Alex Mustard,Alex Mustard / Red eye medusa (Polyorchis penicillatus) with its feeding tentacles extended to catch planktonic prey. Note that the bell of the jelly has hitchhiking amphipods (Hyperia medusarum). Browning Pass, Van...

Bence Mate / Common cuckoo chick (Cuculus canorus) begging for food from Great reed warbler (Acrocephalus arundinaceus) foster parent, Pusztaszer, Kiskunsagi National Park, Hungary

Bence Mate / Common cuckoo chick (Cuculus canorus) begging for food from Spotted flycatcher (Muscicapa striata) Pusztaszer, Kiskunsagi National Park, Hungary

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

Franco Banfi / Southern right whale (Eubalaena australis) with patches covered in parasitic crustaceans named cyamids or whale lice (Cyamus ovalis). Golfo Nuevo, Peninsula Valdes, UNESCO Natural World Heritage Site,...

Franco Banfi / Southern right whale (Eubalaena australis) with calluses covered in parasitic crustaceans named cyamids or whale lice (Cyamus ovalis). Golfo Nuevo, Peninsula Valdes, UNESCO Natural World Heritage Site...

Franco Banfi / Southern right whale (Eubalaena australis) with patches covered in parasitic crustaceans named cyamids or whale lice (Cyamus ovalis). Golfo Nuevo, Peninsula Valdes, UNESCO Natural World Heritage Site,...

Aflo / Composite image of tick showing how its body expands after feeding

Juergen Freund / Spectacled flying fox (Pteropus conspicillatus) casualty of paralytic tick (Ixodes holocyclus) bite being cared for on site of colony by Jenny Mclean, North Queensland, Australia, November 2012

Alex Hyde / Human Head Louse (Pediculus humanus capitis) macro shot of claw, that allows the louse to grip onto the hairs of their human host, False-colour scanning electron micrograph (SEM).

Paul D Stewart / Male Large Blue Butterfly (Maculinea eutryphon / arion) collected in 1865. It is here surrounded by other extant UK blue butterfly species. The large Blue was first recorded as a British species in 17...

Tui De Roy / Volcan Alcedo giant tortoises (Chelonoidis nigra vandenburghi) wallowing in rain pools on caldera floor, possibly for thermoregulation or detering parasites, with sulphur fumaroles in background, Alce...