These egg to fist sized crustaceans are found on humpback whales (and reported from fin, blue, and sperm whales) especially on the lips, the long grooves of the throat and the genital region.
Barnacles begin their lives as free-swimming larvae, but appear able to ‘smell’ a nearby whale when ready to settle down. They then develop the heavy calcium-rich plates that shield the barnacle’s soft body (now lost in this specimen). As the plates fuse together, the whale’s skin is drawn into the spaces between the plates, permanently stitching the barnacle’s shell to the whale. Even though the barnacle may only live for one to two years, the whale carries the shell around until it can find a way to scrape it off.
Luckily, the barnacles only attach to the surface layer of the whale’s very thick skin and blubber layer. They don’t harm the whale, just hitchhike through the plankton-rich water that the whales enjoy.