clog its interior and starve the fish slowly.
Unfortunately, they are classified as endangered, on the same level as polar bears, cheetahs, and giant pandas.
17. Scuba diving in Bali with Mola
Mola mola in Bali lives in the deep waters between Candidasa and Nusa Penida. They visit cleaning stations when the ocean becomes colder, usually from June to November. Oceanic Sunfish has been spotted occasionally in other areas of Bali and out of the season.
These dive sites are known for the strong currents they can present. Therefore, diving with mola is only possible for experienced and skilled divers. For safety, a previous check dive is always mandatory.
18. Be a responsible diver
In Bali, guidelines have been designed to provide a satisfactory and safe diving experience while ensuring the lowest sustainable impact on the island’s sunfish and manta ray population. The aim of developing the Code of Conduct for Sunfish and Manta Ray interactions is to ensure Sunfish and Manta Ray can settle onto cleaning stations without being disturbed. Once settled, the Sunfish and Manta Ray can remain on station for longer periods, offering better quality interactions for divers.
Would you like to dive with us? The truth is, we are waiting for you!