The Australian giant cuttlefish is the largest of the world’s 100 or so species of cuttlefish.

Life span
2-3 years

Statistics
The giant cuttlefish can grow to lengths of 1.5m (5 feet) and weigh nearly 15kg (33 pounds).

Physical description
Giant cuttlefish have sucker-lined appendages growing from the head, eight long and prehensile arms, and two retractile tentacles. Cuttlefish have a highly developed central nervous system and highly developed complex eyes, which focus by changing the shape of the eyeball. Light entering the eye is controlled by the shape of the lid. They may be colour-blind, but they distinguish a vast number of tones. They have thick, internal calcified shells beneath an elongated muscular mantle. This mantle is expanded and contracted to expel water from the mantle cavity through the funnel. The mouth consists of a parrot-like beak, jaws, and a rasping tongue.

Distribution
They inhabit coastal waters from western Australia to Tasmania to as far north as Coffs Harbour.

Diet
The main diet of cuttlefish consists of small fish and crustaceans (such as prawns and crabs and small reef fish). Cuttlefish shoot out two tentacles, which are usually tucked away in pouches under their eyes. Prey is pulled into the powerful suckered arms and then eaten by crushing the animal with their beak.

Behaviour
Giant cuttlefish can crawl, swim or employ jet propulsion in bursts of surprising speed. They are usually solitary, attracted to bright colours, and curious about divers. Cuttlefish have a remarkable facility for changing colour to show aggression, fear or sexual excitement. Under their skin they possess a dense layer of elastic pigment sacs called chromatophores, which are used to change their colour. As camouflage, colour changes are used to match surroundings with extraordinary accuracy. Like all members of the squid family they use jets of ink to confuse attackers. These colourful cephalopods aggregate in their millions along the south Australian coast every autumn. Giant cuttlefish need a hard substrate on which to lay their eggs, so they gather on rocky reefs to breed. The result is one of Australia’s great underwater spectacles. The cuttlefish hover like alien spacecraft, constantly bickering as they bump into one another in the dense gathering. Males duel using an intricate combination of colour and body language, pulsing vivid stripes of blues, purples and greens over their mantles. Groups of up to seven huge males battle with each other using intense blasts of colour until one emerges as the winner. He then turns his attentions to the smaller females, mesmerizing them with another kaleidoscopic display.

Reproduction
Fertilization is internal. Mating takes place when the male places his spermatophore in a pouch under the female's mouth. The capsules burst, releasing sperm into the female's mantle, thus fertilizing the eggs. After mating a female will lay about 200 golfball-size eggs among crevices in the reef, which hatch into miniature adults several months later. These tiny creatures go on to live and develop for two or three years, longer than any other species of cuttlefish, which is perhaps why giant cuttlefish grow to such an immense size.

Conservation status
Until recently the cuttlefish harvest at the spawning grounds near Whyalla, South Australia, was limited. New markets in Asia caused a dramatic increase in commercial fishing beginning in 1996. Public concern resulted in closing the spawning grounds to commercial fishing during 1999 and 2000 in order to conduct research that will aid understanding and protection of the animal. Giant cuttlefish are not listed by the IUCN Red List of Threatened Species.

Best place to see
South Coast of Australia and Tasmania.