Every year, thousands of giant spider crabs (Leptomithrax gaimardii) aggregate in Port Phillip Bay, an enormous inlet on the south coast of Victoria in Australia. It's the largest known gathering of these crabs in the world.
The reason for the mass gathering is still a bit of a mystery. The leading theory is that the crabs come together as a form of protection while moulting their hard shells (which allows them to grow). While shedding, and during the few hours after, the crabs' soft bodies make them vulnerable to predators – the more there are of them in one place, the better chance they have of survival.
The sight of these large crabs marauding across the seafloor and clambering all over each other is breathtaking, as this footage recorded in 2021 shows.
- “A colossal crab the size of a car tyre was pushing against my door”
- “It’s not over yet.” Filmmakers deployed a robot crab into the sea. How the other crabs reacted was extraordinary
Image and video credit: Joel Sharpe/Getty Images
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