1At a glance
- Scientific Name
- Mola mola
- Common Name
- Ocean Sunfish
- Max Length
- Up to 3.3 metres (11 feet)
- Max Weight
- Up to 2,300 kg (5,070 pounds)
- Diet
- Primarily jellyfish, salps, small fish, squid
- Habitat
- Temperate and tropical oceans worldwide
- Conservation Status
- Vulnerable (IUCN Red List)
2How the Mola mola lives
Mola mola are highly distinctive fish, often described as a 'swimming head' due to their body shape. Their skeleton is predominantly cartilaginous, which contributes to their immense weight. They propel themselves using large dorsal and anal fins, moving in a sculling motion, while their small pectoral fins are used for stability.
Ocean sunfish spend a significant portion of their time in deeper, colder waters, sometimes diving to depths exceeding 600 metres (2,000 feet) in search of food. They are also frequently observed near the surface, where they are thought to 'sunbathe' to warm their bodies after deep dives, aiding digestion and metabolism. This behaviour is where they derive the 'sunfish' part of their common name.
Despite their size, Mola mola are gentle giants and pose no threat to divers. They are often curious and can be observed at cleaning stations, where smaller fish remove parasites from their skin. Their diet of jellyfish and other gelatinous zooplankton highlights their role in the marine food web, consuming creatures that few other large fish can.
3Mola mola vs. other large marine fish
| Feature | Mola mola (Ocean Sunfish) | Whale Shark | Manta Ray |
|---|---|---|---|
| Classification | Bony Fish (Osteichthyes) | Cartilaginous Fish (Chondrichthyes) | Cartilaginous Fish (Chondrichthyes) |
| Typical Size | Up to 3.3 m (11 ft), 2,300 kg (5,070 lbs) | Up to 18 m (60 ft), 34,000 kg (75,000 lbs) | Up to 7 m (23 ft) wingspan, 3,000 kg (6,600 lbs) |
| Primary Diet | Jellyfish, salps, small fish | Plankton, small fish, krill | Plankton, small crustaceans |
| Locomotion | Sculling with dorsal and anal fins | Side-to-side tail propulsion | Flapping pectoral fins |
| Appearance | Disc-shaped, flattened, no caudal fin | Large, spotted, distinct caudal fin | Diamond-shaped, large cephalic lobes |
4What Mola mola means for your liveaboard trip
Encountering a Mola mola is a bucket-list experience for many divers due to their unique appearance and relatively infrequent sightings. Liveaboards often visit specific dive sites known for Mola mola encounters, particularly at certain times of the year when conditions are optimal.
One of the most famous locations for Mola mola sightings is around Nusa Penida and Nusa Lembongan near Bali, Indonesia. Here, the Mola mola come up from the deep, colder waters to specific cleaning stations, especially between July and October. Liveaboards operating in this region schedule dives specifically to maximise the chances of seeing these incredible fish.
While sightings are never guaranteed, choosing a liveaboard itinerary that focuses on these known Mola mola hotspots during their peak season significantly increases your probability. Divers should be prepared for potentially colder water temperatures at these sites, as Mola mola prefer cooler, nutrient-rich upwellings.
5Key regions for Mola mola encounters
| Region | Key Dive Sites | Peak Season | Typical Water Temp (°C/°F) |
|---|---|---|---|
| Indonesia (Bali) | Crystal Bay, Manta Point (Nusa Penida) | July - October | 20-25°C (68-77°F) |
| Galapagos Islands | Wolf & Darwin Islands (deep water) | June - November | 18-24°C (64-75°F) |
| Malta | Gozo & Comino (open water) | July - September | 23-28°C (73-82°F) |
| South Africa | Cape Peninsula (nearshore) | November - May | 12-18°C (54-64°F) |
| Japan | Izu Peninsula, Okinoshima (Honshu) | August - October | 22-27°C (72-81°F) |
6Common misconceptions
Myth: Mola mola are slow and sluggish swimmers. Fact: While they appear to drift, Mola mola can swim surprisingly fast when necessary, using their powerful dorsal and anal fins for propulsion. Their seemingly leisurely surface behaviour is often for warming.
Myth: They are dangerous to humans. Fact: Mola mola are gentle, plankton-feeding fish that pose absolutely no threat to divers or swimmers. They are often curious but will typically maintain a respectful distance.
Myth: Mola mola are rare in all regions. Fact: While Mola mola are considered elusive in many areas, specific locations and seasons offer a much higher chance of sightings, particularly at known cleaning stations or in areas with consistent upwellings.
Myth: They are 'half-fish' due to their truncated appearance. Fact: The Mola mola's unique shape is due to the lack of a true caudal (tail) fin, which is replaced by a clavus – a rounded, rudder-like structure. They are fully formed fish, just with an unconventional body plan.
FAQ
What is a Mola mola?
A Mola mola, also known as an ocean sunfish, is the world's heaviest known bony fish. It is characterized by its distinctive flattened, disc-like body and large dorsal and anal fins, with no true caudal fin.
Where can I see Mola mola while diving?
Mola mola are most frequently sighted around Nusa Penida in Bali, Indonesia, particularly at sites like Crystal Bay. Other potential locations include the Galapagos Islands, Malta, and parts of Japan during specific seasons.
When is the best time to see Mola mola?
The peak season for Mola mola sightings varies by location. In Bali, Indonesia, the best time is typically from July to October, when they are known to visit cleaning stations in shallower, colder waters.
Are Mola mola dangerous to divers?
No, Mola mola are not dangerous to divers. They are gentle, pelagic fish that feed primarily on jellyfish and other gelatinous zooplankton. They pose no threat to humans.
Why do Mola mola 'sunbathe' near the surface?
It is believed that Mola mola 'sunbathe' near the surface to warm their bodies after prolonged dives into cold, deep waters. This behaviour helps to regulate their body temperature, which aids in digestion and metabolism.
What do Mola mola eat?
Mola mola primarily feed on gelatinous zooplankton, including various species of jellyfish and salps. They also consume small fish, squid, and crustaceans when available.