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

Alex Mustard / Reef lizardifsh (Synodus variegatus) at a cleaning station, being cleaned by Holthuis anemone shrimps (Ancylomenes holthuisi). Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Michael Pitts / Giant manta ray (Manta birostris) swimming over a cleaning station, Maldives, Indian Ocean.

Claudio Contreras / Giant Manta Ray (Manta birostris) at cleaning station with Clarion Angelfish (Holacanthus clarionensis) San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve (The Socorro Islands), Pacific...

D. Parer & E. Parer-Cook / Galapagos Land Iguana (Conolophus subcristatus) with a Small Ground-Finch (Geospiza fuliginosa) on its head removing parasites, Galapagos Islands, Ecuador

Chris Newbert / Scarlet Cleaner Shrimp (Lysmata amboinensis) pair cleaning a Moray Eel (Gymnothorax ocellatus) 80 feet deep, Solomon Islands

Norbert Wu / Green Sea Turtle (Chelonia mydas) being cleaned by Yellow-eyed Surgeonfish (Ctenochaetus strigosus), Hawaii

Norbert Wu / Green Sea Turtle (Chelonia mydas) being cleaned by reef fish, Hawaii

Fred Bavendam / Scarlet Cleaner Shrimp (Lysmata amboinensis) working on a Tomato Grouper (Cephalopholis sonnerati), Milne Bay, Papua New Guinea

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) cleans among the sharp teeth of a predatory roving coral grouper (Plectropomus pessuliferus) beneath an overhang on a coral reef. Ras Mohammed National...

Alex Mustard / Reef manta (Mobula alfredi) visiting a cleaning station on a coral reef with a school of Onespot snappers (Lutjanus monostigma), Oriental sweetlips (Plectorhinchus vittatus) and Sabre squirrelfish (Sa...

Melvin Grey / Cape buffalo (Syncerus caffer caffer) portrait, Red-billed oxpeckers (Buphagus erythrorhynchus) removing parasites. Nakuru, Kenya.

Tony Wu / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Luna lionfish (Pterois lunulata). Shizuoka Prefecture, Honshu, Japan. June.

Shane Gross / Black grouper (Mycteroperca bonaci) with Remora fish (Remora sp). Caribbean Sea off Gardens of the Queen National Park, Cuba.

Gary Bell/ Oceanwide / Blue-streaked Cleaner Wrasse (Labroides dimidiatus) cleaning mouth and gills of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

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 / Meyer's Butterflyfish (Chaetodon meyeri) being cleaned by Blue-streaked Cleaner Wrasse (Labroides dimidiatus), Great Barrier Reef, Queensland, Australia

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

Gary Bell/ Oceanwide / Emperor Angelfish (Pomacanthus imperator) juvenile being cleaned by Scarlet Cleaner Shrimp (Lysmata amboinensis), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Emperor Angelfish (Pomacanthus imperator) juvenile being cleaned by Scarlet Cleaner Shrimp (Lysmata amboinensis), Tulamben, Bali, Indonesia

Gary Bell/ Oceanwide / Blue-streaked Cleaner Wrasse (Labroides dimidiatus) cleaning gills of Semicircle Angelfish (Pomacanthus semicirculatus), Great Barrier Reef, Australia

David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus) feeding on parasites on Crocodile needlefish (Tylosurus crocodilus) with coral reef below. Hawaii.

David Fleetham / Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning Redlip parrotfish (Scarus rubroviolaceus) in coral reef. Kauai, Hawaii.

David Fleetham / Great barracuda (Sphyraena barracuda) with two endemic Hawaiian cleaner wrasse (Labroides phthirophagus) cleaning it. Hawaii.

Alex Mustard / Emperor angelfish (Pomacanthus imperator) with Cleaner shrimp (Urocaridella sp.) grooming it. South Ari Atoll, Maldives. Indian Ocean.

Alex Mustard / Reef manta (Mobula alfredi) at a cleaning station with Cleaner wrasse (Labroides dimidiatus). South Ari Atoll, Maldives. Indian Ocean.

Alex Mustard / Blue tang (Acanthurus coeruleus) with Bluehead (Thalassoma bifasciatum) juveniles at cleaning station on coral reef. George Town, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea. Digi...

Alex Mustard / Florida manatee (Trichechus manatus latirostrus) with Blue gill sunfish (Lepomis macrochirus) cleaning it, in a freshwater spring, beneath trees. Three Sisters Spring, Crystal River, Florida, USA

Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) sticking its head into the mouth of a Red Sea fusilier (Caesio lunaris) during a cleaning session. Small Crack, Sha'ab Mahmud, Sinai, Egypt. Red Se...

Nature Production / Commensal crinoid shrimp (Periclimenes amboinensis) cleaning Wrought-Iron butterflyfish (Chaetodon daedalma) Chichijima, Ogasawara Islands UNESCO World Heritage Site, Japan

Georgette Douwma / Thresher shark (Alopias pelagicus) swimming over seabed to be cleaned by cleaner wrasses, Cebu, Malaspascua, Philippines, September

Georgette Douwma / Thresher shark (Alopias pelagicus) swimming over seabed to be cleaned by cleaner wrasses, Cebu, Malaspascua, Philippines, September

Georgette Douwma / Thresher shark (Alopias pelagicus) swimming over seabed to be cleaned by cleaner wrasses, Cebu, Malaspascua, Philippines, September

Tony Wu / White-spotted pufferfish (Arothron hispidus) being cleaned by Bicolor cleaner wrasse (Labroides bicolor) Ambitle Island, one of the two islands in the Feni Island group, New Ireland, Papua New Guinea.

Tony Wu / Potato cod (Epinephelus tukula) being cleaned by Bluestreak cleaner wrasse (Labroides dimidiatus) Carl's Ultimate dive site in the Eastern Fields of Papua New Guinea

Tony Wu / Potato cod (Epinephelus tukula) being cleaned by Bluestreak cleaner wrasse (Labroides dimidiatus) Carl's Ultimate dive site in the Eastern Fields of Papua New Guinea

Tony Wu / Giant moray eel (Gymnothorax javanicus) being cleaned by Scarlet cleaner shrimp (Lysmata amboinensis) Ambon, Indonesia

Tony Wu / Giant moray eel (Gymnothorax javanicus) being cleaned by Scarlet cleaner shrimp (Lysmata amboinensis) Ambon, Indonesia

Pascal Kobeh / Pyramid butterflyfish (Hemitaurichthys polylepis) being cleaned by a common cleanerfish (Labroides dimidiatus) Palau, Philippine Sea

Pascal Kobeh / Spanish hogfish (Bodianus rufus) is cleaning a Blue tang surgeonfish (Acanthurus coeruleus) Yucatan Peninsula, Mexico

Georgette Douwma / Doublelined fusilier (Pterocaesio digramma) with two Cleaner wrasses (Lutjanus dimidiata) inside its gill, West Papua, Indonesia.

Alex Mustard / Cleaner wrasse (Labroides dimidiatus) swims out from the gill of a Blue spotted pufferfish (Arothron caeruleopunctatus). East of Eden, Similan Islands, Thailand. Andaman Sea, Indian Ocean.

Jordi Chias / Reef manta ray (Manta alfredi) being cleaned by small wrasses at cleaning station, South Ari atoll, Maldives, Indian Ocean

Jordi Chias / Reef manta ray (Manta alfredi) being cleaned by small wrasses at cleaning station, South Ari atoll, Maldives, Indian Ocean

Juergen Freund / Giant manta rays (Manta birostris) at a cleaning station with cleaner wrasses. North Raja Ampat, West Papua, Indonesia

Juergen Freund / Giant manta rays (Manta birostris) at a cleaning station with cleaner wrasses. North Raja Ampat, West Papua, Indonesia

Pascal Kobeh / Two Bluestreak cleaner wrasses (Labroides dimidiatus) one a juvenile, cleaning a Giant moray (Gymnothorax javanicus) Maldives. Indian Ocean.

Pascal Kobeh / Bluestreak cleaner wrasses (Labroides dimidiatus) cleaning a Giant moray (Gymnothorax javanicus) Maldives. Indian Ocean.

Pascal Kobeh / Two Bluestreak cleaner wrasses (Labroides dimidiatus) one a juvenile, cleaning a Giant moray (Gymnothorax javanicus) Maldives. Indian Ocean.

Pascal Kobeh / Blacksaddle grouper (Plectropomus laevis) cleaned by a common cleaner fish (Labroides dimidiatus) Maldives. Indian Ocean.

Pascal Kobeh / Humphead parrotfish (Bolbometopon muricatum) above coral reef, cleaned by two Blue streaked cleaner wrasses (Labroides dimidiatus) among Jewel fairy basslets / anthias (Pseudanthias squamipinnis) Suda...

Pascal Kobeh / Blackfin barracudas (Sphyraena qenie) in open water cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) Sudan. Red Sea.

Pascal Kobeh / Brown-marbled grouper (Epinephelus fuscoguttatus) laying on sandy sea floor, whilst cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) Sudan. Red Sea.

Pascal Kobeh / Bluestreak cleaner wrasses (Labroides dimidiatus) cleaning Bigeye emperor (Monotaxis grandoculis) Sudan. Red Sea.

Pascal Kobeh / Lemonfish / Gold-spotted sweetlips (Plectorhinchus flavomaculatus) cleaned by two Bluestreak cleaner wrasse (Labroides dimidiatus), coast of Dhofar and Hallaniyat islands, Oman. Arabian Sea.

Pascal Kobeh / Two Bluestreak cleaner wrasses (Labroides dimidiatus) cleaning, Oblique / diagonal banded sweetlips (Plectorhinchus lineatus) New Caledonia. Pacific Ocean.

Pascal Kobeh / Two Bluestreak cleaner wrasses (Labroides dimidiatus) cleaning, Oblique / diagonal banded sweetlips (Plectorhinchus lineatus) New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) just swimming out of mouth of Oblique / Diagonal banded sweetlips (Plectorhinchus lineatus) whilst cleaning / feeding, New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) just swimming out of mouth of Oblique / Diagonal banded sweetlips (Plectorhinchus lineatus) whilst cleaning / feeding, New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Diagonal banded sweetlips (Plectorhinchus lineatus) New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) just swimming out of mouth of Oblique / Diagonal banded sweetlips (Plectorhinchus lineatus) whilst cleaning / feeding, New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) just swimming out of mouth of Oblique / Diagonal banded sweetlips (Plectorhinchus lineatus) whilst cleaning / feeding, New Caledonia. Pacific Ocean.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Spotted unicornfish (Naso brevirostris) Palau. Philippine Sea.

Pascal Kobeh / Diagonal-banded / Yellowbanded sweetlips (Plectorhinchus lineatus) cleaning Spotted unicornfish (Naso brevirostris) Palau. Philippine Sea.

Pascal Kobeh / Blue streak cleaner wrasse (Labroides dimidiatus) cleaning Mappa pufferfish (Arothron mappa) Palau. Philippine Sea.

Pascal Kobeh / Honeycomb moray (Gymnothorax favagineus) having its mouth cleaned by a common cleanerfish (Labroides dimidiatus), Daymaniyat islands, Oman. Gulf of Oman.

Pascal Kobeh / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning Titantriggerfish (Balistoides viridescens) Maldives. Indian Ocean.

Denis-Huot / Yellow-billed oxpecker (Buphagus africanus) cleaning a African buffalo (Syncerus caffer) Masai Mara Game Reserve, Kenya

Denis-Huot / Yellow-billed oxpecker (Buphagus africanus) cleaning a African buffalo (Syncerus caffer) Masai Mara Game Reserve, Kenya

Michael Pitts / Giant manta ray (Manta birostris) swimming over a cleaning station, Maldives, Indian Ocean.

Alex Mustard / Giant moray (Gymnothorax javanicus) emerges from crack in coral reef and is cleaned by cleaner wrasse (Labroides dimidiatus) Ras Mohammed Marine Park, Sinai, Egypt. Red Sea.

Solvin Zankl / Giant manta rays (Manta birostris) at cleaning station North Raja Ampat, West Papua, Indonesia, Pacific Ocean

Solvin Zankl / Humpback / Northern / Scarlet cleaner shrimp (Lysmata amboinensis) cleaning the mouth of a Banana fusilier (Pterocaesio pisang) Raja Ampat, West Papua, Indonesia, Pacific Ocean.

Doug Perrine / Reef manta rays (Manta alfredi) at a cleaning station on a coral reef between Makalawena and Mahaiula to have parasites removed by wrasses, Kona Coast, Hawaii, USA. Central Pacific Ocean.

Tui De Roy / Small Ground-Finch (Geospiza fuliginosa) feeding on skin parasites of Marine Iguana (Amblyrhynchus cristatus), Santa Cruz Island, Ecuador

Tui De Roy / Small Ground-Finch (Geospiza fuliginosa) feeding on skin parasites of Marine Iguana (Amblyrhynchus cristatus), Santa Cruz Island, Ecuador

Fred Bavendam / Elongate Surgeonfish (Acanthurus mata), light and dark morphs, being cleaned by juvenile Redfin Hogfish (Bodianus dictynna) and Blackspot Cleaner Wrasse (Labroides pectoralis), Bali, Indonesia

Fred Bavendam / Elongate Surgeonfish (Acanthurus mata) pair being cleaned by juvenile Redfin Hogfish (Bodianus dictynna) and Blackspot Cleaner Wrasse (Labroides pectoralis), Bali, Indonesia

Fred Bavendam / Elongate Surgeonfish (Acanthurus mata) school being cleaned by juvenile Redfin Hogfish (Bodianus dictynna) and Blackspot Cleaner Wrasses (Labroides pectoralis), Bali, Indonesia

Fred Bavendam / Indian Ocean Oriental Sweetlips (Plectorhinchus vittatus) being cleaned by Blue-streaked Cleaner Wrasse (Labroides dimidiatus), Bali, Indonesia

Fred Bavendam / Eyepatch Butterflyfish (Chaetodon adiergastos) and Indian Ocean Oriental Sweetlips (Plectorhinchus vittatus) group waiting while Flame Goatfish (Mulloidichthys vanicolensis) is being cleaned by Blue-s...

Fred Bavendam / Indian Ocean Oriental Sweetlips (Plectorhinchus vittatus) being cleaned by Blue-streaked Cleaner Wrasse (Labroides dimidiatus), Bali, Indonesia

Franco Banfi / Ocean Sunfish (Mola mola) with Longfin bannerfish (Heniochus acuminatus) cleaning the skin, Crystal Bay, Nusa Penida, Bali Island, Indonesia, Pacific Ocean

Doug Perrine / Green sea turtle (Chelonia mydas) being cleaned by yellow tangs (Zebrasoma flavescens) at a cleaning station where the turtles are groomed by the fish in a mutualistic, symbiotic relationship, Puako,...

Martin Willis / Cape Buffalo (Syncerus caffer) male with Red-billed Oxpecker (Buphagus erythrorhynchus) on nose, Kruger National Park, South Africa