Ascarosepion apama, (J. E. Gray, 1849)
The giant cuttlefish (Ascarosepion apama), also known as the Australian giant cuttlefish, is the world's largest cuttlefish species, growing to 50 cm (20 in) in mantle length and up to 100 cm (39 in) in total length (that is, including outstretched tentacles). They can weigh over 10.5 kg (23 lb). Like all cuttlefish species, the giant cuttlefish has eight arms and two feeding tentacles, as well as blue blood and three hearts. Using cells known as chromatophores, the cuttlefish can put on spectacular displays, changing colour in an instant. The giant cuttlefish is native to temperate and subtropical waters of Australia, from Brisbane in Queensland to Shark Bay in Western Australia and Tasmania to the south. It occurs on rocky reefs, seagrass beds, and sand and mud seafloor to a depth of 100 m (330 ft). The genetically distinct population in the Upper Spencer Gulf is the most studied population, and has become a tourist attraction.
The giant cuttlefish is native to temperate and subtropical waters of Australia, from Brisbane in Queensland to Shark Bay in Western Australia and Tasmania to the south. It occurs on rocky reefs, seagrass beds, and sand and mud seafloor to a depth of 100 m (330 ft).
The Australian giant cuttlefish is preyed upon by a variety of marine predators. In South Australia's Spencer Gulf, Indo-Pacific bottlenose dolphins have been observed using a specialized technique to remove the ink and cuttlebone before consuming the cuttlefish.
Long-nosed fur seals (Arctocephalus forsteri) are also known predators, and various cephalopods—including cuttlefish—are taken by yellowtail kingfish (Seriola lalandi).
The predation of cephalopods by yellowtail kingfish has raised ecological concerns in Spencer Gulf, particularly regarding the potential impact of aquaculture escapees on wild species, including the giant Australian cuttlefish and their eggs.
Giant cuttlefish live for one to two years. Breeding takes place with the onset of the southern winter. Males abandon their normal cryptic colouring and set out to dazzle the females by adopting rapidly changing bright colours and striking patterns. Females are polyandrous, and collaborative research indicates the tendency for females to reproduce using male genetic material deposited in spermatangia more favorably than in sperm receptacles directly. Females then attach their eggs to the undersides of rocks in caves or crevices, where they hatch within three to five months. A. apama is semelparous, and death follows shortly after a single mating cycle and laying of eggs that will spawn the next generation. A. apama has poor anaerobic capability compared to most aquatic invertebrates and a lack of food leads to catabolism.
In 2009 the species was listed as "near threatened" on the IUCN Red List of Threatened Species due to an observed declining trend at that time.
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