Large infestations may weaken the dog and make it susceptible to other illnesses. In Africa there exists an unusual relationship between ants and the Acacia tree. The tree provides food for the ants, and the ants protect the tree from predators. There is a white bird that feeds on the particles of food left between the Hippopotamus' teeth. The Hippo does not harm the bird and benefits from the teeth cleaning.
Mosquitoes carry the larva of the heartworm.
Their bit may infect a dog. The heartworm larvae infect the dog's heart, where they may live for some time before killing the dog. Barnacles have no means of locomotion and may reside on the skin of a whale. The whale is unaware that the barnacles are there, but the barnacles get a free ride from place to place. Ringworm is really a type of fungus that causes a ring-shaped itchy place on the skin of humans.