How many animals can sleep standing up?

Thursday 21st October 2010
Submitted by Vandana Gupta
ANON

To pull off this trick, you need legs that can be aligned vertically, so you don’t need to use muscular effort to keep them in place. You also need knees that ‘lock’ in place. Sleeping upright is advantageous for large animals because they would be slow to lumber to their feet if attacked. For smaller animals the reduction in leg springiness outweighs this benefit. Horses, zebras and elephants sleep standing up. Cows can too, but mostly choose to lie down. Some birds also sleep standing up. Flamingos live on caustic salt flats, where there’s nowhere they can sit down. Many birds roost in trees at night using an arrangement of their leg tendons that causes their body weight to pull the claw shut around the branch. Whether this counts as standing up is a matter of semantics.

GOT A QUESTION?

Scratching your head over a burning scientific conundrum? submit your question and we'll get our esteemed panel of experts to answer it for you.

 

Could humans evolve again from apes if we went extinct?
previous qanda Article
What happens when galaxies collide?
next qanda Article
Q&A Tabs

Phlegm is the mucous secretion of the respiratory passages. The cilia cells that line these passages are continually driving the phlegm upward to the throat, where it triggers the swallow reflex...

Humans looked essentially the same as they do today 10,000 years ago, with minor differences in height and build
due to differences in diet and lifestyle. But in the next 10 millennia, we...

Lobsters and other shellfish have harmful bacteria naturally present in their flesh. Once the lobster is dead, these bacteria can rapidly multiply and release toxins that may not be destroyed by...

Yes, vehicles create a region of relatively low-pressure air behind them, and it is indeed possible to reduce fuel consumption by getting into this ‘slip-stream’. According to research...

Astronomer Fred Hoyle was the first to point out that if you could drive a car upwards at 95km/h (60mph), it would only take about an hour to get into space. To get to the Moon would take a little...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...