Every year, in the waters of Port Phillip Bay off Melbourne, Australia, thousands of Giant Spider Crabs gather as they shed their old skin to allow for growth and form a new shell, according to Museums Victoria.
“The process of moulting takes up to an hour and all the crabs in an aggregation moult almost simultaneously,” Museums Victoria says. The organization said that by grouping together the crabs reduce their chance of being eaten by predators while they are exposed.
Freediver Julie Casey, who lives in the area, shot this footage of a congregation on June 4. Casey records many of her marine adventures and posts them to her Instagram account. Credit: @onebreathdiver via Storyful