Naomi Strong, Giant Spider Crab Migration (Wildlife and Animal 2019)

Every year in winter thousands and thousands of Giant Spider Crabs aggregate in the shallows of Port Phillip Bay, Melbourne, Australia. They come into the shallows to moult their old shells, gathering together for protection against predators such as octopus, cormorants and the huge smooth rays that patrol the bay like clockwork from the moment this natural phenomenon occurs. A freshly moulted spider crab is at its most vulnerable while it waits for its new shell to harden. During the few hours of waiting, the crabs are very weak and can barely stand or walk let alone defend themselves which means many become a tasty meal for their natural predators. Those that survive try to hide, crawling under anything they can find or climbing to high vantage points. Once their shells have completely hardened they turn a bright orange colour and slowly make their way back to deeper waters for another year leaving the sea floor littered with their discarded bodies.

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