Lurking among rocks on the Antarctic Peninsula, the most aggressive land predator on the frozen continent is on the prowl -for microscopic prey.
Animals such as lions, crocodiles or snakes thrive elsewhere on the planet, but Antarctica's most fearsome land predator is a reddish bug.
The continent is best known for penguins, seals and whales, but all rely on the sea for food, unlike its Lilliputian land-based creatures and plants - so far almost unaffected by humans.
Scientists are stepping up their study of these tiny creatures in Antarctica for possible early warnings about how climate change may disrupt life around the planet in coming decades.
"Antarctica is strikingly different to other continents in terms of what you find on land," Pete Convey, a biologist at the British Antarctic Survey, said while peering at an apparently barren pile of rocks on the Antarctic Peninsula.
"There are no land mammals, there are no grazing animals like gazelles, no land birds," near the British Rothera Base he said. One of the first rocks he picked up had a tiny, reddish mite racing around the surface.
"It's the lion of the ecosystem - it's the top predator," he said of the Rhagidia mite, about one mm across. The mites have eight millimetre and are related to spiders.
The biggest land animal on the entire continent, which covers more land than the US, is a flightless midge about 0.5 cm long.
Such tiny animals have found ways to live year-round on land and shut down their bodies to survive the deep winter freeze.
The simplicity of the ecosystem means the impact of new threats such as climate change can be more easily assessed.
"There are only two (land) predators within 500 miles of here," Dr Convey said. "It makes it a lot easier to understand the way the ecosystem func-tions."
"Everywhere people go they take roads, they take pollution, they take farming, they move species around," said David Vaughan, a glaciologist at BAS.
"It's very hard to see how climate change affects a natural ecological system, except somewhere like this," he said of the Rothera area, ringed by mountains and icebergs crowding the bay.
"The Antarctic Peninsula, because the climate is warming so rapidly, is the one place on the world's surface where you can come to see the effects on the ecology in a pure form," he said.
The peninsula, sticking up toward the southern tip of South America, is the part of the southern hemisphere that has warmed fastest in the past 50 years, apparently because of an increase in temperature stoked by human use of fossil fuels.
Temperatures on the Antarctic Peninsula have risen by three Celsius in the past half century, almost the difference in mean annual temperatures between France's southern city of Nice and Paris.