Meet the giant clam, a member of Queensland’s Great Eight
Africa might be home to The Big Five but Queensland boasts its own collection of mesmerising marine life, The Great Eight. The giant clam has definitely earnt its way onto this thrilling list alongside the likes of clownfish, manta rays, maori wrasse, potato cod turtles, sharks and whales.
Introducing the giant clam
These extraordinary molluscs, which can grow to 1.5 metres in length and weigh up to 200 kilograms, feature a pretty ordinary exterior but a stunning mantle – the fleshy part protruding from the shell. It’s said that, like a human fingerprint, no two clams have the same mantle pattern or colours. These wild technicolour effects actually come from algae living within the clam’s tissue. In the wild, the world’s largest bivalve mollusc lives for around a century.
All clams commence life as males, eventually switching to hermaphrodite status. At spawning time, chemical signals trigger clams to release either sperm or eggs, the largest releasing up to 500 million eggs at one time. Once fertilised, the eggs enter a swimming stage and then a planktonic stage before they settle down into the reef for the rest of their lives.
Where to spot them
Magnetic Island, Townsville
There are two self-guided snorkel trails on “Maggie”, a popular day-trip for locals and tourists being just 25 minutes by ferry from Townsville. Perfect for snorkellers who want to understand what they’re seeing, the trails are marked out by white surface and subsurface floats. Nelly Bay is the easiest for beginners, starting 100 metres off the beach. Information cards guide the snorkeller through gardens of lettuce, cauliflower, boulder and staghorn corals teeming with colourful clownfish and giant clams. The Geoffrey Bay snorkel trail offers the added thrill of viewing the remains of a shipwreck, the SS Moltke, and part of a World War II fighter plane.
Orpheus Island, Townsville
The first thing you might notice here is a huge field of giant clams outside the Orpheus Island Research Station, squirting seawater during low tide, the result of an abandoned clam-farming experiment. To clean and expel sand and grit washing over their muscles, the clams squirt seawater high into the air. Orpheus has some of the most colourful coral outcrops (known as bommies) on the entire Great Barrier Reef, along with more than 1,000 species of reef fish, 340 varieties of hard corals and one of the region’s largest collections of soft corals. It’s just over an hour from the island to reach the outer reef, home to green turtles, manta rays, bull rays and reef sharks.
Hayman Island, Whitsundays
The closest of the Whitsunday Islands to the outer reef, Hayman hotspots include Blue Pearl Bay, where you can swim among soft and hard corals and a multitude of marine life. You may also meet Priscilla, the resident giant Maori wrasse. Nearby Langford Reef has a long sandy spit with a small but richly populated reef encircling the island, as well as fields of seagrass frequented by turtles. Nearby tiny Black Island, also known as Bali Hai, is largely undisturbed by big tour operators. In its shallow aqua waters you can spot green sea turtles, giant clams, colourful corals and reef fish.
Green Island, Cairns
Highly popular with day-trippers – it’s just a 45- minute boat ride from Cairns – Green Island’s coral gardens and rich marine life begin almost the moment you step off the sandy beach. Both hard and soft corals proliferate, supporting giant clams, anemones and sea cucumbers, while the rich diversity of fish life includes coral trout, butterflyfish, angelfish, fusiliers, chromis, clownfish and parrotfish as well as turtles and reef sharks. The best snorkelling is around the jetty, particularly in the mornings when the water is calm and visibility is at its best. With its own lifeguard service, Green Island is not only one of the most accessible reef islands to snorkel, but one of the safest. The coral gardens of the nearby Flynn Reef are also known as a giant clam haven.
Hastings Reef, Cairns
Hastings Reef is renowned for spectacular coral formations, with residents including parrotfish, turtles, giant clams, small reef sharks and brilliant yellow butterflyfish. Visit the reefs in late October and November (dates vary) to witness the coral spawning.
Ribbon Reefs, Tropical North Queensland
Also beloved by divers, who come for the spectacular drop over the Coral Sea trench along with the kaleidoscope of colourful sea life, the Ribbon Reefs are a long necklace of individual reefs running parallel to the continental shelf. Sitting about 65 kilometres off the coast of Port Douglas, the reefs are notable for their water visibility and pristine ecosystem. Shallow lagoons are rich in coral growth, with spectacular giant clams residing at a dive site called the Clam Gardens.