If you’ve watched the first episode of Blue Planet, then like many other viewers, you were probably astounded by the fish with a see through head.
The Macropinna microstoma or barreleye fish was first discovered in 1939, biologists have known the eyes were very good at collecting light. But their shape seemed to leave the fish with tunnel vision.
But since then biologists have discovered that the eyes can rotate, allowing the barreleye fish to look forward and upwards through its transparent head.
The barreleye (Macropinna microstoma) is perfectly adapted for life in a pitch black environment of the deep blue sea, where sunlight doesn’t reach. They use their ultra-sensitive tubular eyes to search for the faint silhouettes of prey overhead.
Barreleyes, just a few inches long, are thought to eat small fishes and jellyfish. The green pigments in their eyes may filter out sunlight coming directly from the sea surface, helping the barreleye spot the bioluminescent glow of jellies or other animals directly overhead.
Some viewers attempted to see if they had the same adaptations as the fish.
Did anyone else just try to see if they could look up through their skull like that see-through jelly head fish on #blueplanet ?
— Mat Riley (@thelifeofriley) 5 November 2017
You might be fascinated to know that filming for Blue Planet II took over four years and saw the crew visit 39 countries in the process.