Juergen Freund / Manta rays (Manta birostris) at cleaning station being cleaned by wrasses, Moluccas Islands, Indonesia.

Juergen Freund / Decorator crab (Dorippe frascone) with an Upside down jellyfish (Cassiopea andromeda) on its back. The jellyfish is bigger than the crab! Palawan, Philippines.

Alex Mustard / Manta rays (Manta birostris) at a cleaning station. Raja Ampat, West Papua, Indonesia. Tropical West Pacific. March

Alex Mustard / A Black Manta ray (Manta birostris) hovers above a cleaning station on a coral reef. Raja Ampat, West Papua, Indonesia. March

Alex Mustard / Manta rays (Manta birostris) at a cleaning station. Raja Ampat, West Papua, Indonesia. Tropical West Pacific. March

Alex Mustard / A Manta ray (Manta birostris) unfurls its cephalic fins at a cleaning station. Raja Ampat, West Papua, Indonesia. Tropical West Pacific. March

Tim Laman / Bluestreak cleaner wrasse (Labroides dimidiatus) cleaning a Spotted Porcupinefish (Diodon hystrix) on a coral reef in Bali, Indonesia.

Georgette Douwma / Humphead wrasse (Cheilinus undulatus) attended by two Cleaner wrasses (Labroides dimidiatus). Komodo, Indonesia. Indo-Pacific.

Juergen Freund / Grey faced moray eel and cleaner fish {Siderea thyrsoidea} Indo-pacific

Juergen Freund / Potato grouper {Epinephelus tukula} with mouth being cleaned by Cleaner wrasse {Labroides dimidiatus} Great Barrier Reef & Coral Sea, Australia

Juergen Freund / False clown anemoonefish in anemone {Amphiprion ocellaris} Indo-Pacific.

Peter Blackwell / Yellow billed oxpecker (Buphagus africanus) on the back of a buffalo, Masai Mara, Kenya