0:00:02 > 0:00:03My name's Steve Backshall.
0:00:03 > 0:00:06Self-confessed shark-obsessed.
0:00:06 > 0:00:08This is Shark Bites.
0:00:10 > 0:00:15Not many would argue that this is the most sinister shark in our seas.
0:00:16 > 0:00:18The ragged tooth shark.
0:00:18 > 0:00:22It may be slow, stocky, serene,
0:00:22 > 0:00:26but its mouth is literally overflowing with terrifying teeth.
0:00:28 > 0:00:30They can measure over three metres in length
0:00:30 > 0:00:35and spend their days hidden away in coral caves...
0:00:35 > 0:00:36..or surveying the seas.
0:00:38 > 0:00:41So, why does such a seemingly calm
0:00:41 > 0:00:45and placid shark need such gnarly gnashers?
0:00:45 > 0:00:48South Africa's Indian Ocean coast is the perfect place to get
0:00:48 > 0:00:50a closer look.
0:00:53 > 0:00:55This is the time of day that we've been waiting for.
0:00:55 > 0:00:58It's dusk, the sun is just starting to go down, and this is when things
0:00:58 > 0:01:01underwater get really interesting, particularly with sharks.
0:01:01 > 0:01:04A shark that during the day has been slow-moving, passive,
0:01:04 > 0:01:09almost lazy, can all of a sudden turn into a fast, fearsome,
0:01:09 > 0:01:12and perhaps quite frightening animal, with one thing on its mind -
0:01:12 > 0:01:14hunting.
0:01:16 > 0:01:19And it wasn't long before the sun had set
0:01:19 > 0:01:22and we lost all natural light.
0:01:22 > 0:01:24It's a bit spooky, really.
0:01:29 > 0:01:32There's an incredible amount of life down here.
0:01:32 > 0:01:34There!
0:01:37 > 0:01:39A ragged tooth shark.
0:01:41 > 0:01:44Which definitely lives up to its name.
0:01:45 > 0:01:48Their teeth almost seem to spill out of their mouths.
0:01:52 > 0:01:55They have nearly 100 needle-sharp active teeth
0:01:55 > 0:02:00that are angled backwards, and these form a flawless fish trap.
0:02:02 > 0:02:06Menacing, maybe, but they're a perfect predatory tool.
0:02:09 > 0:02:13And it's not just the adults that have these fearsome fangs.
0:02:14 > 0:02:17Unborn babies have them, too.
0:02:17 > 0:02:19And not only that, but they use them...
0:02:19 > 0:02:21on each other.
0:02:22 > 0:02:27Pregnant females will only ever give birth to a maximum of two young.
0:02:27 > 0:02:31So, the strongest will eat their brothers and sisters
0:02:31 > 0:02:34while still inside their mother's womb,
0:02:34 > 0:02:37making sure that they get a chance to survive.
0:02:39 > 0:02:43Making them pretty remarkable fish, even before they're born.
0:02:45 > 0:02:50The ragged tooth shark, with their terrifying teeth,
0:02:50 > 0:02:52cannibalistic character,
0:02:52 > 0:02:53and killer instincts,
0:02:53 > 0:02:57surely make this the most sinister shark in our seas.