Certain whales have an intriguing relationship with small marine animals

There are several intriguing reasons behind why so many barnacles end up hitching a ride with whales — an unlikely alliance between marine mammals and small shelled marine animals.

According to, Geoffrey Boxshallprofessor and specialist in small crustaceans at the Natural History Museum in London and member of the Royal Society, explained what the reasons for this event.

Firstly, it may have to do with the whale behavior. Boxshall explained that they “move through the well-lit, productive surface waters of the oceans, where small plankton — food for barnacles — is abundant.”

Secondly, “the large size of whales provides plenty of surface for barnacles to attach to.”

And then there is the factor of social habits of many whale specieswhich may play an important role in giving barnacles more opportunities to spread.

“As whales come together to mate and feedand often travel in large groups, which provides many opportunities for barnacle larvae to find and attach to whales. Otherwise, the ocean is huge for barnacle larvae, which are only 1 to 2 millimeters long, and need to find their ‘host’ before they run out of larval food,” Boxshall said.

As barnacles are taxonomically crustaceanswhich means they are related to crabs, lobsters, shrimp and prawns. However, they do not look like most other members of this family.

With more than 2,000 distinct speciesits defining feature is the hard calcareous shell, usually shaped like a striated dome. Inside the shell, they look like small creatures with feathery legs, wearing jointed appendages called cirrhosis, to sweep plankton and debris from the water into the mouth.

Unlike most crustaceans, barnacles are sessilepermanently attaching itself to rigid structures such as rocks, ship hulls or whales.

Barnacles also colonize other marine animals, especially barnacles.sea ​​turtle shellswhich offer an excellent surface to install on.

They already were observed in sharks and dolphinsalthough less frequently.

Barnacles don’t harm whales. Fortunately, they are largely harmless and simply hitchhike.

“The way they feed is essentially the same as a typical barnacle attached to a rock on the coast. The difference is that they attach themselves to a ‘moving rock’, which transports them and gives them constant access to new sources of plankton,” explained Boxshall.

“They are not parasitesbecause they do not cause significant harm to the whale”, he adds.

However, the same cannot be said about other marine animals. Boxshall commented: “Sharks sometimes have barnacles, but these are parasites and remove nutrients from the host“.

As gray whales are probably the most susceptiblewith some individuals carrying more than 180 kg of barnacles and whale lice.

As blue whales and orcas (which are technically dolphins) they have almost no barnaclesprobably due to their smooth, gummy skin. Orcas are also known to groom each other in the kelp forest, which can help remove organisms stuck to their skin.

“Barnacle loads vary among host species — almost certainly due to differences in behavior: food preferences, geographic distribution, depth, migrations, etc.”, concluded Boxshall.

It is likely that the relationship between whales and barnacles began millions and millions of years ago. It’s impossible to know for sure without direct evidence, but it’s easy to imagine that this convenient partnership came into being not long after the first whales returned to the ocean, about 50 million years ago.