英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—11（在线收听） |
Thousands of years of isolation turned them into a separate species. In the middle of the lake are the Ushkanyi islands. Here the seals form their colonies safe from human predation. After a dip in the lake, nothing beats a dry resting place on the lake-side rocks. Getting onto them / is by no means easy using flippers. But underwater, they are hydrodynamic torpedoes, zipping along at up to 25 kilometers per hour. The oldest and deepest lake in the world, over 1.5 kilometers, originated more than 20 million years ago when two tectonic plates drifted apart. They are still separating at about six millimeters a year.
Down here, the Baikalian sponge colony resembles a coral reef. It can even survive under complete ice cover. Sixty percent of the creatures found here are unique to the lake. While some animals are tiny, the oxygen-rich water enables extreme growth in others. Some amphipods in Baikal can reach 90 millimeters. Deep in the lake, life and death quietly play out. Snails clean up a rotting fish. Others are busy mating in the cold waters.
Fifty stories up on the surface, Baikal prepares for an invasion – caddis flies. |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2011/259571.html |