Lucas Bustamante / Amazonian millipede with parasites. Sumaco National Park, Napo, Ecuador

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), feeding on marine iguana parasites and dead skin, Galapagos

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 / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

David Fleetham / Green Sea Turtles (Chelonia mydas) gathering at a cleaning station off where small fish will remove their parasites. West Maui, Hawaii.

Jaymi Heimbuch / Yellow-billed Oxpecker (Buphagus africanus) picking parasites off of Cape Buffalo (Syncerus caffer), Masai Mara, Kenya

Solvin Zankl / Gall wasp (Cynips quercusfolii) emerging from the oak gall. Germany, October.

Juergen Freund / Paralytic tick (Ixodes holocyclus) with engorged body on human hand, this species affects many species, Spectacled flying fox (Pteropus conspicillatus) among them and infects them with a toxin that ca...

Alex Mustard / Red eye medusa (Polyorchis penicillatus) with hitchhiking amphipods (Hyperia medusarum). Browning Pass, Vancouver Island, British Columbia, Canada. North East Pacific Ocean.

Heini Wehrle / Red-billed Oxpecker (Buphagus erythrorhynchus) pair searching for parasites on Impala, Mpumalanga, South Africa

David Tipling / 2020VISION / Reed warbler (Acrocephalus scirpaceus) with twelve day old Cuckoo (Cuculus canorus) chick at nest, Norfolk, England, UK, May

Piotr Naskrecki / Yellow Fever Mosquito (Aedes aegypti) female feeding on human blood, Gorongosa National Park, Mozambique