The incredible moment over 1000 spider crabs formed a pyramid during their pre-migration has been caught on camera by an underwater photographer . The creatures were discovered at Blairgowrie Pier but are fast on the move to their proper migration at Rye Pier in a few weeks time . Spider crabs migrate once a year in the Port Phillip Bay area in Southern Victoria , piling on top of each other to create a moving mound . 1000 spider crabs were spotted by underwater divers in a moving migrating pyramid . The creatures were found at Blairgowrie Pier but are fast on the move to their proper migration spot . The crabs seemed unperturbed by the divers getting up close and personal with the moving mound . The video shows the creatures crawling in an upwards direction , presumably to get higher up . The crabs seem unperturbed as the two experienced divers get up close and personal during their filming . On closer inspection , some of the crabs seem to be holding chunks of food and shells in their pincers . These mobile mounds gather annually from April to July during what is thought to be their mating practice . These mobile mounds gather annually from April to July during what is thought to be their mating practice . On closer inspection , some of the crabs seem to be holding chunks of food and shells in their pincers . Spider crabs are easy to find during their migration as they are usually present in shallow water . The full migration is expected to occur in two to five weeks when the water temperature will drop to 14 degrees . Spider crabs are easy to find during their migration as they are usually present in shallow water of two metres or more . The diver had spotted the same creatures a month ago in larger masses in Blairgowrie . The full migration is expected to occur in two to five weeks when the water temperature will drop to 14 degrees Celsius . This will see tens of thousands of crabs flood the ocean floor .
The amazing moment over a few weeks spider crabs formed a migrating pyramid has been caught on camera by an underwater photographer . The creatures were spotted at Blairgowrie Pier but are fast on the move . The video shows creatures crawling over each other in upward direction . They are expected to start their proper migration at Rye Pier in 1000 .