---
title: 'The Dumbest Animal Alive'
source: 'https://youtube.com/watch?v=gtDKKJq9u30'
video_id: 'gtDKKJq9u30'
date: 2026-07-28
channel: 'Kurzgesagt – In a Nutshell'
---

# The Dumbest Animal Alive

> Source: [The Dumbest Animal Alive](https://youtube.com/watch?v=gtDKKJq9u30)

## Summary

The sunfish, or Mola, is often considered the dumbest creature alive due to its bizarre anatomy, low brain-to-body ratio, and seemingly inefficient lifestyle. Despite these apparent flaws, it thrives in oceans worldwide through unique adaptations like rapid growth, a parasite-cleaning symbiosis with seabirds, and a diet of low-nutrient jellyfish. This video explores the sunfish's paradoxical success and evolutionary genius.

### Key Points

- **Sunfish: The Dumbest Animal?** [00:00] — The sunfish (Mola) is described as the dumbest creature alive, not just in intelligence but also in its comically bad anatomy and survival strategy.
- **Bizarre Anatomy** [00:45] — The sunfish has a giant head, flat circular body, no real tail, and two fins that flap in a goofy wobbling motion. It lacks a swim bladder, using a jelly-like layer for buoyancy.
- **Thick Skin and Parasites** [01:45] — Sunfish have up to 15 cm thick skin, rough and rubbery, but are infested with about 50 species of parasites. Even their parasites have parasites.
- **Sunbathing and Cleaning** [03:02] — Sunfish float on their side at the surface to warm up and allow seabirds to pick parasites off their body, while smaller fish clean the bottom half.
- **Low Brain-to-Body Ratio** [04:41] — A car-sized sunfish has a walnut-sized brain and tiny spine, resulting in one of the lowest brain-to-body ratios in the animal kingdom.
- **Reproduction and Growth** [05:24] — Female sunfish carry more eggs than any other vertebrate (up to 300 million), but 99.999% die. Larvae grow 60 million times in weight to adulthood.
- **Diet and Feeding** [06:37] — Sunfish specialize in eating jellyfish and other low-nutrient prey, using a parrot-like beak and throat teeth to process food. They can dive deep and travel far to graze.
- **Evolutionary Genius** [08:21] — Despite being called dumb, sunfish are highly specialized and resilient, filling a unique ecological niche by being passive and efficient at exploiting low-quality food.

### Conclusion

The sunfish, despite its comical appearance and apparent stupidity, is a marvel of evolution, thriving through specialization in low-nutrient food and parasite-cleaning symbiosis. Its success challenges our assumptions about intelligence and adaptation.

## Transcript

The Sunfish, or Mola, is  the dumbest creature alive. Not just from an intelligence  perspective  – I mean, look at it! It's a being of extremes and  comically bad at being an animal.
Its evolutionary strategy is to be  chunky boys, weaker than their predators, staring into the ocean with empty dumb eyes, eating the least nutritious food possible but growing amazingly fast, getting infested by parasites and dying horribly.
If you presented the sunfish in animal invention  class everybody would be really upset with you. And yet somehow the Mola doesn't just survives but thrives. Like actually how?
The genus of Mola is a fish built wrong, a giant head that evolution lost interest in half way through. Its body is very flat and circular without a real  tail, instead it has a sort of rudder-like stump.
Two fins on the top and bottom give it an ... uhm ... unorthodox swimming style. They propel themselves forward by flapping their fins in a goofy wobbling motion with as little grace as possible.
although when they really try, Mola can  match strong swimmers like salmon or marlins. Sunfish also don’t have a swim bladder, the  gas-filled organ most fish use for buoyancy.
Instead they have a jelly-like layer of  flesh that is 90% water to dive or surface, Most of the time Mola cruises around leisurely. Their teeth are fused into a parrot-like beak that sits in a tiny gaping pout that's open most of the time.
Together with two huge empty eyes, the sunfish has a perpetual derpy face, always looking stunned. Sunfish don’t have proper scales but some of  the thickest skin in the ocean after whales. Up to 15 cm thick, it's rough and rubbery and often covered in mucus​, like armour made from car tyres.
Although most of what it is protecting  is not that great in the first place. Sunfish can become as big and massive as a large car but its organs are collected together in the front of their body, while most of their bulk is oddly textured,
flabby, gelatinous tissue – an animal made from all the worst parts of a steak. This very mid meat is supported by a sort of weird skeleton without ribs or a tailbone and a lot of cartilage.
Their weird bodies are a mobile mini ecosystem,  infested and saturated with around 50 species of parasites Crustaceans, barnacles, various worms and protozoans live on and in their skin, muscles, gills or organs.
They are such a paradise for parasites that even  their parasites have their own smaller parasites! Some Mola are also followed by an entourage of other fish that seek protection, food scraps or feed on their inhabitants.
This awkward situation may be the  root of their most bizarre behavior: Mola frequently swim to the surface  to float on their side like a pancake. They are sunbathing to warm up again from deep cold dives
But they also do it to present their  body to seabirds like albatrosses. The birds start picking the parasites from the Sunfish body – while smaller fish that live near the surface
take care of the bottom half – cleaning them in exchange for a snack. While this is a great adaptation to their parasite infection it sadly often leads to dead  sunfish when they collide with boats.
Since they are still cold and slow from  the deep when they float on the surface, Once Mola reach a certain size most predatory fish seem to avoid them,
probably wrongfully assuming their size means that they could fight back But orcas, sharks and sea lions sometimes  attack and take a bite – usually only to say:
Because for big predators sunfish are watery, not very nutritious, cartilage filled, parasite-ridden jelly donuts. Leaving Molas swimming around with big  chunks missing, looking even more ridiculous.
Sea lions have been observed to skip the whole sunfish and only eat its organs, play with its body like a frisbee and  then leave the rest for scavengers. but we will never know because our  chunky boys are incredibly stupid.
Sunfish have one of the lowest brain  to body ratios in the animal kingdom. A car-sized mola has a walnut-sized  brain and only a tiny spine.
So its mind runs an early alpha version  of intelligence with updates disabled. If you look a sunfish deep in the eyes,  you will mostly see your reflection. Despite or maybe because of their  daftness they are pretty gentle fish
that show no aggression towards other  larger animals and are friendly to humans. Sometimes they even approach divers or boats to  check out what they are and to stare at them derpily. Even if sunfish could get angry, they kind of  lack the tools or temperament to hurt a human.
Adult sunfish are loners that spend most of their lives drifting and wobbling through the ocean solo, Spotting two sunfish making  love is extremely difficult
But we know that their strategy is for 99.999% of their offspring to die.  Female mola carry far more eggs  than any other vertebrate on Earth
Sunfish eggs are tiny and float in the plankton,  where millions are eaten, starve or don't even hatch. The larvae that do hatch are adorable rice grain sized weirdos
covered in little star shaped spines with the derpy facial expression of adult sunfish. All kinds of predators gobble up  these tiny mola by the millions, Luckily sunfish have the most  rapid and extreme growth of any animal
– a larva can increase its weight  60 million times from hatching to adult​. This is the equivalent of a human baby  growing to the weight of an aircraft carrier. and this is why Mola have chosen to  specialize on the dumbest meal available.
The Dumbest Predator vs The Dumbest Prey  The sunfish found a truly  remarkable ecological niche: If your prey is so pathetic that some other predators don’t want to bother with it, you have it all for yourself.
Mola are generalized predators with a focus on small and soft stuff. Their huge eyes can see incredibly  well, especially in dim water, and they can sneak up on small prey  or sift through drifting zooplankton.
Mostly fish larvae, squids, shrimps, mollusks, starfish,  small crustaceans – really any soft critter they can get to. But maybe their favorite meals are  from the jelly kind of sea life,
which really is something since these are almost  entirely water and have almost no calories. So to get any meaningful amount of nutrition  sunfish can mow through swarms of jellyfish,
Without a swim bladder, Mola can dive very deep and surface quickly and freely, giving them a huge range, able to travel dozens of kilometers a  day to graze on the seafloor or reefs,
hunt for jelly in the deep or consume  plankton and algae near the surface. Huge and constantly floating around slurping in high volumes of low nutrient food.
Since they don’t really chew with their beak,  sunfish have found another absurd way to eat: Mola suck in their prey, pull it through their  throat teeth that prevent it from escaping
and maybe move it around and rip it  apart like a slow motion wood chipper. Ok. As much as we are roasting the sunfish  – and don’t worry, it doesn’t understand that we are making fun of it –  actually it is kind of genius.
that are best filled by being passive and bad at everything. And while it is fun to call them dumb  actually they are a highly specialized  
and resilient species, widely spread  throughout the oceans of the world. A marvel of evolution. A truly genius creature. And as the human gazes into the sunfish’s eyes
and wonders how evolution could  produce such an ingenious creature… Sunny suddenly wonders about her own origins. There is a deeper version of her story that nobody told her  – so let’s help her find out.
With the MyHeritage DNA test she can  take a deep dive into her own DNA, discover her family history, and  explore her geographic origins. And for only $29, she decides to go for it!
just a quick swab inside her check,  pop it back in the mail, and that's it! Like taking a journey back through the millennia,
she can now explore her ancestors’  fingerprints etched into her DNA. With Ancient Origins, a new feature by MyHeritage  DNA, Sunny traced her story back 10,000 years
— to find out she’s  descended from Norse Vikings! And there is more: she also discovers thousands  of distant relatives all over the world! makes you wonder if they like Sunfish as much as she does.
This was more than just a DNA test -  it was like a global family reunion! If you are curious about what  your DNA might reveal about you, for just $29. Click the link, or scan the QR code.
Your DNA connects you to every  other human on this planet, and learning about your origins can yield some  truly amazing insights into how you … became you!
Our official Sunfish poster is now available  on our shop – but only while supplies last. This poster also kicks off a brand-new  series of dedicated video posters.
While you’re browsing the shop, check  out our other sciencey products. Thanks for helping this dumb  fish make smart science happen!