Doug Perrine / RF- Green sea turtle (Chelonia mydas) being cleaned by herbivorous cleaner fish species Yellow tangs (Zebrasoma flavescens) and Gold-ring surgeonfish (Ctenochaetus strigosus) that graze algae on turtl...

Staffan Widstrand / RF- Greater Kudu (Tragelaphus strepsiceros) male portrait with oxpecker birds on back, St Lucia wetlands National Park, South Africa. (This image may be licensed either as rights managed or royalty fr...

Doug Perrine / RF- Oceanic whitetip shark (Carcharhinus longimanus) with pilot fish (Naucrates ductor). Kona Coast, Hawaii, Central Pacific Ocean. (This image may be licensed either as rights managed or royalty free...

Doug Perrine / RF- False clown fish (Amphiprion ocellaris) among tentacles of host sea anemone (Heteractis magnifica), Surin, Thailand. (This image may be licensed either as rights managed or royalty free.)