Creature Feature: Pandarus rhincodonicus

Andrew Hosie's blog | Created 1 decade ago

Even the biggest animals have fleas, and the mighty whale shark is no exception. Pandarus rhincodonicus, is a small crustacean, barely reaching one centimetre in length, belonging to a group of crustaceans known as copepods which are normally known to be free-living and a dominant group within planktonic communities. However, many species are bottom dwellers or parasites of other marine animals, particularly fish. Pandarus rhincodonicus was first discovered in WA and was only named and formally described in 2000.

So what does Pandarus rhincodonicus do? Well, it is normally found facing forwards on the leading edges of a whale shark’s fins or lips. Pandarus rhincodonicus is not likely to be feeding on or causing any harm to the host shark. Keep in mind that a whale shark’s skin is 11 cm thick and the mouthparts of this small crustacean are not going to penetrate it. The serrated mandibles are instead better adapted for scraping microscopic bacteria and algae from the surface of the shark’s skin. In this sense this little copepod is likely to be of some benefit to the host through keeping the skin clean.

Holding on to a swimming whale shark isn’t easy and requires special adaptations. This crustacean has a number of hooks on its antennae, adhesion pads and strong grasping limbs to grip the whale shark’s skin and prevent it from being whipped off the whale shark as it swims. Its body is also dome shaped and acts as a living suction cup to help hold the small animal in place.

Two specimens of Pandarus rhincodonicus collected from a whale shark at Ningaloo Reef.

Photo by Andrew Hosie.

Image copyright of WA Museum