There is an amazing natural spectacle taking place each year in Australia, in Port Phillip Bay and other places along the Great Southern Reef - the gathering of massive numbers of spider crabs.

 

Spider crabs need to shed their hard shell in order to grow bigger (a process called moulting). After this, they are soft and very vulnerable to predators. This is why we think they gather in such high numbers - to seek safety in numbers! However, they also gather at other times of year for unknown reasons. These spider crabs only live in Australia. Aggregations are known to occur in parts of the Victorian coast, in Tasmania, and we've found out more recently that there used to be (and perhaps still are) aggregations in South Australia.

 

With your help, our research team would like to gather information on one of the most mysterious natural wonders!