What does a fish have in common with the world’s most popular sailboat and one of Japan’s most popular video games? A ton. Meet the ocean sunfish, the world’s largest bony fish.

These massive fish start out as one in 300,000,000! Female sunfish lay the most eggs of any animal on the planet, and sunfish start out as the size of the head of a pin, and become over ten feet long, and almost 5,000 pounds, which is over the weight of a pickup truck. Fortunately, these fish are known to be gentle giants, and even swim next to swimmers!

A cute baby sunfish that will grow to be millions of times this weight. Image via Cool Green Science.
A cute baby sunfish that will grow to be millions of times this weight. Image via Cool Green Science.

They can live for decades, and can grow at a rate of almost 2 pounds per day. What kind of diet can sustain this growth? After all, these fish grow over 600,000,000 times their size at birth! It turns out, that their diet consists almost entirely of jellyfish, which they eat with teeth that are fused together in an extremely bizarre manner, while swimming several miles on any given day in a ceaseless quest for food. However, they never grow a normal tail as they grow older. In their adolescent stage, they swim in schools, but they spend most of their adult life alone. In fact, their Latin name, mola mola comes from the word millstone, and describes its round shape. But what about their English name? Why are they named sunfish? These fish are known to sunbathe for hours on end towards the top of the water, and actually have a symbiotic relationship with seabirds. These fish have had 50 species of bacteria found on their bodies, and while they are bathing at the top of the water, birds peck away at these parasites, and the fish get cleaned. These fish have interesting names in other languages as well: their German name means swimming head, their Polish name means head alone, and their Chinese name is toppled wheel fish.

On 13th October 1998, staff of the Australian Museum were called to examine an Ocean Sunfish, Mola mola, that was found stuck on the bulbous bow of the cement carrier, MV Goliath, as it tied up to the wharf in Sydney. The huge fish, which weighed approximately 1400 kg was removed from the bow of the ship by the Sydney Waterways Authority.
On 13th October 1998, staff of the Australian Museum were called to examine an Ocean Sunfish, Mola mola, that was found stuck on the bulbous bow of the cement carrier, MV Goliath, as it tied up to the wharf in Sydney.
The huge fish, which weighed approximately 1400 kg was removed from the bow of the ship by the Sydney Waterways Authority.

However, it is not all fun and games for these fish. Sea lions have been known to not only feast on these fish, but to also rip their fins off and use them like frisbees. However, people don’t eat them since their skin has a sandpaper-like texture, and their flesh is mostly made up of cartilage. In fact, it is bad luck to eat a sunfish according to Polynesians, who consider these fish to be the king of the mackerel. They believe that if humans eat a sunfish, they will prevent mackerel from returning in large numbers.  

Sunfish vs. sea lion. Image via Daily Mail.
Sunfish vs. sea lion. Image via Daily Mail.

These fish go back almost 55 million years ago, and their earliest relatives were actually a section of pufferfish. However, they have never developed a normal fish body, and they steer via a rudder-like contraption, which helps to explain why there is a sailboat named after these amazing fish!

A regata of sunfish. Image via Federvela.
A regata of sunfish. Image via Federvela.

If finding these massive fish underwater isn’t enough for you, you can always adopt one yourself, buy a Sunfish boat (which is ironically smaller than the fish themselves), or grow your own in video game form!

An adult sunfish. Image via Daily Mail.
An adult sunfish. Image via Daily Mail.

If you do encounter one of these gentle giants and can’t keep calm, you won’t be alone.

For more profiles in nature, from a deadly octopus to a $300,000 fish to a fish named after Obama to a truly living “living fossil,” read here!

 

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