Nov 2016

Amazing Facts of the Mola Mola Ocean Sunfish

By Roya Eshragh

The Mola mola Fish, or Oceanic Sunfish as it is otherwise known, is one of the many prized-sights for divers exploring the waters around Bali. To be honest, I’ve never actually come face to face with one myself. A frustration that has only served to increase my interest in them! After spending hours researching and talking to fellow divers, I don’t mind saying that I’m now something of a Mola boffin. Hopefully you’ll have better look finding them when diving in the beautiful oceans that surround southern Asia. Here is everything you need to know about the Mola mola.


What is a Mola mola fish?

Despite sounding a little bit like an Amazonian rain dance – and despite sounding a lot like a tooth in the human mouth – the Mola mola is the common name given to the Sunshine Ocean Fish. Whichever name you choose to use (FYI: Mola mola is the one commonly used in diving communities) one fact is not open for debate – this is the world’s largest bony fish. The sheer size of the fish means that it is sometimes mistaken for a shark. But in my opinion a better description comes in the form of the German name – “Schwimmender Kopf” – this roughly translates as swimming head.

So now we know what to call it, and a little about what it looks like, but what does Mola mola mean? The word mola is actually Latin for millstone, which, once I looked up what a millstone was, is a surprisingly accurate physical description. Molas belong to the Tetraodontiformes (try saying that three times in a row without stuttering) order along with boxfish, pufferfish, triggerfish, and filefish. Basically it’s the order of the fish weirdos. They belong to the family Molidae which contains four species, all called sunfish of some sort as their common names



The Mola mola size

I mentioned before that this is the largest bony fish in the ocean, it is also the heaviest with the largest recorded Mola weighing in at 2,300 kg (5,071 lbs). To offer some perspective, a mini weighs 642kg. Big, right? Molas have arguably the most extreme size growth of any vertebrate with the potential to grow to more than 60 million times their birth size. They start out as tiny fish larvae more resembling pufferfish than their parental forms. As they grow, they lose their baby spines and form the large, round, laterally flattened, tailless giants we more commonly know them as. They can spawn up to 300 million eggs at a time, more than any other vertebrate, thanks to their large body accommodating all those tiny eggs.


The Mola mola look

Surprisingly, the largest bony fish in the ocean not only has fewer vertebrae than any other fish, its skeleton is also mostly composed of cartilaginous tissues and not bony tissue. The cartilage is lighter than bone, so it allows the fish to reach sizes impractical to others of their class. With only 16 vertebrae, the body is shorter in relation to the size of any fish, giving them a short, truncated look.



Where to find the Mola mola fish?

There are a few great places to dive and swim alongside Mola. But I have whittled the list down to three. Here are my top three places to go find Mola mola fish.

1) Firstly, and this won’t be a shock to any nature lover, come the Galapagos Islands. Diving in this region holds legendary status and should be on any keen divers bucket list.

2) Next comes diving in Nusa Penida which is an island located between Bali and Lombok. Crystal Bay is reportedly your best chance of an encounter as Mola use the coral as a short-stop cleaning station (to get rid of parasites). The best time of year to spot a Mola mola here is from July to October, but sightings are possible year round.

3) I saved the most surprising until last as many people don’t realise that the waters of the Inner Hebrides off Scotland are the home to many Molas. And while you’re there, you might even see a basking shark.

Other places that mola mola fish live include the Alboran Sea off Spain and the Palau Sardinia in Italy.


How does it move?

So you know where to look, and you know what they look like but one key identifier is movement. So how do they move?

To swim, the mola mola fish scull their caudal and anal fins to propel forward, steering with their pseudo tails. They can further refine their movements by squirting a vigorous jet of water out of their mouth or gills. Since sunfish derive their names from their propensity to sunbathe at the surface causing their dorsal fin to break the surface and occasionally be mistaken for that of a shark. However, this behaviour could be more than just a way to warm their large bodies.

Experts believe sunfish can swim as fast as 3.2 km per hour and can travel as far as 26 km in one day, that’s about the same speed as a yellowfin tuna which isn’t bad at all considering its size and mass.


Can you eat Mola mola fish?

Sunfish are not usually an intentionally sought after food fish. They eat mostly jellyfish which there is an abundance of these days. However, M. mola is still listed as Vulnerable on the ICUN Red List due to being frequently caught in drift gillnets. In California, ocean sunfish comprise almost 30% of bycatch in the swordfish fishery. That percentage jumps to almost 90% in the Mediterranean swordfish industry. And we simply don’t know too much about these open ocean giants to paint a clearer picture on their numbers or habits. Adults are usually solitary except during breeding seasons where they are found in groups in certain congregation areas, so finding one is literally like finding a drop in the ocean.


Unique Features

So we established earlier that these giant floating heads are often mistaken for sharks, but the questions of everyone’s lips is surely: “Can they attack like them?” In short, no, they are not an aggressive fish and they more bothered about a three-course jellyfish dinner, not a tough bit of bitter human. They are known as gentle giants so you needn’t feel scared diving alongside these beasts of the ocean. Unlike Jaws, their teeth are fused together in two places and actually look more like a parrots beak. As such, the  inside a mouth they never closes.

So we established that they are not dangerous to humans below the surface, so you presumably assumed they wouldn’t be a danger above the surface either. Well, don’t assume. Mola have been reported to jump into boats and trap people under their massive weight, or at the very least, knock them out for a spell. Which is of course, is not as funny in practice as it is in the abstract.

But don’t fear, the chances of you dying from a sunfish are still much lower than from a refrigerator. Especially if your interaction with these strange looking, enigmatic giants is below the surface. So get out there and go see these sea beasts in their native habitats…just don’t brag to me about it, please.

‘Mola mola’ was written by marine biologist Roya

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Roya Eshragh

Even as a little girl, I was obsessed with the oceans and wanted to become a marine biologist. So, I got into diving in 2011 as an aide for my Master’s research on cephalopod (squid, cuttlefish, octopus, etc) parasites. I completed my PADI Open Water course and continued with the CAUS Scientific Diver course in the cold cold waters around Vancouver BC. When time allowed, I would help with the Howe Sound Research Group of the Vancouver Aquarium monitoring the Sound. I’m sorry to say, but even after all that, I still haven’t quite come to love dry suit diving.

Once I moved to Madagascar as the Science Officer of a marine conservation NGO, I realized just how lovely diving in the tropics could be. There, I completed my DiveMaster and became addicted to daily diving. I had to find a way to continue! So I did my IDC in Bunaken, Indonesia, completing my MSDT course and learning the tricks of the trade on a few inaugural students.

Currently, I am a dive manager/reef ecologist in Sri Lanka and starting up a conservation and education program with my dive shop. Combining my love of the oceans with my love of science, I am thrilled to have found a way to bridge the two and teach others about this incredible ecosystem we still don’t know nearly enough about. There’s still lots more for me to learn, both about diving and about the marine world, and that is the beauty of it all!

PADI Specialty Instructor
CAUS Scientific Diver 1
Master of Science - Zoology

Dream Dive Locations:
Komodo, Indonesia
Silfra, Iceland
Wreck Diving, Lake Michigan

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