Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning female Stocky Anthias (Pseudanthias hypselosoma), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Whitemouth Moray (Gymnothorax meleagris) being cleaned by Cleaner Wrasse (Labroides sp) juvenile, Christmas Island, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Yellow-edged Moray (Gymnothorax flavimarginatus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning Honeycomb Moray Eel (Gymnothorax favagineus), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Goldbelly Cardinalfish (Apogon apogonides), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Clown Anemonefish (Amphiprion ocellaris) in sea anemone, Australia

Gary Bell/ Oceanwide / Pink Anemonefish (Amphiprion perideraion) in sea anemone, Great Barrier Reef, Australia

Richard Du Toit / Red-billed Oxpecker (Buphagus erythrorhynchus) on Burchell's Zebra (Equus burchellii), Mkhuze Game Reserve, KwaZulu-Natal, South Africa

Richard Du Toit / Northern Giraffe (Giraffa camelopardalis) with Red-billed Oxpeckers (Buphagus erythrorhynchus) feeding on parasites in symbiotic relationship, Mkhuze Game Reserve, KwaZulu-Natal, South Africa

David Fleetham / Hawaiian pom-pom / boxer crab (Lybia edmondsoni)with anemones (Triactis sp) that it carries around holding with the claws and using them for defense, waving in front of the possible aggressor. An exam...