Critter of the month – Cystisoma, the see-through deep sea shrimp

We ask Jon Copley from the University of Southampton to tell us if he was a marine creature, which one he'd be and why.

Jon -I'm Jon Copley, I'm a Marine Biologist at the University of Southhampton and asking a Marine Biologist to pick a marine critter who they would like to be is actually a really hard question because there are so many different life forms out there and they have such remarkable different adaptations, so it is very hard to choose. But, if I have to pick one critter I think I would like to be an animal called Cystisoma and that's a crustacean that lives in the deep sea and it's a type of animal called an amphipod. And what's unusual about is it's transparent. Its whole body is see-through, every tissue and organ is see through. It's like the invisible man and I think that is one of the most remarkable adaptations that I have come across in the deep sea.

So it lives down to about a thousand meters and that is what we call the twilight zone because some light actually reaches down to about a thousand meters in the clearest ocean water. But below about 200 - 300 meters it is very, very faint. In fact the water looks this incredible, luminous black; it's this deepest blue that you could possibly imagine. Because there is still light though getting down to about a thousand meters it means that animals living down in this twilight zone still cast shadows. So life down there is basically a perpetual game of hide and seek, all the animals are looking for the shadows of their prey above and they are all desperately trying not to cast shadows below them.

And so we get transparent animals, that is one way to avoid casting a shadow is to make your body completely transparent to turn into like the invisible man. And that's what Cystisoma does, these animals are shrimp like animals, they are about 4 inches long. I have held one in my hand when I was down in the Gulf of Mexico. They have a pair of enormous eyes, most of their head, which is about a third of their body is just a pair of eyes. So they are looking upwards, incredibly sensitive eyes looking for the shadow of any of their prey above. Then to make sure they don't cast any shadow they're completely see-through.

That is just remarkable. Think about all your body's organs, what would be required biologically to make all of those see-through and transparent, it's a phenomenal creature.

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Jon Copley, NOC