About the Giant Cuttlefish near Whyalla

Whyalla Diving Services

Upper Spencer Gulf Cuttlefish

Every year, for a few months between May and August, Giant Australian Cuttlefish (Sepia Apama) arrive and congregate in a patch of shallow water on the rocky coastline between Fitzgerald Bay and False Bay just 30min out of Whyalla.

This is the only known gathering of large numbers of cuttlefish, and the results are a unique spectacle not replicated anywhere else.

It’s not known how far they migrate, or why they choose that particular area, but they have appeared reliably every year, in tens of thousands, along the same few miles of coast.

The female and male cuttlefish mate head to head. The male passes a sperm package to the female which she stores under her mantle. She mates with lots of males and when she is ready to produce her eggs, one by one, she carefully selects from the collected sperm packets and uses them to fertilise her eggs. The eggs, which she glues to the underside of the rocky ledges in the area, hatch a couple of months later. The males can only reproduce once and the females die not long after.

Amazing cuttlefish facts

These amazing ‘chameleons of the sea’ are one of the largest species of cuttlefish found in the world; and can reach up to 60cm in length and can weigh up to 5kg.

Diving with the giant cuttlefish can feel very otherworldly. The strange facts that make the cuttlefish so different are:

  • ​Cuttlefish have three hearts and green blood
  • according to studies they are capable of counting
  • Cuttlefish can perceive light polarization, have no blind spots and can see 360 degree
  • They can instantly change colour and shape to match their surroundings
  • Their lifespan is only 1 – 2 years & only one breeding cycle.

​Cuttlefish have the ability to swim in different manners. When in danger, the cuttlefish suck water into their body cavity and expel it through a funnel , resulting in backward propulsion. The other method of swimming involves gentle rippling by their side fins. This is the method of movement when there is no threat of danger.

Cuttlefish also possess the ability to fill their cavities with small amounts of gas, allowing for altered buoyancy.

Defence & Diet

The Giant Australian Cuttlefish shoots a cloud of black ink when threatened or attacked. The ink is not poisonous and acts solely as a decoy device to confuse the predator and allow for a hasty escape.

An alternate defence mechanism is its ability to camouflage itself by altering its colour, texture and shape to imitate seaweed, sand beds and rocky outcrops. This ‘chameleon’ ability also assists the creature in capturing its own prey.

The staple diet of the Australian Giant Cuttlefish consists of crustaceans such as prawns and crabs and small fish such as reef fish and Tommy Roughs. The prey is caught by two powerful tentacles which shoot out from beneath the creatures eyes. The prey is then pulled toward the animal’s strong beak and crushed.

Giant Australian Cuttlefish aggregation at Point Lowly – with thanks from OKY UNDERWATER

Whyalla Diving Services

33B Playford Ave, 5600 Whyalla, South Australia

May - August (cuttlefish season)
Mon to Fri | 9am - 6pm
Sat & Sun | 8am - 6pm

Sep - April
Mon to Fri | 4pm - 6pm
Sat & Sun | 9am - 12am

phone 0419 174 799
*during shop times
email whyalladiveshop@gmail.com

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