Giant Australian cuttlefish

How it lives

Giant Australian cuttlefish live about one to two years. They breed once, in the southern winter, and then die. Females lay eggs under rocks and in caves or crevices, and the eggs hatch after about three to five months. Adults usually gather in small groups to mate, but at Point Lowly they form one very large aggregation each winter, from about May to August.

Where it goes

Giant Australian cuttlefish live on rocky reef, seagrass and sand in temperate southern Australian water, to about 100 m deep. They are not known for long migrations, but they gather in winter to breed. At Point Lowly in the Upper Spencer Gulf, adults meet on a shallow reef along about 8 km of coast. After the eggs hatch in spring, the young spend summer and autumn growing in deeper water.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

In the Upper Spencer Gulf, South Australia, divers count the breeding aggregation each year. Counts ranged from about 13,500 in 2013 to about 247,000 in 2020, and 63,000 in 2025. In 2026 the count was 1,811, the lowest on record and a fall of about 97 percent. Only 440 eggs were found along the 8 km of coast. A harmful algal bloom is the main suspected cause and is being investigated. Scientists note that the population recovered within two years after 2013. The IUCN listed the species as Near Threatened in 2009. I did not read comparable counts for other parts of its range, from Queensland to Western Australia and Tasmania.