70 years of helping people to care for our ocean

 By: Ann Kunz

Each year during the 3rd week of June we take time to highlight some of the most curious and clever invertebrates inhabiting the oceans  – the cephalopods.

Cephalopods, which include the octopus, squid, cuttlefish and nautilus, are molluscs with long tentacles, a large head, a pair of large eyes, and a sharp beak.  It is well documented that cephalopods have the most highly developed nervous system of all invertebrates.

Despite its name, the cuttlefish is not a fish but a cephalopod.  Although perhaps not as well-known as its cousin the octopus, these amazing animals can control their own buoyancy by regulating the amount of gas in the chambers of their inner shell.  

Cuttlefish have eight arms and two tentacles and pupils which are W-shaped in bright sunlight. Their pupils remain circular under dark conditions.

Perhaps you have come across the internal shell of a cuttlefish which we commonly refer to as a “cuttle bone” whilst walking along the shoreline.

Next time you are on the beach and come across a “cuttle bone” perhaps take a moment to marvel at this incredible structure which is capable of regulating buoyancy by controlling gas exchange (sodium & chloride ions) within the tiny chambers of the `bone’. 

More information on cephalopods.