Agustin Esmoris / Southern Right Whale (Eubalaena australis) surfacing with Kelp Gull (Larus dominicanus) picking off lice, Chubut, Argentina, sequence 1 of 4

Tony Wu / Humpback whale (Megaptera novaeangliae) adult female at rest. The tubercles on the whale's head are clearly visible, as are the barnacles (Coronula diadema), whale lice (Cyamus boopis), and hairs on t...

Agustin Esmoris / Southern Right Whale (Eubalaena australis) surfacing, showing callosites covered with barnacles and lice, Chubut, Argentina

Agustin Esmoris / Southern Right Whale (Eubalaena australis) surfacing with Kelp Gull (Larus dominicanus) picking off lice, Chubut, Argentina, sequence 3 of 4

Tony Wu / Whale louse (Cyamus ovalis) on a Southern right whale (Eubalaena australis) South Africa. Photographed with the permission of the Department of Environmental Affairs, South Africa.

Tony Wu / Whale louse (Cyamus ovalis) on hand to show scale, came from a Southern right whale (Eubalaena australis) South Africa. Photographed with the permission of the Department of Environmental Affairs, Sou...

Tony Wu / Southern right whale (Eubalaena australis) inquisitive adult approaching to observe diver, note the callosity above the whales eye, which is populated by other organisms, including whale lice (Cyamus...

Tony Wu / Southern right whale (Eubalaena australis) at surface showing callosity on head with huge number of Whale lice (Cyamus ovalis) amongst other organisms, photographed with the permission of the Departme...

Tony Wu / Southern right whale (Eubalaena australis) calf resting its head on top of its mother, already with Whale lice (Cyamus ovalis) on its skin, photographed with the permission of the Department of Enviro...

Tony Wu / Southern right whale (Eubalaena australis) looking down on calf's head showing the development of callosities with whale lice (Cyamis ovalis) photographed with the permission of the Department of Envi...

Tony Wu / Researcher reaching over to take samples of Whale lice (Cyamus ovalis) from one of the callosities on Southern right whale (Eubalaena australis) at surface, photographed with the permission of the Dep...

Tony Wu / Humpback whale (Megaptera novaeangliae) close up of female with open nostrils surfacing to breathe, note the whale lice (Cyamus boopis) Vava'u, Tonga, South Pacific