According to recent findings, crocs resort to half brain sleeping when threatened, since they keep an eye open when a predator is nearby. But they are not the only ones. Some species of birds, dolphins and ground animals are also doing it.
Researchers explained that crocodiles may rest one brain hemisphere at a time in order to remain vigilant and on the lookout with the other. Additionally, crocodiles that were involved in the recent research were more likely to keep an eye open when napping if a human was around.
Moreover, they focused the open eye on the potential predator, researchers noted. John Lesku, lead author of the study, explained that the animals were attentive at humans in a room, and even after humans were gone they still kept an open eye while sleeping. And the eye was gazing into the direction of the potential predators.
Scientists conducted their study in an aquarium. They monitored young crocodiles via infrared cameras while they were at sleep. Study author said that they analyzed only young crocodiles that were no longer than 50 cm because the reptiles are not very cooperative when it comes to human interaction.
“These animals are not particularly amenable to handling; they are a little snippy,”
Dr Lesku of La Trobe University in Australia added.
The team wanted to know whether human presence affected crocodiles’ ways of being asleep. For this purpose, a human was asked to be in the same room where a croc was sleeping. After the human was gone, other crocodiles were introduced in the room. The croc was still half-brain sleeping in the company of its peers.
But the phenomenon is not new in the natural world. Other species resort to “unihemispheric sleep” including dolphins, walruses and other reptiles. These animals used the one-eye-open technique to make sure that they are not left out of the group while dozing.
Some birds also do it to keep an eye on predators. Dr Lesku argued that those species of birds just like crocodiles resort to half brain sleeping when threatened.
But saltwater crocodiles also keep one eye open while taking a nap to make sure that they stick with the group. Researchers believe that this method of sleeping means that the animals are only half asleep.
The team plans to conduct more experiments and measure the crocodiles’ brain waves in both sides of the brain to see if they indeed keep one hemisphere active while the other one is asleep.
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