Giant Cuttlefish

Fascinating facts about the Giant Cuttlefish

• At up to 100 cm total length and more than 10.5 kg in weight, the giant cuttlefish is the biggest cuttlefish on Earth.
• A single spawning site off Point Lowly can hold about one cuttlefish per square metre, covering 61 hectares; during May-August the aggregation swells to hundreds of thousands, making it the only known mass cuttlefish-spawning event worldwide.
• These cuttlefish rest 95 % of the day, travelling only 90–550 m in their home range, and yet they channel almost all remaining energy into rapid growth, a strategy more like octopuses than fast-moving squids.
• Males abandon their camouflaged skin to flash bright, rapidly shifting colours when courting, while “sneaker” males mimic females to slip past territorial rivals – a visual arms race that shows how intense competition can reshape mating tactics.
• After a single breeding season the animals die, having shed up to half their body weight while fasting.

At a glance

About the Giant Cuttlefish

The giant cuttlefish (Ascarosepion apama) dominates temperate and subtropical Australian waters, stretching from Brisbane in Queensland to Shark Bay in Western Australia and down to Tasmania. Reaching 50 cm in mantle length and up to 100 cm total, individuals can tip the scales at over 10.5 kg, their eight arms and two feeding tentacles flashing with blue blood and three hearts. Their skin houses three layers of colour-changing cells, chromatophores, iridophores and leucophores, allowing instantaneous, polarized displays that rival any marine light show. They stalk rocky reefs, seagrass beds and muddy flats down to 100 m, resting 95 % of daylight hours in crevices before the brief, frantic burst of activity that marks their mass spawning. During this window they abandon cryptic hues, males dazzling females with rapid bursts of bright colour while females, polyandrous by nature, lay eggs on undersides of rocks, each egg fertilised as it passes a sperm receptacle. A surprising trait lies in their vision: although colourblind, their eyes detect linear polarisation of light, a capability that may let them communicate through the very patterns they project on their skin, a silent dialogue beneath the waves.

Seen on screen

More ocean life to discover

Browse Feravox