A small group of giant cuttlefish where we settled at the beginning of the dive
Over the past few months, Australian giant cuttlefish (Sepia apama)—the largest of their kind in the world—have abandoned their normally isolated and solitary lives to gather in their tens of thousands in the shallow waters of the upper Spencer Gulf. They’re here for one reason, and one reason only: to display their elaborate costumes and dance prowess at what is the only mass spawning aggregation of cuttlefish on our planet.
It’s not known how far these intelligent cephalopods migrate or why they choose this particular location, but each year, without fail, they arrive along the same small stretch of coastline. While we’d like to think they’re here for love—it’s purely about perpetuating their species—it’s magical nonetheless. As we descend into the shallow, icy waters at Point Lowly, a rocky coastline between Fitzgerald Bay and False Bay just 30 minutes from Whyalla in South Australia, we begin to realize that this is no ordinary dive. Levitating above the surging seagrass meadows, thousands of giant cuttlefish linger.
Cuttlefish dance the tango
Not knowing where to point our cameras, we decide to settle by a small group, hoping to capture the elaborate spectacle that continues to fascinate scientists and divers alike. It’s not long before the tango begins, as an entourage of potential suitors shadow the females’ every move—all on high alert for the brief opportunity to mate. Yet, with males believed to outnumber females by eleven to one, how does she choose? Weighing in at up to 22lbs and more than three feet in length, she has many handsome fellows to choose from.
Like intelligent aliens, neurally organized cells under their skin trigger a kaleidoscopic display of patterns, colors and textures, indicating their romantic intentions. Hypnotically strobing, their costume changes are frequent and galactic. A large bull male snuggles in close, guarding the female with all his muscle—arms outstretched, strobing and looking for a sign from her. Smaller males use the art of mimicry and attempt to disguise themselves as female, hiding their male fourth arm (hectocotylus) and artfully moving in closer. These stealthy smaller males are sneaky and often successful at stealing her heart—right out from under the dominant bull male’s nose.
An intelligent alien in close up
With the males quarreling among themselves and competing for her attention, we had expected it would be the strongest of males that decided who got to mate. Surprisingly, however, it’s the female that ultimately decides: To warn off male suitors she doesn’t find charming, she displays a white horizontal stripe on the side of her body, pulsing it momentarily. This behavior continues until a more pleasing suitor approaches, when she then turns off the signal and instead welcomes his advances. At her request, the pair meet head-to-head in a fiery embrace, as he passes her his sperm package, which she stores in a small opening under her mantle—a process that can take as long as seven minutes.
Female giant cuttlefish are polyandrous, so she will mate with lots of males today—perhaps not surprising, as she does have three hearts! She delicately collects and stores their sperm packages until she’s ready to produce her eggs, when she then carefully selects one package to fertilize the sperm. The underside of a rocky ledge is the perfect place to secure her precious tear-shaped parcels, where in a few months they will hatch—while she herself dies.
Giant cuttlefish are semelparous, meaning they only have one reproductive event in their lifetime. Her life is therefore fleeting—less than two years. Sadly, as each male fulfills his lifelong mission of mating with as many females as possible, he will also die. As the South Australian spring emerges in September, their eggs will finally hatch, surrendering thousands of juvenile giant cuttlefish to the green seas. Like their parents, they will leave the breeding grounds, albeit to return a year or so later to the same stage on which they were born—to dance the same dance their parents did.
Two small cuttlefish mate head-to-head, inconspicuously blending into their grassy surroundings
A large bull male displays his elaborate costume
While the aggregation itself was only discovered in the late 1990s, it’s not really known how long dense gatherings like this have been taking place, but with the earliest fossils of cuttlefish dating back to the Cretaceous period 145.5 to 66 million years ago, you do the math.
In all our years of diving, we’ve never seen such vast numbers of a single species anywhere in the world, but for the cuttlefish, it hasn’t always been that way. Commercial fishing saw giant cuttlefish populations here diminish from around 180,000 in 1999 to critically low levels of just over 13,000 in 2013. Thankfully, in recent years, numbers have rebounded as commercial fishing bans on the breeding ground and nearby areas were put in place. While it’s not yet known how many giant cuttlefish will visit the breeding grounds this season, last year the South Australian Research and Development Institute (SARDI) Cuttlefish Population Survey estimated 247,146—an increase of 116 percent on the previous year, and setting a new record.
Two small cuttlefish “strobing” at each other, while the bull male retreats to find his own action
Although you could say that the recovery in the population has been convincing, as a precaution, a permanent cephalopod fishing closure remains in place at the False Bay/Point Lowly breeding grounds. This closure prohibits the capture of any cephalopods within the area at all times. But just because there is a “no-go” on the breeding grounds themselves, does that mean the species is adequately protected?
Following increased community pressure calling for better cuttlefish protection, this year saw an extension to the existing fishing exclusion zone with the establishment of a new, but temporary 100-meter (330-foot) trial zone. This additional zone remains in place during the 2021 breeding season from May 14 to August 10, 2021. Although the increased protection was welcomed by locals and the tourism community, there is still concern for the cuttlefish. Ocean acidification poses an increased threat to the species, and the migratory paths that the cuttlefish take to reach their important breeding grounds are not themselves protected, thus exposing them to continued recreational and commercial fishing pressure long before they have had a chance to breed.
The heritage-listed Point Lowly Lighthouse stands sentinel, marking the area between the “go” and “no-go” fishing zones. In one area, fishermen gather attempting to harvest cuttlefish on their way to and from the breeding grounds, while in another, dreamy-eyed divers—complete with blue lips and chattering teeth—gather in icy waters to marvel at what is one of the most magical events in the natural world.
A macro lens shows the amazing skin details and coloration
What’s in store for the species remains to be seen. While SARDI has concluded that fishing of the species has a “negligible” impact on populations and the cuttlefish’s future prospects are secure, there is no doubt that the delicate dance between man, nature, and tourism will continue to play out here for years to come. After all, this is the only known dense aggregation of giant cuttlefish, and it happens nowhere else on Earth.
Following Sir David Attenborough’s coverage of the aggregation in the BBC’s Blue Planet series, more and more people have become aware of the event, creating an extraordinary opportunity for the local visitor economy. Recognizing this potential, in 2018, the Whyalla “Cuttlefest,” an annual festival spanning the breeding season from June to August, was founded. Aimed at celebrating the species and educating visitors about the cuttlefish and their importance to our oceans, locals attest that the event has reinvigorated the township, creating an improved sense of community, identity, and most of all, pride. It is evident that this prominent mining and steel manufacturing town is on the cusp of reinventing itself—slowly becoming recognized for hosting one of the greatest shows on the planet.
There is no doubt that witnessing this event is indeed a privilege, and an incredibly rare glimpse of Mother Nature at her absolute finest. With fiery embraces, arguments, and frequent, elaborate costume changes, this is undeniably the tango extravaganza of the seas.
A pair of cuttlefish perform their courting dance
Planning Your Trip to South Australia
Getting There: The annual Australian giant cuttlefish aggregation takes place each year at Point Lowly, near Whyalla—just over four hours’ drive from Adelaide, South Australia’s coastal capital. Adelaide is serviced domestically from all major Australian cities.
When to Go: The giant cuttlefish begin to arrive in the shallow waters of Point Lowly towards the end of May each year, aggregating in the area until around early August. While each season is different, the month of June is considered peak breeding season and believed to offer the highest concentration of giant cuttlefish numbers and the most extraordinary encounters. Keep in mind that the water temperature can get down to a chilly 50°F (10°C), so if you’re not drysuit certified, you’ve been warned!
Who to Dive With: While Covid-19 travel restrictions currently prohibit international travel to Australia, under normal circumstances witnessing this event is easy. The excellent team at Whyalla Diving Services offer guided cuttlefish diving, alongside equipment and tank hire, daily during the breeding season.
Anita and three cuttlefish with the bull male showing off his elaborate colors
About the Authors: Anita Verde and Peter Marshall are published writers, photographers and adventurers. Based in Melbourne, Australia, they have a passion for the planet’s wild places, and through their images, hope to inspire people to better appreciate and protect the natural world. With professional backgrounds in tourism and government relations, when they’re not underwater or on a mountaintop, they work professionally as strategic consultants advising governments and industry on sustainable tourism destination planning and development, brand strategy and marketing. www.summitstoseasphotography.com
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