Cuttlefish are marine molluscs in the Sepiida order. They are classified as Cephalopoda, together with squid, octopuses, and nautiluses.
They have three hearts. One heart supplies blood to the body, while the other two supply blood to the gills.
They are the only cephalopods that can change their skin colour to match their environment.
They are excellent swimmers, reaching speeds of up to 20 miles per hour.
Cuttlefish have great vision and can see in both colour and black and white.
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