Blue whales are the largest animals ever known to have lived on Earth. These magnificent marine mammals rule the oceans at up to 100 feet (30 meters) long and upwards of 200 tons (181 metric tons). Their tongues alone can weigh as much as an elephant. Their hearts, as much as an automobile.
Blue whales reach these mind-boggling dimensions on a diet composed nearly exclusively of tiny shrimplike animals called krill. During certain times of the year, a single adult blue whale consumes about 4 tons (3.6 metric tons) of krill a day.
Blue whales are baleen whales, which means they have fringed plates of fingernail-like material, called baleen, attached to their upper jaws. The giant animals feed by first gulping an enormous mouthful of water, expanding the pleated skin on their throat and belly to take it in. Then the whale’s massive tongue forces the water out through the thin, overlapping baleen plates. Thousands of krill are left behind—and then swallowed.
Blue whales look true blue underwater, but on the surface their coloring is more a mottled blue-gray. Their underbellies take on a yellowish hue from the millions of microorganisms that take up residence in their skin. The blue whale has a broad, flat head and a long, tapered body that ends in wide, triangular flukes.
Blue whales live in all the world’s oceans occasionally swimming in small groups but usually alone or in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives.
Blue whales have few predators but are known to fall victim to attacks by sharks and killer whales, and many are injured or die each year from impacts with large ships. Blue whales are currently classified as endangered on the World Conservation Union (IUCN) Red List.
1. The first paragraph introduces blue whales by talking about their … .
2. Which of the following words describe blue whales as said in paragraph 1?
3. Based on the diet, blue whales are … .
4. In one swallow, how many krills are eaten by blue whales?
5. Baleen plates are plates of fingernail-like material attached to … .
A. the lower teeth
B. the lower belly
C. the upper teeth
D. the lower jaws
E. the upper jaws
6. The yellowish color on the underbelly comes from microorganisms that … on their belly skin.
7. Which paragraph tells about blue whales’ physical look?
8. Where can you find blue whales?
A. equatorial waters
B. polar waters
C. all oceans
D. Pacific Ocean
E. Atlantic Ocean