BEWARE  - SHARK!

You are a scuba diver swimming back to your boat. 
But the sea is infested with deadly Bull Sharks!

You can make each Bull Shark swim harmlessly past by correctly answering the question. You will then swim 
a bit nearer to your boat. 

If you get the answer wrong, you will be allowed another try. But the more tries you have, the more air you’ll use up in the breathing cylinders on your back. When the gauge (the blue circle) at the bottom of your air cylinders has turned completely to black, that’s all your air gone!

So, let’s hope you know your sharks. 
Your life could depend on it!