1) Huge liver
The liver of a shark can comprise up to 30 per cent of its body mass and performs an incredible number of tasks, including keeping it afloat.
2) No reverse gear
Sharks can’t use their fins to paddle, like most other fish. This means that they are unable to swim directly backwards.
3) Familiar eyes
Sharks have eyelids, although they never blink, but they can contract and dilate their pupils, like humans, something no bony fish can do.
4) Power napping
The spiny dogfish uses its spinal cord to co-ordinate swimming, rather than its brain, meaning it can swim while sleeping.
5) Fishy barometer
It is possible sharks may be able to use their lateral line to detect approaching frontal pressure systems and swim deeper to avoid hurricanes.
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