Something Sounds Fishy! Myth Buster’s Blog (1 of 2)

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Incredibly it seems the ocean sunfish has gone viral yet again! I know, I was surprised too! Firstly Boston Man broke the internet with his ideas of catching a ‘baby whale’ (*spoiler, it’s a sunfish!) and now an incredible rant about the “biggest joke played on earth”, again with sunfish as the butt (or should that be swimming head) of the joke! I love a good rant (esp. David Mitchell when he goes off on one), but in the dark days of fake news, there are a few little problems with Scout Burns’ epic tale of “wasted space” that I feel we should explore.


Fishy News Stories…. Time for #FridayFacts!!

Scout has made some pretty big claims about sunfish, the scientists who study them and even the process of evolution itself so I feel it’s time someone stood up for the funny-looking fish and for science itself, so in response today we have a special #FridayFacts edition: The Myth Buster’s Blog!

At the beginning of this viral rant, we are told that sunfish are just “big, dumb idiot[s]” of “the biggest joke played on earth” made when “God must have accidentally dropped [one] while washing dishes one day and shrugged his shoulders” because they have “no purpose… every foot… wasted space”. Of course we cannot agree with this, the ocean sunfish is the brand new kid on the block when we come to looking at species evolutionary speaking! Whereas the fishes as a group first emerged around 500 million years ago, the ocean sunfishes represent cutting edge evolutionary design, having evolved only around 50 million years ago!



Dishes?! More like cutting-edge design

The ocean sunfish showcases a fantastic body honed by selective processes over millions of years, perfectly adapted to a life travelling the world’s oceans. As to their purpose on this planet, this is a bigger question to answer… the meaning of life has been hotly debated for centuries from ancient philosophers to Monty Python (of course the real answer is 42!). But roughly speaking, their “purpose” is the same as the rest of all lifeforms on earth… simply to exist and pass on genes: to feed, grow, breathe, reproduce and die.

The meaning of life and the sunfish life cycle (adult produces offspring as eggs, through larval stages, growing from juvenile to mature adult and the whole cycle starts afresh!)

Of course, having an interest in biology, we want to know a few more details than that! Which is why scientists (myself included) are trying to unravel the complex ecology of the sunfish a little further… but when it comes to scientific understanding, Scout suggests “scientists even debate how [sunfish] move. They have little control… some say they must just push water out of their mouths for direction…They could use their back fin, except… it doesn’t f****** grow. It just continually folds in on itself.”

Now as funny as the idea is of a giant sunfish blowing water to presumably jet backwards (!?!), I am sorry to report that this simply isn’t true. We know how they move and in quite a lot of detail. They use their dorsal and anal fins like a pair of wings to soar through the oceans, undertaking long distance journeys of up to 48km a day! Their funny little caudal fin (known as the clavus) grows of course, and has a vital function (otherwise evolutionarily it would have most likely have been lost!), and is used like a ship’s rudder to steer the fish as it swims.


Similar structures; ships rudder and sunfish clavus

Scout correctly mentioned that sunfish don’t have swim bladders; however it is not true that “that every fish has [one] to make sure it doesn’t just sink to bottom of the ocean… [and sunfish] can barely move to begin with”. Lots of fish do not have swim bladders, for example sharks, as there are other evolutionary designs that can provide lift without the issues of containing air internally (such as problems with rapid descent and ascent). Most fish without swim bladders, including sunfish, have large deposits of fatty lipids in their livers that provide buoyancy = no swim bladder, no problem!


Some of the sunfish’s fellow fishes without swim bladders (left to right: manta ray, great white shark, basking shark, white marlin)

Aside from preventing sinking, Scout also mentions that sunfish seem to “get stuck on top of the water… because without the whole swim bladder thing… the ocean pushes over the [fish]”. This idea again presents a great image, but unfortunately is untrue. The sunfish does not need a swim bladder to remain upright (it’s not a life jacket); they are perfectly capable of swimming upright both at the surface and at depth. Sunfish are often noted “basking” at the surface where they lie on their sides which enables them to increase the rapidity of their heat exchange, to communicate with birds for parasite removal and perhaps simply just to rest, before diving back into the depths (up to 844m deep!)

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Seeking the sun in deep, dark places! Ocean sunfish photos at depth

So that’s all we have time for in this Myth Buster’s Blog edition but I will be posting part 2 next Friday to question the remaining “fishy” facts in the “sunfish are useless animals” rant and of course to provide some illuminating answers! *Spoiler alert, sunfish are awesome super-predators!

If you just can’t wait another week for more sunfish news, please check out my twitter @SunfishResearch or please feel free to ask a question using the comments below 🙂



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