Previous: What Do We Know About T Cells and COVID-19 Immunity? | SciShow News
Next: Reinventing the Wheel: 5 Species That Roll



View count:3,114
Last sync:
Deep into the ocean even the slightest glimmer give you away. Which is why some fish have evolved to be so dark that they absorb any light that hits them.

Hosted by: Hank Green

SciShow has a spinoff podcast! It's called SciShow Tangents. Check it out at
Support SciShow by becoming a patron on Patreon:
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever:

Bd_Tmprd, Harrison Mills, Jeffrey Mckishen, James Knight, Christoph Schwanke, Jacob, Matt Curls, Sam Buck, Christopher R Boucher, Eric Jensen, Lehel Kovacs, Adam Brainard, Greg, Ash, Sam Lutfi, Piya Shedden, Scott Satovsky Jr, Charles Southerland, charles george, Alex Hackman, Chris Peters, Kevin Bealer
Looking for SciShow elsewhere on the internet?
*intro music*
Once you drop below about 200 meters deep into the ocean there is almost no sunlight. But hiding in that darkness isn't as easy as you might think. That's because many creatures produce their own light through bioluminescence, which they use to lure in or expose prey. And if you're trying to hide in the deep sea reflecting even the tiniest bit of that light can be a dead giveaway. Which is why some species of fish evolved to absorb almost all of the light that hits them. Making them nearly invisible in the deep sea. As unusual as this might sound to us land creatures, in the deep sea it actually isn't that rare. A study the journal current biology in July 2020 found that 16 species of fish absorb more than 99% of the light that hits them and that some of them are only distantly related. It turns out that in the deep sea being extremely dark is a pretty good way to avoid predators so evolution has pushed a lot of species in that direction. But these fish aren't just ordinary black like a t-shirt or fresh asphalt, these fish absorb so much light that it just completely disappears  into them. Like one species absorbs 99.95% of the light that hits it. And that's not something we see in the everyday world. To find out more about how they do this, the authors examined the skin  from nine of the ultra black fish from their study and they found that the fishes strategy for making themselves so exceptionally dark is both unique and in some ways kinda simple. See there are a few other kinds of species with ultra black coloration like butterflies and spiders, and they get their color from complicated nanostructures that absorb light in a certain way.