409 Dive Log Australasia December 24

OCTOPUS WISE BEYOND WORDS text and photos by John Magee

Blue Ring Octopus, C. lunulata

Eight arms, big brains. Its early evening. The day shift on the reef is winding down and the nocturnal animals are starting to work out their plans for the night ahead. Under a small overhang on the edge of the reef, a female octopus lies dying. Surround ing her are nearly 500 tiny eggs. As the three hearts of the mother take their final beats, the first of the baby octopus hatch out into the reef. These tiny reef octopus belong to the class Cephalopoda. This class includes squid, cuttle fish and octopus amongst other. There are

around 300 species of cephalopod that range from the 2cm Pygmy squid to the 10m long and 500kg Colossal squid, with everything in be tween. Octopus are found in every ocean across the planet and some cephalopod fossils are over 300 million years old. The octopus stands apart from its other counter parts as they have evolved the larger nervous system and a far greater ability to learn. The word cephalopod comes from the Greek ‘Head-Foot’ which makes sense when looking at said nervous system and its general appearance. With over 500 million neurons that are found mainly in the octopus’s arms, the arms can learn and make decisions on their own, whilst being directly at tached to the head, hence the head-foot name. They do this by being able to independently taste, touch and even control their basic motions, all without direct input from the brain. The octo pus has the largest brain to body ratio of any in vertebrate, and this is often used as a measure of intelligence. The larger the ratio, the more the animal has ‘invested’ in intelligence and so is generally smarter. This intelligence allows the octopus to have an advantage over its other ocean counterparts dur ing its life cycle. After hatching and discovering

Octopus eye

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56 DIVE LOG Australasia #409 - December ‘24