Aug 2020

The Teeny-Tiny Beginnings of The Baby Ocean Sunfish

By Elena Vivaldo

The Ocean Sunfish, also known as the Mola Mola fish among divers; is one of the most mysterious and bizarre looking fish in our oceans. It may not be one the most popular sea creatures, but ask any seasoned diver, and they’re bound to have it on their marine life bucket list.  Now more than ever with the discovery of the baby ocean sunfish.

The Ocean sunfish is the heaviest of all bony fish. And Seeing it in its natural habitat won’t fail to amaze even the most adventurous divers.

Mola mola has no real tail to talk of, and the rest of their body seems like a turtle turned on its side – after a road accident. With its big round eyes and puffed up “cheeks” like it just got its tooth pulled out at the dentist’s, this beaky-looking fish is strange indeed.


Feeding primarily on jellyfish, Mola mola poses virtually no threat to humans, and divers are left spellbound as it gently moves through the water. So getting the chance to dive with them is an unbelievable experience, a rare treat for any passionate diver. And whoever sets eyes on them will ask questions that sound like this: “How did they grow so big”?

I get it. Its massive size and unique body shape will have anybody question the Mola mola’s beginnings as a baby ocean sunfish. But shockingly, very little is known about the sunfish’s lifecycle, especially about the early stages of its life.

Until recently.

Scientists discover baby ocean sunfish

After years of mystery, scientists in Australia, led by Dr Marianne Nyegaard, were finally able to match the DNA of a baby ocean sunfish with the giant bump-head sunfish (Mola alexandrini). One of the three species of Mola.

The difference in size between the giant sunfish and their teeny-tiny babies could not be more dramatic. Measuring around 2mm, the giant sunfish larva grows into a 3-metre long giant (11 ft) weighing more than 2’000 kg (315 stones). Who would have guessed that such a little thing could grow into something so big!

Scuba divers and ocean lovers are simply blown away by this discovery, and by how cute the giant sunfish larva is! They really look like something out of a cartoon.

Baby ocean sunfish

What took so long to identify the giant sunfish larva?

While it is not the first time researchers have found sunfish larvae, they’ve never been able to match them to an adult ocean sunfish. Why? Primarily for two reasons:

  1. Baby Ocean Sunfish look nothing like their adult form

Ocean sunfish larvae look nothing like their adult form. Their baby features disappear in time, leaving no recognizable traits that would point to an obvious match. So there really is no way of telling whether a baby sunfish is a bump-head sunfish or another species of Mola.

  1. Baby Mola mola are rare

Baby ocean sunfish are hard to find, and the few that have been found are kept in museum collections. To preserve this handful of specimens, no genetic analysis was ever possible.

It was only in 2017, after the discovery of a few larvae that Dr Nyegaard set out on a mission to identify them.

Still, to minimise any damage, Dr Nyegaard took a DNA sample from the eyeball of the 2mm-long larval specimen. Imagine that!


Still so many unanswered questions!

The matching of the giant sunfish larva to its adult version is a ground-breaking discovery as to its mysterious beginnings.

But like most things in life, one discovery leads to many more questions. Scientists still need to identify the larvae of the other two species of ocean sunfish (Mola mola and Mola tecta). Plus, it is still unknown where ocean sunfish spawn, how many eggs they hatch, where they live, and why can’t we find more larvae in the ocean.

For the time being, let’s appreciate scientists’ hard work. Without their dedication, we wouldn’t know many natural wonders that surround us.

But in the meantime, do you want to know more cool facts about ocean sunfish and where you can dive with them? Read our intro guide to Mola mola.

On a scale from cute to adorable, how would you rate the baby Mola mola? Have you ever seen one of these extraordinary creatures? Let us know in the comments!


Photo credit(s): Erik van der Goot, pympym, Kerryn Parkinson/Australian Museum, Amy Coghlan, Daniel Botelho.

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Elena Vivaldo

One thing's for sure, I slowly drifted into becoming a PADI instructor.
I took my first breath underwater when I was 10 while on holiday in Turkey, and got my open water certification at 16, in Thailand.

Initially, diving was simply something I enjoyed doing while on holiday, but at some point, I decided to up my game and to make something out of it. I've always loved travelling, and diving gave me the freedom to travel and work at the same time. So I took my first step towards becoming a PADI pro, and I did my divemaster internship in Tenerife. I worked on the island for a few months before heading to India to further hone my diving skills.

Years later, and with many dives under my weight belt, I've had the great opportunity to introduce people to the underwater world and to explore many exciting dive destinations. There is nothing I like more than seeing new dive sites around the world (my weakness).

When not teaching, I continue to share my love for diving by writing about it. As a copywriter, I can blend my diving and writing skills to create insightful content. But more importantly, I've found a way to stay connected to the world beneath the waves even when I'm out of the water.

Diving Qualifications:
- PADI Open Water Scuba Instructor
- PADI Speciality Instructor: deep, wreck, night, enriched air, O2
- EFR Instructor
- Scubapro Level 1 Technician

Dream Diving Destinations:
- Palau
- Cenotes, Mexico
- Galapagos
- Vancouver Island, Canada
- Sardine Run, South Africa
- Mass coral spawning, Great Barrier Reef