29 April 2010

The wily ways of the octopus

Christine Marot
The common octopus. Photograph by Karin Schwerm

Not only is the octopus an amazing-looking marine creature, it also happens to be the most intelligent invertebrate (creatures without a backbone) and comes equipped with an enviable array of tools to help it outwit its many predators.

Unlike fish and other marine species, an octopus is unlikely to immediately flee from a predator. Its first line of defence is to lie perfectly still and do its best to blend into its surroundings.

Thanks to a network of pigment cells and muscles, the cephalopod (mollusc) has the ability to instantly mimic the patterns, colours and textures in its surrounding environment. This allows the octopus to hide in plain sight as predators such as sharks and dolphins swim past without spotting it.

If chased, an octopus resorts to its second line of defence, by releasing a squirt of black ink that temporarily obscures a predator’s line of sight and confuses its sense of smell, giving the octopus time to dart away to safety.

The octopus is a rapid swimmer. It uses a simple form of propulsion, squeezing water out of its soft body, to quickly shoot away. Once it has jetted away, the octopus will squeeze its body into the nearest rocky crevice to hide from pursuing predators.

Should the predator continue its attack, the octopus may have to sacrifice a leg to save its life. This is a similar survival tactic to a lizard dropping its tail to distract a predator while it escapes. As in the case of the lizard, the octopus will simply regrow the missing limb.

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