It’s not just humans who need to hit the sack- just about every living organism needs their beauty rest. Even bacteria and insects have been observed entering a circadian rhythm based on changes in the light. But for many members of the animal kingdom, their sleeping habits aren’t always as cut and dry as we imagine it to be. It may be odd, but it works just fine for them. Below are some of the most bizarre sleeping habits that wild animals have.

1. Dolphins Sleep with One Eye Open

While humans head off into dreamland with both eyes shut, dolphins, for survival reasons, must sleep with only one eye open. This is because dolphins are warm-blooded mammals who need to remain active so they can keep their bodies warm. Shutting half of their brain off allows them to get much-needed rest, while the other half focuses on moving around and looking out for predators. Also, this reduces the risk of dolphins drowning in their sleep because they need to come up for air.

2. Elephants and Giraffes Sleep Standing Up

Elephants and giraffes are often the targets of predators despite their imposing sizes. Because of this, they need to be ready to flee in case one does show up. That’s why they take quick, power naps while standing up, using a special mechanism known as “stay apparatus” which locks their knees in place so they have to rely on their muscles. When they do lie down, it’s so they can enter REM sleep. Elephants will enter REM every three or four days while giraffes will nap for a total of 30 minutes in a day, no longer than five minutes at a time.

3. Walruses Snooze by the Skin of Their Teeth

There are plenty of animals who can go without much sleep for a long time, and walruses can hold out for an impressive 84 hours. While in the water, walruses will sleep in short bursts because they have to periodically come up for air. But on land, they can sleep deeply for up to 19 hours, most likely to make up for all those sleepless nights. So it’s not uncommon to see a walrus get the best of both worlds by digging its huge tusks into an ice float and drift off to sleep with its body submerged in the freezing waters. 

4. Ducks Sleep All in a Row

Talk about getting one’s ducks in a row! Like dolphins and other avians, ducks can engage in unihemispheric sleep which allows them to keep half their brain awake and the other half asleep. Their sleeping position is also pretty strategic: sleeping in a row allows the ducks to keep an eye out for predators. The ducks at both ends will sleep with the outward-facing eye open while the ducks in the middle get to enjoy a full night’s rest. Hopefully, they all take turns guarding each other, otherwise it would be very unfair!

5. Parrotfish Sleep in a Bubble

Parrotfish are already one of the oddest species of fish in the world considering the fact that they munch on coral reef and can change both their colors and sex. As for their night time routines? It is truly the most unique one on this list. When preparing to doze off, parrotfish will encase themselves in a bubble of mucus secreted from special glands in its gills. Scientists believe this reduces their chances of getting eaten by eels and that it protects them from tiny blood-sucking crustaceans called gnathiid isopods.