“The first time you go and put your head underwater and see hundreds and hundreds of sepia in this small area, it looks like a chaotic kaleidoscope,” says Tony Bramley.
As the owner of Whyalla Diving Services and a decades-long advocate of the Australian cuttlefish, Bramley has watched for years the frenetic, colorful cuttlefish mating that takes place in the Spencer Gulf Northern Marine Park in South Australia.
Once only of interest to local fishermen and divers – who tried to warn each other that “the cuttlefish were in the area” – this marine phenomenon now attracts tourists and researchers from all over the world.
It’s a welcome boost to the small steel town of Whyalla on South Australia’s Eyre Peninsula.
Cuttlefish – a type of marine invertebrate that is closely related to the octopus – are intelligent molluscs capable of instantly changing color and texture.
They have been known to be able to escape labyrinths and can hypnotize their prey by turning their bodies into strobe lights, quickly emitting colors through their skin to distract and stun an unsuspecting crab or fish.
Its camouflage abilities put chameleons to shame and have even caught the attention of US military personnel, who have researched the color-changing abilities of sepias in hopes of replicating their techniques for military use.
If that’s not unusual enough, their mating behaviors are strange, to say the least.
From May to September each year, hundreds of thousands of Australian cuttlefish gather in the waters off Point Lowly, in the northernmost part of Spencer Gulf, for the sole purpose of mating.
That’s when nature’s wildest underwater sex show takes place.
The world’s largest cuttlefish are found in the waters off southern Australia, but only in Whyalla do they come together in large numbers to mate.
“The estimated number of cuttlefish in the 2020 reproductive aggregation was 247,000, the highest ever recorded,” said Bronwyn M Gillanders, a renowned cuttlefish researcher and head of the school of biological sciences at the University of Adelaide in Australia.
“This number has been reported, but we know it’s probably an underestimate.”
According to Gillanders, Whyalla attracts cuttlefish because of its unique seascape.
The northernmost region of the Spencer Gulf offers many rocky outcrops that females use to lay their eggs.
Although cuttlefish mate elsewhere, Spencer Gulf is home to the largest known aggregation on the planet.
There is no other place in the world where you can observe such spectacular and strange mating behavior en masse, including color changes and males masquerading as females.
Nobody said finding a partner was easy – and these cuttlefish are single and ready to mingle – but first, they need to get to the party.
Bramley explains that some cuttlefish were marked, revealing that some of them travel at least 65 km south of the city and another 35 km north to reach the breeding grounds in Spencer Gulf.
Arriving in Whyalla, it is easy to observe the cuttlefish, whether diving with an oxygen bottle or just snorkeling – the cephalopods are found close to the coast, between 2 and 6 meters.
Although the water is calm, it is not hot.
“You really need to dress for the occasion,” says Bramley with a laugh.
With the ocean temperature around 10-16°C, I came prepared with a thick wetsuit, hood, gloves and boots.
Even so, the cold hit me hard – but once I was underwater, I had a front-row ticket to the most amazing show in town.
Once my eyes adjusted, I realized I was surrounded by cuttlefish – and they didn’t seem the least bit bothered to have a human watching their most intimate moments.
With a vibrant, pulsating rainbow of purple, orange, turquoise and pink – and tentacles everywhere – it took me some time to understand the cephalopod flirtation, as sepias have more than a few seduction gimmicks in their tentacles.
In an environment where males can outnumber females by a ratio of 10 to 1, the competition to pass on genes is fierce.
In most species, size matters: large, aggressive males fight their rivals for the chance to mate.
This is also observed in the case of cuttlefish – large males have been known to fight each other for dominance in the presence of a female.
For any other species, this means smaller males are left out. But sepias are not like any other animal. They discovered that if you want to impress a crushyou need to use creativity.
“The smaller males have a dilemma on their hands, because they know they can’t beat these much larger males,” explains Sarah McAnulty, a squid biologist at the University of Connecticut, USA.
“They came up with an alternative approach – disguising themselves as a female to avoid battle.”
It is perhaps the most fascinating mating behavior of any species – smaller males can fade their translucent coloration, reaching the burgundy and mottled white of a female, before tucking their wavy arms around their bodies.
This makes them look like females, and as the burly males are busy fighting each other, leaving their potential mate vulnerable, the little ones dart past them in disguise to gain access to the female – and then quickly change back to coloring. of male: point for the shrewd underdog.
If the female decides to mate, the ensuing spectacle might make you wonder if the sepia was inspired by non-18-year-old movies.
Amidst the tangle of tentacles, the cuttlefish connect, and the male deposits his sperm packet into the female’s mouth, using a specially developed arm, known as a hectocotyl.
The female then retains the sperm until she is ready to lay her eggs.
The female mates with several males and may use a mixture of different sperm deposits for her eggs.
Interestingly, females prefer smaller males than their muscular counterparts, according to McAnulty, indicating they are selecting for brains rather than muscle.
“Studies have even shown that when females go to lay their eggs, they give a higher proportion of paternity to these cunning males,” she says.
“So when we wonder how these goddamn cephalopods got so smart? It’s because they’re sexually selecting for it!”
While there is no shortage of censored action for under-18s underwater today, it wasn’t always that way.
Over the past few decades, overfishing in the region has reduced the local cuttlefish population, which has encouraged residents to take action.
This led to the creation of a fishing exclusion zone in 2013 along the northern part of Spencer Gulf during the breeding season.
In the late 1990s, aggregation numbers were at their lowest – Bramley estimates there were only 30,000 to 40,000 sepias present in 1999.
In a twist of fate, the decline in the sepia population has attracted media attention.
Once word got out about Whyalla’s amazing cephalopods, the region slowly began to attract divers and tourists in the early 2000s, eager to observe what was then a relatively unknown marine phenomenon.
In recent years, sepia’s peak season has resulted in overcrowded hotels and restaurants, and the injection of funds from tourism has been a welcome boost to an economy that relies primarily on steel production.
Although there is talk of building more hotels to meet the influx of tourists, the sepia season only lasts three to four months, how do tour operators sustain themselves then for the rest of the year?
One solution the city hopes will help is to improve infrastructure, with a $4 million grant for the Sepia Shrine Conservation and Tourism Project, announced in 2021.
This will help the city manage additional visitors each season and promote Whyalla as a nature tourism destination with easier access to beaches and trails, better signage, the addition of more native vegetation and greater protection of the region’s delicate ecosystems.
Although Whyalla’s sepia tourism is only in its second decade, the town hopes it will become a viable long-term source of income.
As for the sepias themselves, we can only hope they keep up their blatant sexual antics, proving that life can be as colorful and wild as you want it to be.