When ground is soft in the summer, the bottoms of the animal's hooves act like sponges to provide traction(牵引力),while the rim(边缘) of the hoof becomes exposed in the winter.
This means that they can cut into ice and snow to stop them from slipping. They even use them to dig down through hard snow so they can find their favorite food—a lichen known as reindeer moss.
The vision of reindeer may also outperform a snowmobile's lights, because the animals can see ultraviolet light.
Snow reflects up to 90 percent of UV light and this ability helps the animals to see clearly in dim lighting and landscapes that are largely white, where may objects blend unto the landscape.
Things like fur and urine, for example, show up clearly in ultraviolet light, compared to what humans see.
A study by University College London(UCL) revealed in 2011 that reindeer can see light with wavelengths as short as 320 nanometers(nm), considerably below the human threshold of 400 nm.
Researchers from the University of Troms discovered that the eyes of reindeer change color according to the seasons too.
While it may seem funny that policemen could use reindeer like a police car, the country's navy already uses animals to enforce rules.
The Russian Defense Ministry uses donkeys to patrol(巡逻) the country's mountain ranges, while the Navy employed the help of dolphins to enable them to detect underwater mines.
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