Xenobalanus globicipitis

One of the main problems with photo-ID of dolphins using their dorsal fins is that often the dorsal fin is covered with a soft-bodied barnacle known as Xenobalanus globicipitis, "Xeno".

Xeno firmly attaches to it's host with a star shaped foot plate. These barnacles can usually be seen hanging from trailing edges of pectoral fins, dorsal fins, and the tail flukes of bottlenose dolphins. Xeno does not draw nutrients from its host, but feeds in barnacle fashion by straining out plankton from the surrounding water with feather like appendages (cirri).

We have observed high numbers of Xeno present on bottlenose dolphins during the months of September and October. Sometime these barnacle are so numerous that the entire trailing edge of a dolphin's dorsal fin is completely covered. This obscures any notches, nicks or other identifying marks, rendering a photograph useless for photo-ID. To make matter worse the next time we see this dolphin he may not have any Xeno at all.

Below are some pictures of Xeno on the dorsal fin: