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Jul 30, 2018 • 5 min read
The natural world is full of eye-catching mating rituals. Male birds of paradise flash their brightly coloured feathers and perform energetic dances, while red-striped garter snakes roll around in ‘mating balls.’ However, the title of most spectacular mating ritual may well belong to the Australian giant cuttlefish.
Each year from May to August, hundreds of thousands of these alien-like creatures gather along a small stretch of South Australian coastline. They use the millions of colour cells in their skin to put on a dazzling light show. Since this gathering happens just metres from the shoreline, it’s surprisingly easy to witness—just don a good wetsuit to brave the chilly waters.
Chameleons of the Sea
Cuttlefish are exceptionally skilled at altering the pigmentation of their skin to camouflage with their surroundings. Consequently, it’s possible to see the colours rolling across their skin as they shimmer over different environments. They also change their body shapes and even the texture of their skin to mimic sand, rocks, and seaweed on the ocean floor.
Throughout the year, cuttlefish utilize these remarkable powers of disguise to evade detection by predators and prey. However, during mating season, they apply their abilities differently. As males gather around a female, they expand their size by flattening themselves out and elongating their bodies, which can reach lengths of up to 1m and weigh over 5kg.
If that’s not sufficient to assert dominance, these alpha males transform their skins into shimmering opalescent canvases marked with intricate patterns of dots and stripes. These maze-like designs are laced with iridescent blues, pinks, and greens that are stunningly bright. Observing two males competing is truly captivating.
As the competitors circle each other in a slow-motion ballet, waves of shade and colour rapidly pulse across their skins. Once a male establishes himself as the dominant one, he will guard a female until she’s ready to mate while fending off any other potential suitors.
The smaller individuals recognize they can’t win this competition, so they’ve developed a clever technique to approach the action. By altering their coloration to resemble females, they attempt to slip beneath the watchful eye of these larger males and access the waiting females, a strategy that results in approximately one-third of all successful couplings.
With a population density of up to one cuttlefish per square metre in their breeding grounds, they’re impossible to miss. Consequently, this results in a technicolour spectacle unlike anything else on the planet.
South Australia is home to the only known large-scale mating aggregation of cuttlefish globally, but it’s fortunate that these remarkable creatures are present at all…
Back from the Brink
In the late 1990s, commercial fisheries were capturing hundreds of tonnes of the giant cuttlefish annually as bait when they noticed the population beginning to plummet. Even after ceasing the practice, this decline continued until a 2013 survey found only 13,492 cuttlefish left. Scientists still don’t fully understand the reasons behind this drastic fall. Although numbers have since rebounded into the hundreds of thousands, the cause of this resurgence remains just as mysterious.
The life cycle of the cuttlefish spans only 12 to 18 months, and each individual participates in a single breeding season, creating a boom and bust cycle that renders them particularly vulnerable to environmental changes. Nobody knows where they go between spawning and their return to breed, nor why the Spencer Gulf is the only locality in the world where they breed in large numbers, making this population fascinating to scientists and marine enthusiasts alike.
Why Whyalla?
Divers first observed the mass aggregation of cuttlefish in the Upper Spencer Gulf, 20km outside the industrial town of Whyalla, in the 1990s. For years, this phenomenon remained largely unknown outside of this community. Consequently, it’s rare to find more than a handful of people swimming at the two primary snorkelling areas outside the annual Cuttlefest—most of the time, there is no one at all in the water.
Although Whyalla is located on a major highway, it is not a top destination on the Australian tourist trail. The primary attractions include a museum dedicated to the long-defunct shipyards and a lookout that provides panoramic views over the local steelworks and the Flinders Ranges across the Gulf.
Those steelworks serve as Whyalla’s largest employer; thus, when they were placed under administration in 2016, the entire town held its breath as hundreds of jobs vanished. Fortunately, a new owner emerged, and thanks to plans to transform Whyalla into a green energy hub, the town is recovering alongside the resurgence of the cuttlefish population.
Off the Beaten Track: How to Get There
The best spot to observe the cuttlefish aggregation is at Stony Point. From Whyalla, follow the Lincoln Highway north from town. After 10.5km, make a right turn onto Inkerman Road, which transforms into Port Bonython Road. After 20km, you’ll find a dirt road signposted as Cuttlefish Drive to the right. From there, navigate a bumpy 1.5km drive along the fence line of a nearby hydrocarbon processing facility to a basic car park with a shelter and toilet block.
A ramp and bollards lead directly into the ocean, and information placards provide insights about the cuttlefish.
If the wind originates from the east and the water becomes choppy, Black Point is another viable option nearby.
Whyalla is located 385km from South Australia’s capital, Adelaide. However, without a vehicle, the only means to access either site is through an organized tour from Adelaide. If you’re not the best navigator—or swimmer—that’s probably the optimal way to go!
Mornings are the best time for swimming with the cuttlefish, as afternoons can become windy, reducing visibility. Fortunately, the average depth of both breeding areas is 4m, and cuttlefish gather in waters as shallow as half a metre, making them visible in almost all conditions.
Water temperatures may drop as low as 12˚C, so in addition to a snorkel, be sure to wear a wetsuit with at least 5mm thickness (preferably 7mm), along with a hood and gloves, all of which are available for hire in Whyalla.
Embark on this extraordinary experience for a truly off-the-beaten-track adventure.
