Certain species of barnacle can best be described as the ‘hitchhikers of the ocean’. They have a commensal relationship with whales, which means they benefit from hitching a ride on one, without seeming to affect the whale in any way. They are both filter feeders, so the barnacles are taken straight to their food source by the whale, and then all it has to do is then extend its feathery filtering arm to feed.
There are many different species of whale bound barnacles. The one that latches onto the humpback whale is called Coronula diadema. One whale can carry a barnacle load of more than 450kg, but considering their immense weight, this is not really too burdensome.