Tiptoeing around them would be useless, as crocodiles keep an eye out for threats during sleep, showing a remarkable ability of engaging in uni-hemispheric sleep.
- Researchers study saltwater crocodiles that were between 16-20 inches in length
- When in the presence of a human or a baby croc, the crocodiles kept one eye open for supervision
- This proved that crocodiles can engage in uni-hemispheric sleep (one half of the brain sleeps, the other stays awake)
Uni-hemispheric sleep is a natural practice which deems one half of the brain asleep, while the other is still active. It occurs in dolphins, seals, walruses, some species of birds, and now it’s been found to happen for the fearsome reptiles. Crocodiles do have one more trait to deem them exceptional predators.
A team of researchers from La Trobe University, in Australia, have sought to confirm the legends. There has been much debate, and multiple suggestions, but have not been met with any scientific evidence. However, their study managed to observe and prove the assumptions right.
The scientists took several young saltwater crocodiles, that were just between 16 to 20 inches long, and placed them in custom-made aquariums. They were carefully examined day and night, with infrared cameras to track their sleeping habits and behavior. And, indeed, they managed to prove the legends to be true.
According to John Lesku, who participated in the study, they had a human sitting near the tank for 10 minutes. During that time, one eye of the crocodiles was opened and watching the potential threat (or prey) with great care. The other half of the reptile’s brain, however, was fast asleep.
The same protective gesture was witnessed when they introduced a baby crocodile into the tank.
This has proven the exceptional quality of crocs of engaging in uni-hemispheric sleep. Their study is a confirmation of an earlier research conducted at the Max Planck Institute of Ornithology. The previous observational study concluded that while crocodiles can opt for sleeping with both eyes closed, they commonly choose to keep one open.
The researchers believe that the uni-hemispheric sleep is the product of evolution, inherited by a shared ancestors between birds and crocodiles. Both types of animals are considered to be the only two left behind with ancestors tracing as far back as the dinosaurs. In fact, their species were among the few surviving the disastrous events that led to their extinction.
Humans and land mammals, on the other hand, remain with brains that shut down during sleep. The only mammals that are considered exceptions so far are dolphins.
However, if species such as birds and reptiles, who have a long heritage that traces so far back, sleep with one eye open, it means that humans and mammals might just be the odd ones. Our bi-hemispheric sleep could reportedly be an evolutionary oddity.
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