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Kate Thomas
Kate Thomas

The Strange Logic of the Strawberry Squid’s Lopsided Eyes

Kate Thomas
Kate Thomas

Our oceans are an endless cornucopia of weirdness. Today, we’d like to introduce you to a cockeyed deep-sea cephalopod called the strawberry squid. Researchers writing in the journal Philosophical Transactions of the Royal Society B say each of the squid’s unusual eyes serves a separate purpose in the black depths of the sea.

Histioteuthis heteropsis (literally “different eyes”) is pink, studded with bioluminescent spots, and quite content to cruise through the “twilight zone” some 650–3300 feet beneath the surface of the ocean. It has one enormous yellow eye and one normal blue eye—as normal as squid eyes get, anyway.

Biologist Kate Thomas of Duke University, lead author on the paper, says she was impressed by the strawberry squid’s strangeness. “You can’t look at one and not wonder what’s going on with them,” she says in the video above.

So she decided to find out. She pulled up 30 years' worth of undersea video recorded by remotely operated vehicles at the Monterey Bay Aquarium Research Institute and scrolled through, watching the squids’ behavior and looking for clues. She analyzed 152 different H. heteropsis sightings and another nine sightings of its cousin, Stigmatoteuthis dofleini.

The onscreen sightings revealed yet another strawberry squid eccentricity: They like to float along upside down, with their heads pointed toward the ocean floor. But this posture, while whimsical, appears to be practical. The head-down orientation aims the squid’s large eye toward the surface—which is where any light might originate. The little blue eye, better suited for spotting bioluminescence, can keep looking downward into the darkness.

Senior author Sönke Johnsen, Thomas's advisor, said the squid's blue eye could only have one job. “There is no way it is able to pick out shapes against the ambient light," he said in a statement. "And once it is looking for bioluminescence, it doesn’t really need to be particularly big, so it can actually shrivel up a little bit over generations. But the eye looking up actually does benefit from getting a bit bigger.”

It’s an ingenious solution to a low-light situation. “Eyes are really expensive to make and maintain,” Thomas added. “You want eyes just big enough to do what you need to do, but you don’t want to have any bigger eyes because then you are just wasting resources.”

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'Angry Badger' Terrorizes Scottish Castle, Forcing Closures 
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Portions of the 16th-century Craignethan Castle in Scotland were shut down last week after a less-than-friendly badger holed up there and refused to leave. Historic Environment Scotland, which manages the site in South Lanarkshire, sent out a tweet last Friday notifying visitors that the property's cellar tunnel would remain closed over the weekend “due to the presence of a very angry badger.” Staff tried to coax it out with cat food and honey, but the badger did what it wanted, and they were unable to move the mammal.

A spokesman for HES told the BBC, "The castle is surrounded by woodland and we believe the badger may have become lost. Staff first spotted some dug-out earth on Wednesday evening, and later spotted the badger on closer inspection."

On Saturday, staff used a GoPro camera to check out the tunnel from a safe distance and learned that the badger had left voluntarily, but not before making a mess. The critter dug through both soil and stonework, according to The Scotsman. The castle, an artillery fortification erected around 1530, is already partly in ruins.

Craignethan Castle in Scotland
Sandy Stevenson, Flickr // CC BY-NC-ND 2.0

Badgers are not typically dangerous, but they can become aggressive if they feel cornered or threatened. They can be seen year-round in Scotland, especially during spring and summer. Earthworms, bird eggs, small mammals, fruit, and roots are among their favorite meals, and they can even be “tempted into your garden by leaving peanuts out—a tasty snack for our striped friends,” the Scottish Wildlife Trust says.

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Big Questions
Why Do Cats Sleep So Much?
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Chloe Effron / iStock

Cats can sleep 16 to 20 hours a day. It’s not always deep sleep. Cats spend a lot of time taking short “cat naps” that build their energy, yet keep them alert enough to jump up the moment they sense danger or excitement. They don't sleep a lot because they’re lazy or bored. Cats sleep so that they’re ready to hunt.

Their genes (geenz) tell them to. Genes are the tiny instructions inside the cells of all living things that make a species look and act certain ways. These instructions get passed down from parents to kids. In the case of cats, their genes tell them to sleep a lot, especially during the day. 

A long time ago, cats weren’t domesticated (Doh-MESS-tih-cay-ted). That means they were wild and didn't live with humans. Cats had to hunt to survive, and they needed a lot of energy for that. Just like lions, tigers, and other wild cats, domesticated cats sleep more during the day so they’ll be ready to hunt at night, especially around sunrise and sunset. Of course, most house cats no longer have to hunt at all. But just in case they do, their genes tell them to nap often so they’ll be ready.

Cats can sleep in some pretty strange places, as you can see in this video

 

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