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When you get deep into the ocean, it seems like the whole rulebook was thrown out when it comes to how animals evolved. One great example of this is the barreleye fish (Macropinna microstoma), which was first discovered in 1939.
Experts don’t know the full range of where it lives, but it has been seen in the North Pacific, living its life between 600 and 800 meters (2000-2600 feet) below the surface. It spends its days sitting motionless on or just above the seafloor, looking for potential prey swimming above.
How can it spot its prey when it is above it, you ask?
Well, you might think that its eyes are positioned at the top of its head, but that is not the case. Instead, this odd fish evolved to have a transparent head and tubular eyes. So, when it wants to look up to find prey, it simply directs its eyes up through its head to the waters above.
As if that weren’t weird enough, its eyes are very green. This green pigment, experts believe, helps to block out any of the remaining light that comes from the sun above, which allows it to detect any bioluminescent glow from creatures in the area. You can see it in action in this video:
Surely the green eyes and transparent head are enough to set this fish apart from anything else you’ve ever seen, or even thought of, but that isn’t the last unusual thing about the barreleye fish.
Its head is not just transparent, but it is also filled with a fluid. This fluid helps to protect the fish from the stings of jellyfish tentacles. Its diet includes small crustations and other animals that are swept up by the tentacles of the jellies, so having this ability is critical.
Unfortunately, on the rare occasion where a barreleye fish is brought up from the depths of the ocean (either to be studied or by accident by fishers), its head tends to collapse due to the dramatic change in pressure. So, to learn more about the fish, researchers primarily rely on unmanned remotely operated subs that can be dispatched into the sea to track them down.
As one of the most unusual animals in the sea, it is always nice when new footage of them is taken so that the experts can learn more, and regular people can enjoy the look of this exotic animal.
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