– THE WHALE –
Whales belong to a group of mammals called catecea. Unlike fish, they are mammals; that is, they are air-breathing, warm-blooded animals which nourish (feed) their young with milk. Their sizes vary from the small porpoise whale – less than 1.5 metres long – to the largest animal that has ever lived on earth – the blue whale. It can exceed 30 metres in length and 150 tonnes in weight. If such a whale accidentally swam ashore and were unable to get back to the sea, it would be crushed to death by its own weight.
The whale looks like a fish but there are important differences in its external structure. Its tail consists of a pair of large, flat, horizontal paddles, whereas the tail of a fish is vertical. Fish breathe the oxygen dissolved in water through their gills. Gills are found on both sides of the head and contain blood vessels which pick up oxygen as water passes through them.
Unlike fish, whales have lungs and, for this reason, have to come to the surface to breathe in or release air. Most large whales can stay underwater for up to 20 minutes. The sperm whale, however, is an exception. It can dive to 3000 metres and stay below for more than an hour. Unlike fish, whales have blow holes, or nostrils, on top of their large heads. A whale breathes out through this blow hole. When the breath is released, it condenses in the air making a cloud of moisture or a spout.
The whale’s skin is almost hairless, smooth and shiny and it covers a thick layer of fat called ‘blubber’. This is up to 30 cm in thickness and serves to conserve heat and body fluids. The eyes seem very small compared to its huge body. Nevertheless, whales have very good vision. They have no external ears, yet their hearing is excellent.
There are two main groups of whale: toothed and toothless. The former includes the dolphin, the porpoise, the killer whale and the sperm whale.
Some examples of the latter are the grey, the humpback, the right and the blue whales. Toothed whales have rows of carved teeth which they use to grasp their food. Some large toothed species, like the killer, feed on other large mammals such as the porpoise while others- e.g. the sperm whale – eat smaller forms of marine life like octopuses and squids.
The toothless whales, or ‘baleen whales’, have no functional teeth. Instead, they have brushy plates of whalebone called ‘baleen’ hanging from the upper jaw. These strain small fishes from the water. In other words, these whales feed on marine animals that are caught by a filtering process. Their diet consists mainly of ‘krill’, which can be found in masses in the oceans cf the world.
Whales live in oceans throughout the world, they travel in schools-, that is, in groups, and often migrate thousands of miles.
The whale has been hunted by man for many centuries mainly for its blubber. This substance is used in cosmetics, the manufacture of margarine and the softening of leather. The waxy substance called ‘spermaceti’, which is found in the head of a sperm whale, for instance, is used to make soap. ‘Ambergris’, another waxy substance found in every whale’s intestine, is used in the manufacture of perfume, where it serves to improve the scent.
The whale has also been hunted for its meat, which is eaten by both humans and animals. In fact, in Japan it has been a major source of protein for many centuries. The commercial value of the whale has led to a serious decrease in the whale population and it is unfortunate that in the near future, extinction of some types of whales seems inevitable.
THE WHALES’ LENGTH
A. Mark the statements as True (T) or False (F).
1. The smallest whale is the porpoise whale.
2. Most whales can stay underwater for more than an hour.
3. Blubber is a layer ot fat that covers the skin of a whale.
4. Porpoises eat sperm whales, octopuses and squids.
5. The grey whale is a member of the baleen group.
6. ‘Krill’ is part of a whale’s body.
7. Whales prefer to live alone.
8. ‘Spermaceti’ and ‘ambergris’ are waxy substances found in all whales.
9. Whale meat is used in the production of animal food.
10. All whales will soon become extinct.
B. Fill in each box with one word only.
Differences Between the Fish and the Whale
position of the tail
organs for breathing
C. Use words from the passage to complete the following chart.
the right whale
D. Fill each blank with a suitable adjective that describes each item.
Physical features of the whale:
skin: • . -.• — • i
eyes:, vision: hearing: