Ammonite / Earthworm (Lumbricus terrestris) moving through leaf litter, footage taken using an endoscopic camera in controlled conditions, Bristol, England, UK, June.

Martha Holmes / Detail of Hippopotamus skin showing oily secretion {Hippopotamus amphibius}

Tony Wu / Korean sandlance (Hypoptychus dybowskii) egg clusters on Sargassum (Sargassum horneri). Fish produce sticky secretion in kidneys that adheres eggs to Sargassum. Hokkaido, Japan. May.

Eric Baccega / Common hippopotamus (Hippopotamus amphibius). Skin with secretion of blood sweat, a red substance that acts as natural sunscreen. Beauval Zoo Parc, France. Captive.

Eric Baccega / Common hippopotamus (Hippopotamus amphibius). Skin with secretion of blood sweat, a red substance that acts as natural sunscreen. Beauval Zoo Parc, France. Captive.

Eric Baccega / Common hippopotamus (Hippopotamus amphibius), close up of eye. Skin spotted with secretion of blood sweat, a red substance that acts as natural sunscreen. Beauval Zoo Parc, France. Captive.

Eric Baccega / Common hippopotamus (Hippopotamus amphibius), close up of eye. Skin spotted with secretion of blood sweat, a red substance that acts as natural sunscreen. Beauval Zoo Parc, France. Captive.

Yashpal Rathore / Asiatic elephant (Elephas maximus) male in musth grazing, with secretion of musth from temporal gland near ear visible. Jim Corbett National Park, India.

Yashpal Rathore / Asiatic elephant (Elephas maximus), male with musth secretion from temporal gland near ear visible. Jim Corbett National Park, India.

Ammonite / Earthworm (Lumbricus terrestris) secreting lubricating mucus before moving away from camera, footage taken using an endoscopic camera in controlled conditions, Bristol, England, UK, June.

Charlie Summers / African elephant (Loxodonta africana), close up of face showing patch of secreted hormone, a sign that the animal is in musth, Ngorongoro Crater, Tanzania, East Africa

Charlie Summers / African elephant (Loxodonta africana) close up of face showing a patch of secreted hormone, a sign that the animal is in musth, Ngorongoro Crater, Tanzania

Alex Hyde / Detail of enormous inflorescence of Arum (Amorphophallus sp) showing droplets of foul-smelling secretion on spadix that attract pollinating insects. Kirindy forest, West Madagascar

Alex Hyde / Detail of spadix from enormous inflorescence of Arum (Amorphophallus sp) showing droplets of foul-smelling secretion that attract pollinating insects. Kirindy forest, West Madagascar

PREMAPHOTOS / Caterpillar larva of King swallowtail butterfly (Papilio sp) resembling a bird dropping, extruding its osmaterium which releases a foul smelling secretion, rainforest, Panama

PREMAPHOTOS / Caterpillar larva of King swallowtail butterfly (Papilio sp) resembling a bird dropping, extruding its osmaterium which releases a foul smelling secretion, rainforest, Venezuela

PREMAPHOTOS / Leafhoppers (Rhaphirrhinus phosphoreus) sucking sap from a rainforest tree and exuding honeydew on to the leaf from their rear ends, Peru

PREMAPHOTOS / Caterpillar larva of lycaenid blue butterfly (Narathura sp). The green tree ants (Oecophylla smaragdina) protect the caterpillar which provides them with a sweet secretion as a reward, rainforest, Aus...

Nature Production / Spear / Bleeker's Squid {Loligo bleekeri} larva secreting ink, captive, Japan

John Cancalosi / Leaf frog on reed {Phyllomedusa bicolor}, toxic skin secretion, Peru, South America

Kim Taylor / Male Three spined stickleback {Gasterosteus aculeatus} uses sticky secretion to cement nest, Sequence 9/16

Mark Moffett / Embera Choco people use a distinctive kind of blowgun and secretion from Golden Poison Dart Frog (Phyllobates terribilis) to poison on their darts for hunting, Colombia

Bernard Castelein / Common sundew {Drosera rotundifolia}, Kalmthoute, Belguim.

Nigel Cattlin / Cuckoo spit from Green / Meadow froghopper, (Philaneus spumarius) on lavender stems, Berkshire, June

Paul Bertner / Ant (Formicidae) feeding on nectar secretion, Tambopata Research Center, Peru

Martha Holmes / Detail of Hippopotamus (Hippopotamus amphibius) skin showing oily secretion. Semi-captive hippo.

Nick Upton / Common yellow-faced bee (Hylaeus communis) nest burrow in an insect hotel, partially sealed up with a cellophane-like secretion, Wiltshire garden, UK. July.

Tony Wu / Korean sandlace (Hypoptychus dybowskii) fish eggs freshly spawned and attached to Sargassum (Sargassum horneri) by a sticky secretion, Japan, Pacific Ocean.

Nigel Cattlin / Cytospora canker (Cytospora leucostoma) canker disease exudation from a peach tree trunk, USA, September

Nigel Cattlin / Severe bacterial blight Pseudomonas syringae) gummosis exudation on the trunk of a crop peach tree

Nigel Cattlin / Secretions of Olive psyllid (Euphyllura olivine) on Olive (Olea europaea) leaves and twigs. Greece.

Nigel Cattlin / Honeydew and soft brown scale insects (Coccus hesperidum) on a banana leaf midrib vein, a house plant.

Nigel Cattlin / Honeydew and soft brown scale insects (Coccus hesperidum) on a banana leaf midrib vein grown as a house plant,