spent resting and hiding in crevices from predators. The exception to this behavioral routine is the mass spawning aggregation, where cuttlefish are far more active during the days or weeks that they spend there. Predators The Australian giant cuttlefish is eaten by Indo-Pacific bottlenose dolphins, which have been observed (in South Australia's Spencer Gulf) to have developed a technique for removing the ink and cuttlebone from a cuttlefish before eating it. They are also eaten by Long-nosed fur seals. Yellowtail kingfish are also known to eat cephalopods. This has raised concerns about Yellowtail kingfish escapees from commercial fish farms impacting other species in Spencer Gulf including eating emergent Giant Australian cuttlefish or their eggs. Upper Spencer Gulf population Unpublished scientific data indicated that there are several genetically-distinct populations of giant cuttlefish living in Australian waters. Discovered by divers in the late 1990s, the upper Spencer Gulf population is the best studied, largely because it is the world's only known mass cuttlefish spawning aggregation. It has also become a popular ecotourism attraction for divers and snorkelers. Hundreds of thousands of giant cuttlefish gather on subtidal reefs around Point Lowly near Whyalla between May and August. While outside of the breeding season, the sex ratio is one to one, Spencer Gulf males outnumber females by up to 11 to one in the spawning aggregation. If this is due to fewer females taking part or to males breeding for a longer period of time than females is not known. With densities of , covering about , the sheer numbers of giant cuttlefish make this breeding aggregation unique in the world. As the cuttlefish are oblivious to divers while spawning, they are now a major regional tourist attraction for divers from around the world. Professor Roger Hanlon of the Woods Hole Oceanographic Institution has called the breeding aggregation "the premier marine attraction on the planet." The upper Spencer Gulf population displays two alternative lifecycles in both sexes (growth pattern polymorphism). The first involves rapid growth with maturity reached in seven to eight months with small adults returning to spawn in the first year. The second involves slow growth with maturity reached in two years, with large adults returning to spawn in the second year. The upper Spencer Gulf population displays reproductive behaviours unique to this population, possibly as a result of the high spawning densities. Large males defend females and egg-laying sites, while small