Cuttlefish
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![The characteristic W-shape of the cuttlefish eye](/Images/godic/202502/10/Cuttlefish_eye5304.jpg")
![Pupil expansion in Sepia officinalis](/Images/godic/202502/10/-Sepia_eyelid_shape.theora.ogv5304.jpg")
![Interacting cuttlefish](/Images/godic/202502/10/Georgia_Aquarium_-_Cuttlefish_Jan_20065304.jpg")
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda, which also includes squid, octopodes, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone. Despite their name, cuttlefish are not fish but molluscs.