A diver from Victoria’s Mornington Peninsula shared her excitement on Instagram recently when she encountered hordes of giant spider crabs as the crustaceans gathered for molting season.Marine biologist Sheree Marris said it was the first time this year that she encountered the species, which will gather in their thousands over the next few months.“The reason? Safety in numbers,” she wrote. “To grow they need to molt their hard exoskeleton and grow a new one.” Gathering during this vulnerable time increases the chances of survival.“Looking forward to seeing more of these long-legged crustaceans as they start building in numbers… not looking forward to the water getting colder though,” Marris said.Marris regularly documents the local marine life for her Instagram account. Credit: Sheree Marris via Storyful