Nigel Cattlin / Itchgrass (Rottboellia cochinchinensis) prop / brace roots elevating plant above soil. An agressive weed of crops particularly in tropical and sub-tropical climates.

Nigel Cattlin / Itchgrass (Rottboellia cochinchinensis) prop / brace roots elevating plant above soil. An agressive weed of crops particularly in tropical and sub-tropical climates.

Nigel Cattlin / Itchgrass (Rottboellia cochinchinensis) unopened flower spikes. An agressive weed of crops particularly in tropical and sub-tropical climates.

Ashley Cooper / Midge bites on a man

Ammonite / Female Topi (Damaliscus lunatus) and calf scratching and suckling, with another calf grooming itself nearby and a third lying down in the grass, Masai Mara, Kenya.

Jabruson Motion / Group of African forest elephants (Loxodonta africana cyclotis) feeding, drinking and interacting at a mineral pool, Dzanga-Ndoki National Park, Sangha-Mbaere Prefecture, Central African Republic

Lou Coetzer / Baby African elephant (Loxodonta africana) rubbing an itch against its mother's leg, Chobe River, Botswana, April, Vulnerable species.

Roger Powell / Reindeer (Rangifer tardus) rubbing its velvet antlers on vegetation. Porsanger interior, Finmark, Norway, June.

Dave Watts / Common Wombat (Vombatus ursinus) adult scratching, Tasmania.

Christophe Courteau / Walrus (Odobenus rosmanus) scratching, Poolpynten, Svalbard, Norway, June 2012.

Solvin Zankl / Bat-eared fox (Otocyon megalotis) scratching face, Namib-Naukluft National Park, Namib Desert, Namibia.

Jabruson / Young wild Chimpanzee (Pan troglodytes schweinfurthii) Tongo, Virunga National Park, Kivu, Democratic Republic of Congo

Eric Baccega / Male Steller sea lion (Eumetopias jubatus) scratching, with a group of females hauled out at a rookery, Prince Rupert, British Columbia, Canada, June.

Eric Baccega / Male Steller sea lion (Eumetopias jubatus) scratching, with a group of females hauled out at a rookery, Prince Rupert, British Columbia, Canada, June.

Mark Taylor / Black-and-white tuxedo male kitten, 'Tuxie' aged 3 months, using a scratching post.

Anup Shah / Proboscis monkey (Nasalis larvatus) young male sitting in the forest canopy scratching, Bako National Park, Sarawak, Borneo, Malaysia, April

Petra Wegner / Blenheim Cavalier King Charles Spaniel wearing a protection funnel / Elisabethan collar to stop it from scratching

Petra Wegner / Jack Russell Terrier scartaching its neck

Petra Wegner / Tricolor Cavalier King Charles Spaniel wearing a protection funnel / Elisabethian collar to stop it from scratching

Petra Wegner / Jack Russell Terrier sitting and scratching

John Cancalosi / Alpine Ibex {Capra ibex ibex} using antler to scratch backside, Switzerland

Pete Oxford / African elephant (Loxodonta africana) with an itch rubbing his body on a termite mound. Makalolo Plains, Hwange National Park, Zimbabwe, Southern Africa

Pete Oxford / African elephant (Loxodonta africana) with an itch rubbing his body on a termite mound, Makalolo Plains, Hwange National Park, Zimbabwe, Southern Africa

Jane Burton / Merle Collie-cross pup with mange, scratching her chest.

Jane Burton / Merle Collie-cross pup with mange, scratching her neck.

Mike Potts / Grey seal {Halichoerus grypus} scratching face, Bardsey island, Gwynedd, Northern Wales, UK

Hanne & Jens Eriksen / Western Reef Heron {Egretta gularis} scratching, Barr Al Hikman, Oman.

Tom Vierus / Galapagos sea lion (Zalophus wollebaeki) lying on a rock and basking in the sun. The sea lion uses the rock to scratch an itch on its neck. The animal is trying to rest but it is being disturbed by fl...