What are the characteristics of whales?

Whales are marine mammals, viviparous, nursing their young and breathing with their lungs. But it is not only different from marine mammals such as seals, but also different from seabirds such as penguins that breathe with their lungs. It lives in water all its life, while other marine mammals and seabirds live in water for some time and on land for some time. This special habit may be related to its origin.

Being good at swimming and diving is one of the common habits of whales and other marine mammals. Whales and seals are excellent divers. The swimming speed of baleen whales is generally 30 kilometers per hour, and it is 40 kilometers per hour when they are scared. Whales have the fastest speed, about 55 kilometers per hour, which is faster than a 10,000-ton ship. Sperm whales swim very slowly, usually every hour 10 km, and the fastest is 25 km. The time and depth of whale diving are also amazing. Can dive 200 ~ 300 meters deep for 2 hours. Compared with seals, whales can't dive as deep as Weddell seals. Weddell seals can dive 600 meters, but whales can dive much longer than seals. Weddell seals dive for 70 minutes, only half as much as whales. This difference between deep diving and long diving may be related to different body sizes. Whales are huge, and their movements when diving and floating are obviously not as flexible as those of the slender and strong Weddell seal. The whale has a large lung capacity, its lungs can hold 15000 liters of gas, it stores a lot of oxygen when diving, and it exhales a lot of carbon dioxide when floating, which is one of the mysteries of its long-term diving. In addition, whales and seals have very small heads, less than11000 of their body weight, which may be an advantage for them to dive for a long time.

Fountain breathing is a unique life habit of whales. When whales live underwater, they close their nostrils and breathe out of the water. When they breathe, their nostrils open, and with the pressure of the lungs and the contraction of muscles, they spray a sparkling water column, accompanied by a whistle-like cry. The height and shape of spray column is a sign to identify different whale species. Based on this, experienced whalers can quickly judge the species, size and distance of whales. For example, the blue whale's water jet column is vertical and powerful, thick on the top and thin on the bottom, loose on the top, like a fireworks show, with a range as high as 10 meter. Other baleen whales generally have a water jet column height of 8 ~ 10 meter. Sperm whale's water jet column is deflected to the left and front, and its jet force is weak, short and loose, and its height is only 3 ~ 4 meters. The cause and composition of water column are still controversial. Some people think that it is the waste discharged from the lungs, while others think that it is the product of the combination of water vapor in the lungs and seawater.

Whales in the Southern Ocean mainly feed on krill, but also eat some crustacean zooplankton, such as copepods. Filter-feeding baleen whales migrate from subtropical and temperate zones to the South Pole, where they feast and mate. During this period, some people can accumulate 50% body fat. Baleen whales rarely eat in the subtropics, and the fat accumulated in Antarctica is used to provide energy for the rest of the year. Toothed whales are mainly squid and fish eaters.

Whales have a big appetite. A blue whale can eat 8 ~ 10 tons of krill a day. The mouth of a blue whale has a volume of 5 cubic meters. When it opened its mouth, a large number of krill poured in with the sea water. When it closes its mouth, the seawater is squeezed out from the gap between its lips, and the filtered krill is swallowed in one gulp.

The habit of most whales in groups is not obvious, but sperm whales have the habit of organizing small families. Their members are often female whales, young whales and male whales, but there are often adult male whales around, waiting for opportunities to compete for their wives. Sperm whales are usually polygamous.

Many whales breed outside Antarctica, usually once a year, giving birth to a calf at a time. Pregnancy is generally 9 ~ 12 months, blue whale 12 months and sperm whale 16 months. Young whales grow very fast. The fertilized eggs of blue whales weigh less than 1 mg, which is too small to be distinguished by naked eyes. At birth, the cub is 7-8 meters long and weighs about 2-3 tons. It is the biggest baby in the world today. The feeding period of larvae is 7 months, and the daily feeding amount is 400 ~ 500 kg. Mother whale's milk is rich in nutrition, and its fat content is 40% ~ 50%, which is close to that of seals and 0/0 ~/0/5 times that of fresh milk. So calves grow fast and fat. During the feeding period, calves can gain 4 kilograms per hour, but they actually gain 80 ~ 100 kilograms a day and night. After weaning, the growth rate of young whales is greatly reduced. The sexual maturity of blue whales is 4 ~ 5 years, and the longest life span can reach 100 years. The life span of baleen whales is generally 40 ~ 50 years, and the longest is 100 years.

Migratory life is the same habit of whales, just like the migration of fish and migratory birds, but the time, season and place are different. Migration is an instinct of whales and is also forced by survival. For example, fin whales rarely eat in other waters, mainly in Antarctic waters, so they must return to Antarctic waters. Most whales in the Southern Ocean migrate from subtropical and temperate zones, and arrive in Antarctic waters around 165438+ 10 every year, and stay there for 100 days, and then return in February and March of the following year. Baleen whales spend the longest time in Antarctic waters, usually more than 120 days. Some octopus whales can winter in Antarctic waters and breed in sub-Antarctic areas. Most other cetaceans look for mates and mate in Antarctica or during migration, and breed in temperate and subtropical regions. It is difficult to see young whales breastfeeding in Antarctic waters.

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