The week in wildlife

Shelby County, US: A yellow bear caterpillar makes its way across Houston Road Photograph: Erin Pence/Sidney Daily News/AP

Kincraig, UK: Yuri and Sasha, a pair of rare Amur tigers get fed at their new home, the Highland wildlife park. With only 500 remaining in the wild, it is hoped that the pair will continue to contribute to the worldwide breeding programme, which acts as a safety net against extinction Photograph: Jeff J Mitchell/Getty

Bangkok, Thailand: Two conjoined Nile tilapia fish. The bigger fish tends to protect the smaller one from harm while the smaller one looks for food at the bottom of the aquarium Photograph: Sukree Sukplang/Reuters

Temple, Texas: An adult monarch butterfly probes for nectar on a Gregg's mistflower. The smaller queen butterfly mimics the monarch's colouring to fool predators into thinking that it, like its larger cousin, is also toxic. Monarch larvae eat the sap of milkweed to give the adult its toxic flavour Photograph: Scott Gaulin/The Daily Telegram/AP

Sharifabad, India: Cattle grazing on the bank of a canal Photograph: Fayaz Kabli/Reuters

Andasibe, Madagascar: An indri lemur feeds on foliage in a primary forest at a natural reserve. Conservation of lemurs is a high priority, but the country's poor economic situation and the lemurs' limited range make it an uphill battle Photograph: Roberto Schmidt/AFP

Debrecen, Hungary: Laszlo Szakal of the Hungarian Society of Ornithology prepares to take a blackbird out of a net caught on European bird observation day in the Botanical Garden of the University of Debrecen Photograph: Tibor Olah/EPA

Encinitas, US: A lizard crawls down a window screen Photograph: Mike Blake/Reuters

Kashgar, China: Sheep for sale at the Sunday livestock market Photograph: Diego Azubel/EPA

Rhyl, UK: A seagull flies past a telescope Photograph: Christopher Furlong/Getty

Puerto Montt, Chile: Salmon are washed before being processed at the Marine Harvest seafood factory Photograph: Francisco Negroni/AFP

Tissues of a mouse embryo labelled with a green fluorescent protein and a red fluorescent protein. Green fluorescent protein (GFP) is one of the most important tools biologists use for investigating how the molecular machinery in cells operates Photograph: Gloria Kwon, Kat Hadjantonakis/MSKCC/AP

Rio de Janeiro, Brazil: Penguins, which had been kept at an animal rehabilitation centre, onboard a Brazilian navy ship. More than 30 penguins that mysteriously washed up on Brazil's equatorial beaches were sent to Rio Grande do Sul state to be released into the ocean Photograph: Ricardo Moraes/AP