Whale barnacle

Whale barnacles are barnacles belonging to the family Coronulidae. Whale barnacles attach themselves to the bodies of baleen whales during the barnacles' free-swimming larval stage. Some sources describe the relationship as an example of obligate commensalism, as when the barnacles neither harm, nor benefit, their host. Others describe the relationship as parasitic. The relationship is parasitic when whales are harmed by the barnacles. Such harm occurs when heavy infestations cause drag and reduce swimming efficiency. In addition, barnacle infestations can aid other parasites especially cyamids. Whale barnacles that, through circumstance, are forcibly detached from their whale have been noted to experience apoptotic necrosis triggering the decline and eventual demise of the individual. A number of taxa formerly treated as subfamilies of Corolunidae are now considered separate families in their own right, including the turtle barnacles in the family Chelonibiidae.