0:02:50 > 0:02:57.
0:03:03 > 0:03:07Welcome to Science Fiction, where you ask questions about science...
0:03:07 > 0:03:11That we can get our teeth into. Come back here, you. Come here!
0:03:11 > 0:03:14BUD E, what've you got for us?
0:03:14 > 0:03:15HE SNORES
0:03:15 > 0:03:17Oh! Sorry, Chief.
0:03:17 > 0:03:19I was in sleep mode there.
0:03:19 > 0:03:23Today's question comes from Victoria in Pretoria.
0:03:23 > 0:03:25Is it true that sharks don't sleep?
0:03:25 > 0:03:28Sharks have gills on the side of their bodies
0:03:28 > 0:03:31which extracts oxygen from the water. Most species
0:03:31 > 0:03:34stay on the move to keep water flowing through them.
0:03:34 > 0:03:37That means they can't fall asleep like we do.
0:03:37 > 0:03:40I find if you can't sleep, a cup of cocoa
0:03:40 > 0:03:45and counting sheep is your only man. Argh!
0:03:45 > 0:03:48Some scientists believe sharks can shut down parts
0:03:48 > 0:03:52of their brain, which allows them to rest, but still keep moving.
0:03:52 > 0:03:54A bit like me doing this show.
0:03:54 > 0:03:58But while in this semi-conscious state, they're unlikely
0:03:58 > 0:04:02to engage in anything too active, such as hunting, feeding...
0:04:02 > 0:04:05Aerobics, line dancing, volleyball...
0:04:05 > 0:04:09It's hard to tell if a shark's resting as their eyes don't close.
0:04:09 > 0:04:13Well, I've a way of finding out, but I wouldn't recommend it.
0:04:13 > 0:04:18Sharks don't sleep like humans, but they have their own way of resting.
0:04:18 > 0:04:21It doesn't involve pyjamas and hot water bottles.
0:04:21 > 0:04:23So that's just a load of old science fiction.
0:04:23 > 0:04:26# Science fiction. #
0:04:26 > 0:04:31That was a nice, snappy episode there, Dr Knowles.
0:04:31 > 0:04:35We'll be able to get the early bus home now. Catch Corrie.