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.

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 (BAS), said while peering at an apparently barren pile of rocks on the Antarctic Peninsula.

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 1 mm (0.1 cm) across. The mites have eight legs and are related to spiders. And 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 800 km of (the British Rothera Base) here," Convey said.

David Vaughan, a glaciologist at BAS, said: "The Antarctic Peninsula, because the climate is warming so rapidly, is the one place where you can come to see the effects on the ecology in a pure form."

The peninsula, towards the southern tip of South America, is the part of the southern hemisphere that has warmed fastest in the past 50 years - temperatures have risen by 3 Celsius in the period.

Global warming "is going to make life easier for (tiny creatures on the peninsula), almost certainly," Convey said. Warmer temperatures would help plants grow, turn parts of the peninsula greener and so benefit the animals that feed on them.

Midget creatures have evolved in Antarctica wherever ground is exposed and there is fresh water in summer - temperatures around Rothera reach a maximum of about 7 Celsius in summer.

Rhagidia hunts for springtails, a primitive type of insect. The springtails live off vegetation. Sparse patches of green, black or orange lichen dot some rocks.

Many of Antarctica's animals have blood proteins that act as a natural anti-freeze. "I can come here in winter and collect them," Convey said.

(China Daily via Agencies January 14, 2009)