Thousands of giant Australian cuttlefish have migrated into the upper Spencer Gulf for their annual breeding, and people are flocking to watch the spectacular display.
Each year during the cooler winter months the waters around Point Lowly in South Australia are filled with cuttlefish.
“The whole area around Point Bonython accommodates hundreds of thousands of giant Australian cuttlefish,” South Australian Research and Development Institute’s (SARDI) Dr Michael Steer said.
“They aggregate on that 10-kilometre stretch to breed.”
The rocky seabed provides unique and perfect points for the females to anchor eggs.
“It is the only place in the world where you get those quantities of numbers of cuttlefish,” Dr Steer said.
As part of the breeding process, the males put on a spectacular display of colours and shape-shifting to attract and keep a mate.
Rock stars of the ocean
Due to their short lifespan, expressive behaviour and active sex lives, giant Australian cuttlefish are often referred to as the rock stars of the ocean.
“Because their generations turn over so quickly, you get these booms and busts in the population,” Dr Steer said.
They are known to “live fast and die young”.
Male cuttlefish flash zebra patterns at each other during a turf battle. (Supplied: Ocean Photography Australia)
After numbers plummeted in 2011, counts from the 2016 breeding season revealed a sharp rise.
“It bounced back to our second highest on record,” Dr Steer said.
Preliminary results from this year’s counts are also revealing large populations.
“They are an incredibly fascinating creature,” Dr Steer said.
“They can change their colour in a fraction of a second and change the texture of its skin.”
Young males will even change their appearance to mimic females in a bid to confuse other males and move closer to a mate.
An underwater iridescent display
Apart from using their pigmentation to hide or warn other animals, large males also flash zebra patterns to confront other males.
They will posture up or flatten themselves out to increase their size, Dr Steer said.
Giant Australian cuttlefish are back in large numbers for their annual breeding season off Port Lowly. (Supplied: Ocean Photography Australia)
“The remarkable thing is despite all of the colours these animals are able to display, they are actually colour blind.
“The animals can’t perceive the colours as we perceive them but see different shades of grey.”
Protection zone for ecotourism
Dr Steer said with local tour operators reporting record attendances this year, protection of the area was paramount.
“This is the only place in the world that we know of where cuttlefish aggregate annually with such great predictability,” he said.
“It is an absolutely stunning sight.
“To see this natural phenomenon and engage in conversation about biology, sustainability, ecosystem function and that sort of stuff is really incredible.
“It’s achieving iconic status in South Australia, and for those interested in marine systems and natural history, Whyalla is a great place to go.”