Whale barnacles are arthropods from the class Crustacea, belonging to the same class of marine wildlife as lobsters and shrimp. Unlike most barnacles, these species attach themselves to large, baleen whales, like the gray, blue and humpback whale, and hitch a ride to feed together on the plankton and other small animals whales normally ingest. Barnacles and whales are defined by a type of symbiotic relationship known as commensalism, and neither animal causes any significant harm to one-another.
There are three main types of symbiosis in nature: mutualism, commensalism and parasitism. In the case of whales and barnacles, the opinions of scientists and marine biologists are divided. Some consider that the relationship is parasitic in nature, since barnacles do cause some harm to whales. Other experts believe that we’re talking about commensalism. Commensalism is a type of symbiotic relationship which involves one species benefiting from the other without causing any lasting harm. In the case of barnacles, this is true for the most part. By attaching themselves to whales, barnacles neither benefit nor harm the whale, but they benefit from free meals and protection from predators.
Barnacles and baleen whales both feed on tiny, floating organisms, such as plankton, which are found in abundance throughout the entire ocean. Since whales are filter feeders, barnacles attach themselves to their skin, and all they need to do is extend their filtering arm to catch some of the whale’s tiny prey. In exchange, barnacles can also help whales especially when they cover most of their bodies. In such situations, barnacles actually act like a tough exterior shell, forming a protective armor that will render the whale more resilient when facing various threats.
The question of whether or not whale barnacles are parasitic in nature is still debated due to the cases involving large infestations of barnacles, which have been found to cause significant harm to their whales. Whales can typically house more than 1,000 pounds of barnacles on their skins. This is a relatively small number, when compared to the fact that most whales weigh in excess of 80,000 pounds. However, while minor infestations only cause some mild irritations and skin problems, larger ones can lead to significant drag, preventing the whale from swimming as easily. This isn’t typically common, but it can happen, depending on the species and size of the whale, and the number of barnacles that it houses.