0:00:02 > 0:00:03My name's Steve Backshall.
0:00:03 > 0:00:05Self-confessed shark obsessed.
0:00:06 > 0:00:08This is Shark Bites.
0:00:10 > 0:00:16This time, we meet the supersucker of all sharks - the nurse shark.
0:00:16 > 0:00:20These are experts at shelling seafood
0:00:20 > 0:00:23and have evolved vacuum suction for dealing with their dinner.
0:00:25 > 0:00:28Reaching up to three metres, they're found in tropical reefs where
0:00:28 > 0:00:31there's plenty of prey wandering the sea floor.
0:00:31 > 0:00:37Unlike most sharks, they have a taste for spiny lobsters, crabs
0:00:37 > 0:00:42and even conch, but crustaceans and shellfish come heavily armoured.
0:00:43 > 0:00:47So how does the nurse shark prise out its prey?
0:00:47 > 0:00:51Mexico's coast provides the perfect place to find these sharks.
0:00:56 > 0:00:58Well, this is really impressive.
0:01:00 > 0:01:04Exactly what you'd hope for from a Caribbean reef.
0:01:04 > 0:01:07And the perfect habitat for our shark.
0:01:08 > 0:01:15Just sleeping underneath this overhang here is a nurse shark.
0:01:16 > 0:01:22These sharks have small holes behind their eyes called spiracles that
0:01:22 > 0:01:26they can breathe through, which enables them to lie like this,
0:01:26 > 0:01:28just chilling out in the daytime.
0:01:28 > 0:01:31At night, though, they go out on the reef to hunt.
0:01:33 > 0:01:35Looking at the front of the nose,
0:01:35 > 0:01:38there are two sensory barbels that hang down.
0:01:38 > 0:01:42They use those to taste crustaceans and other animals that are
0:01:42 > 0:01:47down in the sand on the seabed, and it uses those to sense its prey.
0:01:47 > 0:01:49But when it comes to eating,
0:01:49 > 0:01:52it also has to overcome some highly fortified food.
0:01:56 > 0:02:00The nurse shark has an ingenious solution for shelling
0:02:00 > 0:02:02its seafood supper.
0:02:02 > 0:02:06Inside the shark's head, its mouth is actually quite small,
0:02:06 > 0:02:09but this area to the back of the pharynx is really large.
0:02:09 > 0:02:14So by cupping its mouth over a hole or crevice or seashell
0:02:14 > 0:02:16and then expanding its throat,
0:02:16 > 0:02:20it creates vacuum suction which can suck out its prey.
0:02:20 > 0:02:23And all of that happens in about a tenth of a second -
0:02:23 > 0:02:25that's as fast as the blink of a human eye.
0:02:28 > 0:02:35Having found its dinner, it latches on, so there's no escape,
0:02:35 > 0:02:38and hoovers up its prey like an aquatic vacuum cleaner.
0:02:44 > 0:02:46The nurse shark.
0:02:46 > 0:02:49Armed with specialist prey detectors,
0:02:49 > 0:02:53it's an expert at shelling seafood and sucks it down in the blink
0:02:53 > 0:02:58of an eye, making this an exceptional supersucker.