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Kate Thomas

The Strange Logic of the Strawberry Squid’s Lopsided Eyes

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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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Animals
7 Fun Facts for World Elephant Day
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Happy World Elephant Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.

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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.

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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit low-frequency sound, inaudible to humans, that warns other elephants. "It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told the Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.

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Human adults and babies often use pointing as a way to nonverbally get a message across, but not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 

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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.

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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.

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If you thought being pregnant for nine months was bad, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herds’ complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.

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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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Animals
Audible Launches 'Audible for Dogs' to Help Pet Parents Calm Their Stressed Canines
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In addition to a mutual love of hamburgers and lazy sunny afternoons in the backyard, dog owners can now share their affinity for audiobooks with their furry friends. As Fast Company reports, Audible has launched Audible for Dogs, a new service designed to keep canines relaxed while their owners are away from home.

Some people play music for lonely dogs, but according to an Audible press release, a 2015 academic study revealed that audiobooks worked better than tunes to calm stressed-out pets. To investigate the phenomenon further, Audible teamed up with Cesar Millan, the dog behaviorist who’s better known as the "Dog Whisperer." Their own research—which they conducted with 100 dogs, in partnership with Millan’s Dog Psychology Center in Santa Clarita, California—found that 76 percent of participating dog owners noticed that audiobooks helped their pets chill out.

Dog owners can play Cesar Millan’s new Guide to Audiobooks for Dogs—which is both written and narrated by Millan—for initiation purposes, along with a curated rotating selection of dog-focused audiobook titles including Trevor Noah’s Born a Crime: Stories from a South African Childhood, performed by Trevor Noah; Jane Austen’s Pride and Prejudice, performed by Rosamund Pike; and W. Bruce Cameron’s A Dog’s Purpose, performed by William Dufris. Each title features a special video introduction by Millan, in which he explains why the book is suited for doggy ears. (Pro tip: According to Audible’s research, dogs prefer narrators of the same gender as their primary owners, and books played at normal volume on an in-home listening device.)

Don’t have an Audible subscription, but want to see if your dog succumbs to the purportedly calming magic of audiobooks? New listeners can listen to one free Audible for Dogs selection with a 30-day membership trial.

[h/t Fast Company]

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