Australian scientists said on Friday that saltwater crocodiles can rest with their one eye open to watch for prey or threat. According to a research, it was revealed that mammal's half brain could be conscious even if it is asleep.

Saltwater crocodiles are widely found in northern Australia and they weigh approximately more than a tonne and can grow up to seven metres long.

Michael Kelly, lead author of La Trobe University, told reporters, "Birds like to sleep like humans, with both eyes closed, but when they feel threatened they'll have one eye open and they'll orientate that eye towards the threat. And the crocodiles were behaving in this way as well".

The study involved three young saltwater crocodiles, which were placed in different tanks and looked individually for more than around 12 months last year. The study was published in the Journal of Experimental Biology.

Kelly said more research is needed to examine crocodiles' brain waves to check if the mammal also sleeps with half part of their brain closed which is called 'uni-hemispheric sleep'.

The study also concluded that humans' way of sleeping when the brain is totally unconscious is found rare in the animal kingdom.

A few marine animals and birds can control whether both parts of their brain or just one part shut down while they are asleep, with one eye connected to watch for prey or threat.