Name ______Date ______
Summer of the Shark
Shark attacks are on the rise. New research on shark behavior attempts to explain why
Sharks don't really like to bite people. A great white shark prefers a nice, chubby seal. A bull shark likes to fill up on fish or even another shark. Then why has this summer been so full of frightening news about shark attacks? That, scientists say, is a very good question.
Overall, your chances of being bitten by a shark are pretty small: You're 30 times more likely to be struck by lightning! Still, the number of shark attacks has been creeping upward for more than ten years. Last year was one of the worst on record, with 84 attacks worldwide. So far this year there have been 52. Most occurred in the waters off Florida and Australia.
Only three of this year's attacks were fatal. On September 1, a shark killed a young swimmer in Virginia. Two days later a shark killed a man off a North Carolina beach. Both attacks happened at dusk. Shark attacks usually take place in the morning and early evening. That's when most sharks hunt their prey.
A Case of Mistaken Identity?
Scientists believe that the main reason for the recent rise in attacks is simply that there are more people swimming, boogie-boarding and surfing than ever before. Volusia County, Florida, holds the national record for shark attacks because its long coastline and beaches are packed with bathers.
It's not a case of sharks preying on humans, says Dr. Robert Lea, a marine biologist. It's just humans sharing a spot in the ocean with sharks —at the wrong time.
Researchers who study shark behavior believe that most shark attacks are a case of mistaken identity. A shark might think a human foot is a flounder. Sharks usually spit out human flesh after the first bite!
Who's Threatening Whom?
Sharks are one of nature's ultimate designs: confident, sleek and deadly. Three types account for most attacks on people—great whites, tigers and bull sharks. Scientists have been using satellites to study these sharks as they move through the seas.
Great white sharks keep their blood warmer than the surrounding water. They hunt during the day. Their method of attack is to shoot up vertically from 30 feet under, knocking their prey right out of the water.
Tiger sharks hunt at night and are "willing to try anything for food," says Rocky Strong, a shark biologist.
Bull sharks are the only sharks that can live in both salt and fresh water. They have been seen swimming in the Mississippi River.
Scientists who work with sharks know how dangerous they can be. Still, they say sharks have more to fear than humans do. Fishing nets entangle and drown about 100 million sharks each year.
A Shark's Super Senses
Sharks have been swimming in the earth's oceans since dinosaurs roamed the earth millions of years ago. A close look at their bodies shows why they are such survivors. From nose to tail, they're packed with sensing equipment that helps them track down their prey.
SEEING
Like a cat, a shark can see in dim light. It must move its head from side to side to see objects directly in front of it.
HEARING
Tiny holes on top of the head lead to very sensitive ears. A shark can pick up the sound of a struggling fish 600 yards away.
SKIN
A shark's skin is covered with a protective layer of tiny, tooth like scales called denticles.
SENSING
The lateral line is a row of pores with vibration-sensitive hair cells that runs along the shark's sides. These allow a shark to sense the faintest flutter of a nearby fin. Other pores located on the head detect tiny electrical fields created by other fish.
SMELLING
A shark can smell even a tiny drop of blood in the water.
A shark's jaws contain many rows of razor-sharp teeth. When a shark takes a bite, it lifts its snout and its entire jaw slides forward. A great white's bite is so powerful it can exert pressure of 2,000 pounds per square inch.
Amazing Facts About Sharks
- You might not know these sleek, swift swimmers as well as you think. Dive into these surprising facts:
- Sharks are one of the oldest animals on Earth. They evolved over 400 million years ago, before the first dinosaurs. They have changed very little in that time.
- There are more than 370 species of sharks, and about half of them are less than 3 feet long when fully grown.
- Sharks have a keen sense of smell. Scientists estimate that scent detection makes up about 70 percent of a shark's total brain activity!
- Some sharks, such as the reef and bull shark, have color vision that attracts them to bright orange and yellow shades. Shark-savvy scuba divers avoid these colors, calling them "yum-yum yellow."
- The inside of a shark's jaw has many rows of teeth. These rows usually lie flat until the first tooth in front falls out. It is then replaced by another tooth popping forward to replace it, as if on a conveyor belt. This process of teeth replacement continues throughout a shark's life, so it has a lifetime supply of chompers!
- Sharks do not chew their food. Instead, they swallow their bites whole. A big meal, such as a sea lion or turtle, may fill up a shark for over a month.
- Cartilage, the tough, flexible material that makes up a shark's skeleton, is used both for cancer research and as a possible skin replacement for burn victims.
- Experts say that only half a dozen types of sharks are very dangerous. Most are shy and harmless, avoiding people and other large animals when possible.
- People kill over a hundred million sharks per year. Shark skins are used to create strong leather. Some sharks are eaten for their meat or in shark fin soup, while others are used for fertilizer.
Summer of the Shark
Time for Kids September 14, 2001 Vol.7 No.1
Photos: National Geographic, SeaPics.com
Summer of the Shark AssessmentName ______
____1. What is the author’s purpose of this article?
- Entertain the reader about the mysteries of sharks.
- Persuade the reader to hunt sharks and kill them for food.
- Provide the reader with general information about sharks
- Persuade the reader to warn others of shark attacks
____ 2. What is the main idea of paragraph 2?
- Chances of being bitten by a shark are very slim.
- Shark attacks are on the rise.
- Sharks are overpopulating the oceans.
- Shark attacks mostly happen in Australia.
____ 3. Which statement from the article is a fact?
A.Most are shy and harmless, avoiding people and other large animals when possible.
B.A great white's bite is so powerful it can exert pressure of 2,000 pounds per square inch.
C.Sharks don't really like to bite people
D.Sharks are one of nature's ultimate designs: confident, sleek and deadly.
_____ 4. That's when most sharks hunt their prey. Using context clues from the article, select a synonym for the word prey.
- Fish
- Food
- Flounder
- Family
____ 5. Sharks have a keen sense of smell. Using context clues from the article, select an antonym for the word keen.
- Great
- Excellent
- Strong
- Poor
____ 6. Which sentence would make a good summary of the article?
- Facts and misconceptions about sharks
- A case of mistaken identity
- Sharks are being killed for no reason.
- Shark attacks are on the rise.
____ 7. Which text feature in the article helps organize facts about sharks?
- Columns
- Bullets
- Photos and captions
- Text boxes
____ 8. In which section of the article would you find out about a shark’s sensitive ears?
- Amazing facts about sharks
- A Case of Mistaken Identity
- A Shark’s Super Senses
- Who’s threatening Whom?
____ 9. In the article, which topic was given first?
A.The author distinguished what types of sharks attack humans.
B.Misconceptions about shark attacks were addressed.
C.Amazing facts about sharks were listed
D.Shark’s super senses were explained.
____ 10. Infer how the author feels about shark attacks.
- The author probably believes shark attacks are a rare occurrence.
- The author probably is afraid to swim in the ocean.
- The author probably thinks sharks are very dangerous creatures.
- The author wants to warn readers of shark infested beaches.
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