Whale Barnacle

The whale barnacle is a species of barnacle that lives exclusively attached to the skin of humpback whales and certain other large baleen whales, unable to survive independently of its host. Rather than sitting on the surface of the skin like most barnacles on a hard substrate, it embeds part of its base into the whale's own tissue, anchoring itself firmly against the drag of open water swimming. Its shell forms a distinctive crown or rosette shape, often clustered in patches on the whale's head, flippers, and tail. It reproduces and feeds by filtering plankton from the water as the whale swims, relying entirely on its host's movement through productive feeding grounds to bring food within reach. Because it settles onto whale calves early in life and remains for the whale's lifetime, the size and pattern of its colonies are sometimes used by researchers to help identify or age individual whales. It has no known ability to attach to any surface other than living whale skin.