Crocodiles sleep with one eye open
Crocodiles can monitor prey while sleeping by keeping an eye open, scientists have discovered.
The reptiles are able to carry out “unilateral eye closure”, researchers in Australia and Germany found out.
This involves keeping one half of the brain open, and the eye attached to it to be on the look out for prey or threats.
The behaviour is common among dolphins and seals, with Dr John Lesku, from La Trobe University describing human’s full-brain sleep as “novel.”
“The value of the research is that we think of our own sleep as ‘normal’ – a behavioural shutdown that is a whole-brain affair,” he said.
“And yet, some birds and aquatic mammals sleep unihemispherically with one eye open. If ultimately crocodilians and other reptiles that have been observed with only one eye closed are likewise sleeping unihemispherically then our whole-brain sleep becomes the evolutionary oddity.”