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This is all that most people ever see of an exceptional animal called the Cuttlefish!

Common to many beaches is this white Cuttlefish bone. The name bone is misleading, as it has more in common with the shells of marine snails than it does with the bones in our body. The Cuttlefish uses its bone to maintain its buoyancy and therefore the depth that it swims. The bone is full of tiny spaces that the cuttlefish can fill with either air or water.  Adding more water causes it to sink while replacing water with air causes it to rise. Using this clever balancing act, the Cuttlefish maintains its depth in the water.

People have collected and used the Cuttlefish bone for centuries. It has been ground up and used as an antacid medicine, or used as a polishing powder by jewellers, or added as an abrasive to toothpaste. Its more commonly given to birds to eat or sharpen their beaks.

The Cuttlefish, a relative of squid and octopus, has a flat squat body with eight arms and two longer flatter tentacles.  The Australian Giant Cuttlefish (Sepia apama) is the largest cuttlefish in the world and is found only around the southern Australian coast from Brisbane around to Ningaloo in Western Australia. As the name suggests these animals are huge with males a growing to 1 metre in length with a cuttlefish bone 50 centimetres long. They can weigh over 10 kilograms. Females are smaller than males.

The list of unusual attributes of a cuttlefish makes it an animal worthy of note. Even though it is colourblind it can change the colour of its skin to match the surrounding seaweed, sand or reef (see video below). Cuttlefish can also create lumps and flaps on its skin to aid its camouflage. Its eye has a large W shaped pupil and focuses by changing the shape of its eye. It has three hearts which pump clear blood that turns blue-green on contact with the air. Its tentacles are attached to its head, not its body. It can swim along lazily using its side fins or jet away very rapidly to avoid danger. It lives a short life ending in mating then death. And of course, there is that easily recognisable Cuttlefish bone.

Watch this amazing video of a Cuttlefish changing colours!!!

If you would like to learn more about the amazing Cuttlefish, and when it is appropriate to join us on a snorkel and view them in person please do not hesitate to call The Dolphin Research Institute on (03) 5979 7100 or email our Education Director Mandy Robertson on

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