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Dolphin Research Center, Grassy Key
Dolphin Research Center, Grassy Key

How Do Dolphins Sleep Without Drowning?

Dolphin Research Center, Grassy Key
Dolphin Research Center, Grassy Key

Having to come to the surface regularly for oxygen makes dolphins great for reliable viewing. But doesn't it sound a little exhausting? As humans understand it, sleep tends to involve a level of unconsciousness that would seem dangerous to aquatic mammals. We reached out to the Dolphin Research Center in Florida to find out how they're able to sleep without drowning.

Senior Education Instructor/Handler Noelle Belden explains that first you have to understand that dolphins are conscious breathers—each breath is an active decision to swim to the surface and open their blowhole, rather than part of a constant "automatic" process like what humans have.

So that explains how they keep from drowning, but their sleep adaptation is more than a matter of holding their breath for a really long time.

Sleep Time

First of all, dolphins don't sleep in one long chunk like humans or other mammals. Instead, they take 15 to 20 minute naps throughout the day and night. But the biggest factor in dolphin sleep is their brain doesn't rest all at once like humans' do. "Scientists have discovered that instead of 'falling asleep' and entering an unconscious state like humans, a dolphin rests one hemisphere of its brain at a time," Belden explains. "So while one hemisphere is resting, the other is still active so that the dolphin can be sure to open its blowhole above the water."

Whichever brain hemisphere is active, the opposite eye will remain open. This is good for both swimming to the surface to breathe and for keeping a look out for predators. As Belden puts it, "Dolphins literally sleep with one eye open."

It's impossible to know what sleeping with just half your brain at a time would feel like, and dolphins can't exactly explain it to us. But Belden says that scientists speculate it might be sort of like daydreaming or meditating.

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holidays
Bleat Along to Classic Holiday Tunes With This Goat Christmas Album
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Feeling a little Grinchy this month? The Sweden branch of ActionAid, an international charity dedicated to fighting global poverty, wants to goat—errr ... goad—you into the Christmas spirit with their animal-focused holiday album: All I Want for Christmas is a Goat.

Fittingly, it features the shriek-filled vocal stylings of a group of festive farm animals bleating out classics like “Jingle Bells,” “Rudolph the Red-Nosed Reindeer,” and “O Come All Ye Faithful.” The recording may sound like a silly novelty release, but there's a serious cause behind it: It’s intended to remind listeners how the animals benefit impoverished communities. Goats can live in arid nations that are too dry for farming, and they provide their owners with milk and wool. In fact, the only thing they can't seem to do is, well, sing. 

You can purchase All I Want for Christmas is a Goat on iTunes and Spotify, or listen to a few songs from its eight-track selection below.

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Animals
If You Want Your Cat to Poop Out More Hairballs, Try Feeding It Beets
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Have you ever wondered if there’s a way to get your cat to poop out its hairballs instead of hacking them up? If so, you’re likely a seasoned cat owner whose tolerance for gross stuff has reached the point of no return. Luckily, there may be an easy way to get your cat to dispose of hairballs in the litter box instead of on your carpet, according to one study.

The paper, published in the Journal of Physiology and Animal Nutrition, followed the diets of 18 mixed-breed short-haired cats over a month. Some cats were fed straight kibble, while others were given helpings of beet pulp along with their regular meals. The researchers suspected that beets, a good source of fiber, would help move any ingested hair through the cats’ digestive systems, thus preventing it from coming back up the way it went in. Following the experiment, they found that the cats with the beet diet did indeed poop more.

The scientists didn’t measure how many hairballs the cats were coughing up during this period, so it's possible that pooping out more of them didn’t stop cats from puking them up at the same rate. But considering hairballs are a matter of digestive health, more regular bowel movements likely reduced the chance that cats would barf them up. The cat body is equipped to process large amounts of hair: According to experts, healthy cats should only be hacking hairballs once or twice a year.

If you find them around your home more frequently than that, it's a good idea to up your cat's fiber intake. Raw beet pulp is just one way to introduce fiber into your pet's diet; certain supplements for cats work just as well and actually contain beet pulp as a fiber source. Stephanie Liff, a veterinarian at Pure Paws Veterinary Care in New York, recommends psyllium powder to her patients. Another option for dealing with hairballs is the vegetable-oil based digestive lubricant Laxatone: According to Dr. Liff, this can "help to move hairballs in the correct direction."

[h/t Discover]

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