Dragging a sleigh loaded with enough presents for the world’s children can be no easy skill. But, since ancient times, the Christmas Eve duty has been performed by a team of beloved reindeer.

Soon, however, Santa Claus may have to start looking around for a stronger type of animal, as newresearch shows the species is becoming increasingly puny. A 16-year survey on the arctic Norwegian islands, Svalbard, found the reindeer there have declined in weight by an alarming 12 percent.

The reduction in average body weight is being blamed on global warming. In the research presented lately at a meeting of the British Ecological Society in Liverpool, scientists have explained how upward temperatures are robbing female reindeer of nutrients during important periods of pregnancy.

Snow in Svalbard typically covers the ground for eight months of a year, which, combined with low temperatures, limits grass growth to June and July. But as summer temperatures increase by around 1. 5℃, grass has become more productive, allowing female reindeer to gain more weight by autumn and therefore to have more babies. However, winters have brought with them greater rainfall which freezes when it settles on the snow. Reindeer can often access the poor food sources beneath the snow by clearing it away with their antlers (鹿角) , but they cannot break through the hard ice. As a result, female reindeer are becoming starved, causing them to lose their babies or give birth to the much lighter young.

Despite the findings, reindeer appear to be suffering less from the effect of climate change than some other arctic species. Last week the scientists warned that a third of the world’s polar bears could disappear in the next 40 years.

   The sea is home to billions of plants and animals. Many live only near the sunlit surface. Oceanographers sort marine (海洋的) living beings by dividing them into two main groups: plants and animals.

There are two general types of plants found in the ocean, those having roots that grow in the ocean bottom and those not having roots which simply float around with water. The rooted plants in the ocean are only found in shallow waters because there is not enough sunlight to maintain photosynthesis (光合作用) in deeper waters. Since sunlight does not pass more than a few hundred feet into the ocean, most of the ocean is unable to support rooted plants.

The most plants in the ocean are known as phytoplankton (浮游植物群落) . These are usually single-celled, small floating plants that float throughout the surface waters of the ocean. To grow, phytoplankton need nutrients from the sea water and lots of sunlight.

Marine animals are divided into three groups: zooplankton, nekton, and benthos. Zooplankton are floating animals and are usually small; however, they can grow to fairly large size. The jellyfish and the Portuguese man-of-war are examples of larger types of zooplankton which are unable to move themselves effectively.

Nekton are the free swimmers and probably the largest part of familiar animals found in the ocean belong to this class. Common fishes, octopuses, whales, eels and squid are all examples of nekton.

The third type of sea animals spends their entire life on the bottom of the ocean. This group of marine animals is called benthos. Some of these creatures, such as lobsters and snails, may be able to move about on the bottom but their lifestyle is so closely linked with the ocean floor that they are unable to survive away from this environment.

   Penguins are the number-one attraction for many visitors to Antarctica. If you go on a ship that is allowed to make shore landings, you may see them. But to get a close look at penguins, you have to be smart.

First of all, keep in mind that Antarctica’s visitor rules require that you remain at least five meters away from the penguins in order not to disturb them. You could easily become responsible for the death of a little penguin or the destruction of an egg if your too-close presence should disturb a penguin parent.

If a penguin is trying to move away from you, you must stop what you’re doing and back off even if you’re farther than five meters away. However, the rules don’t prevent a curious penguin from approaching within five meters of you — as long as the bird makes the move, not you.

Little penguins, in particular, are quite curious. I’ve seen several lucky tourists who were astonished to find that little penguins came right up to them. If a penguin comes extremely close to you, remember that you are not allowed to touch or hold it.

Here are more tips for getting close to penguins.

Ignore the smell: where penguins live is filled with guano（海鸟粪）and the smell takes some getting used to.

Be quiet because loud noises make penguins nervous. Fast or sudden movements signal meat — eating animals to penguins, and they react accordingly, so slow down when you walk around them.

Since it may take half an hour or more before the penguins get used to you, you need to be patient. Put away your camera — too often people are so focused on getting the pictures that they forget to look with their own eyes, but most of your most memorable experiences in Antarctica will be marked in your mind, not on a roll of films.

Last year I 【小题1】 (work) in Nepal for three months. When I had a few days off，I decided 【小题2】 (go) into the jungle (丛林) . I asked a Nepalese guide，Kamal Rai to go with me.

We started our trip at six in the morning with two elephants 【小题3】 (carry) our things. It was hot, but Kamal made me wear shoes and trousers to protect me 【小题4】 snakes. In the jungle there was a lot of wildlife, but we were trying to find tigers. We climbed onto the elephants' backs to see better. However, 【小题5】 is unusual to find tigers in the afternoon because they sleep in the daytime.

Then, in the 【小题6】 (distant), we saw a tiger, and Kamal told me to be very quiet. We moved nearer and found a dead deer, 【小题7】 was the tiger's lunch! Suddenly, I started to feel very 【小题8】 (frighten), then a huge tiger jumped out suddenly. It caught Kamal's leg between its teeth, but I managed to pull Kamal away. One of our 【小题9】 (elephant) ran at the tiger and made it go back into the grass, so we 【小题10】 (quick) ran away.  That night it was impossible to sleep!