A Fish With a See-Through Head

Inside Professor Pip's cozy little lab, the lamps were dim and a great glass tank of dark, dark water glowed a soft blue-green in the middle of the room.

"Come closer, come closer!" whispered Pip, pressing his paw against the tank. He tugged out his small brass telescope and squinted through it into the water. "You are about to meet — oh my whiskers! — one of the strangest fish on the entire planet."

Mia and Leo pressed their noses to the cold glass. And there it was: a tiny silvery fish floating quietly. But its head was… gone?

"There's no HEAD!" gasped Leo.

"Look closer," Pip said, gently.

Mia leaned in. "Oh! It's… it's like a glass bubble. I can see right through it! And its eyes are green tubes pointing UP!"

"Exactly!" Pip's tail swished with pleasure. "This is the barreleye fish. It lives so deep in the ocean that no sunlight reaches — it's blacker than a closet at midnight down there. So how do you FIND food when you can't see anything?"

He clicked off the lamp. The lab went velvet dark, except for the faint blue glow of the tank. "Look up," Pip said.

Above them, dozens of tiny hanging bits of glitter caught the tank light — like specks of dust drifting downward.

"In the deep sea," Pip whispered, "little bits of food drift down from above, and sometimes they make a tiny bit of light. If you look UP toward the surface, you can see their shadows against the very faintest glow. So the barreleye evolved eyes shaped like little telescopes — pointing straight up through its own see-through head." He tapped the top of his hat. "That's called an adaptation — a change over millions of years that helps an animal survive."

"Oh!" whispered Leo. "It's like the sunroof on Auntie's car! You can look up while you keep driving!"

"Precisely right!" laughed Pip. "A living sunroof. Marvelous, marvelous."

He flicked the lamp back on. The barreleye kept drifting, quiet and serene. "For over a hundred years we only saw these creatures after they were caught in nets — where their glass domes got crushed. This was the first time humans ever watched one alive, swimming free, being itself."

Pip pulled two small hand mirrors from his pocket and passed one to each child. "Now you try. Hold this above your head and look up. Imagine you had eyes there all the time — what secrets of the ceiling would you spot?"