Steve Backshall answers your shark questions
Steve Backshall is in the Bahamas filming his brand new series, Deadly Mission Shark.
Is the megalodon still around today?
Sorry to break this to you, but no, the Meg has been gone at least two million years ago and possibly even longer than that.
Why do sharks regrow their teeth?
Sharks have teeth that are kind of on a conveyor belt. As the front ones break out, they're replaced by others that roll forward to take their place. Big shark species might get through 50,000 teeth in a lifetime! Effectively, those teeth are modified scales. They're generated constantly throughout their life, and it's just a really effective way of keeping them sharp and able to cut through food.
How strong is the maximum shark bite?
The highest recorded bite force comes from the bull shark, but almost certainly a big great white is going to have a bigger bite force. They haven't been measured accurately. Their bite force is not as strong as the biggest crocodiles, with a simple reason that they have a flexible cartilage jaw - so when they bite down on something hard, their teeth break out. That's what they're designed to do, whereas a crocodile has a thick, heavy, bony skull and strong, robust teeth that can withstand the immense power generated by their bite.
Why are sharks carnivorous? Why do sharks eat meat?
The simple reason is that, out in the sea, meat is a pretty readily available source of protein. It's quite difficult to get protein from other sources unless you are a filter feeder, who is noshing down on plankton. There is, though, one species of shark, the bonnethead, that's been seen feeding on seagrass and is vegetarian.
How fast can a shark swim?
The fastest shark species is the shortfin mako shark, and it's believed that they can go at least 31 miles an hour - possibly even faster than that.
Can sharks stop swimming?
Many open water sharks - like white tips, great whites, blue sharks - continually swim throughout their lives, but there are other species that will live on the bottom and not spend a huge amount of time swimming. They may have adaptations like spiracles - a little hole behind the eye that they can breathe through. Or they may have a buccal pump, which is something inside the mouth that keeps water churning over their gills, and means sharks can carry on breathing or just lying on the bottom.
How do sharks breathe?
The main way that sharks breathe is using their gills. The gills are filled with tiny little blood vessels which come close to the oxygen in the water as it passes over them, and that oxygen diffuses into the blood and allows them to breathe.
Steve answers MORE of your shark questions
How deep in the ocean can a shark go?
Well, sleeper sharks, six gills and some other species have been recorded as deep down as 4,000 metres (or four kilometres) in depth, but it's probable they go even deeper than that.
Were sharks around with the dinosaurs?
Yes, and long, long before them too. In fact, sharks have been around since before trees, at least 440 million years.
How is plastic pollution affecting sharks?
In lots of different ways. There are some shark species that are accidentally eating plastics or getting entangled in it. Also, some of the filter feeders like manta rays and whale sharks are taking in microplastics as they feed, and that's accumulating in huge amounts in their systems.
What is the smallest species of shark that's around today?
That is probably the dwarf lantern shark, which fully grown is only about 30 centimetres, which is the length of a standard ruler. They pretty much fit in your pocket!
What's the biggest shark alive today?
That's the whale shark. They get to be absolutely enormous. The biggest are as much as 18 metres in length, which is huge. That's like two buses back-to-back! They are, though, completely harmless animals that feed on small fish and plankton
What's the most amount of sharks you've seen at one time?
Well, I've been lucky enough to dive with huge aggregations of things like scallops, hammerheads and silky sharks and there could be several hundred in one shiver. That's the correct word for a shawl of sharks, which is awesome.
Are there venomous sharks?
Yes, there are. In fact, there's one species that we have in British waters called the spurdog, and in front of its dorsal fins they have small spines, which are venomous. That's thought to be a defence mechanism.
Can sharks smell fear?
Absolutely, 100%. It's one of the main reasons why the thing I'm trying to teach all of my young recruits here on Deadly Mission Shark is to be calm and confident. If they're not, then I'm not going to let them in the water with sharks.
If you could be a shark, which would it be?
That's an amazing question. I've never had that before! I think I'd be something like an epaulette shark, which can, if it chooses to, come out of the water and go for a walk. So then I'd be able to go and see my friends on land and I wouldn't have to stay underwater the whole time - I think that's cool.