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Contributor: Suzanne Riordan. Lesson ID: 13949
Just what does a sawfish do with its saw? How does an octopus change color and shape? And what in the world is a sea dragon? Meet some strange sea creatures and learn how to analyze text structure!
Watch the news story below about a man who did just that!
The sea is full of fascinating creatures! In this lesson, you'll read about several of them.
You caught a glimpse of a sawfish in the above video. Read the following article to learn more.
While reading, consider how the writer uses text structures such as the following.
What Does a Sawfish Do With Its Saw?
Sawfish are easy to recognize because of their long snouts lined with sharp teeth. Many people think these snouts, called rostrums, look like saws. In the shallow coastal waters of the Gulf of Mexico and freshwater rivers in the southern United States, two types of sawfish are found: the smalltooth sawfish (Pristis pectinata) and the large-tooth sawfish (Pristis Peretti). Both are closely related to sharks. Five other species live in different oceans around the world. Sawfish can grow quite large. Smalltooth sawfish usually reach about 18 feet (5.5 meters) long, but some can grow up to 25 feet (7.5 meters). Unfortunately, the smalltooth sawfish are endangered because of habitat loss, overfishing, and getting caught in fishing nets.
Some people might worry that sawfish are dangerous to humans, but sawfish don't attack people and usually avoid swimming areas like beaches. So, what do they use their saws for? They aren't cutting down trees underwater! Sawfish use their saws to hunt for fish and crustaceans.
Scientists used to think sawfish used their saws mainly to dig through the sea floor for food. However, recent research shows that the sawfish's rostrum is more than a digging tool. It has thousands of tiny sensors (ampullary pores) that can detect the electric fields around living creatures. These sensors help sawfish find fish swimming nearby. Once they find their prey, they use quick back-and-forth swipes of their saw to catch and kill their food, making it easier to eat!
Analyze how this piece is written. Part of the text is a description, and part is a problem and solution. Both of these structures help communicate the idea that sawfish are amazing creatures.
The writer describes sawfish in the first paragraph. In your notebook, create a chart like the one below. Then, look back and find some descriptive words to complete it.
| Describes Its Body |
|
|
| Describes Its Habitat |
|
|
| Describes The Species |
|
|
| Describes Its Size |
|
|
| Describes Its Status |
|
In the remaining paragraphs, the writer poses problems and solutions. Look in the text to find the solutions to these problems.
| Problem | Solution | |
| People fear sawfish may be dangerous to humans. |
|
|
| It wasn't fully known what sawfish used their saws for. |
|
When you read an informational passage, it's essential to understand the main idea of each paragraph.
The main idea is often stated in the first sentence, but not always. Ask yourself what all the paragraph details add up to.
Look at each paragraph again.
Paragraph One
Sawfish are easy to recognize because of their long snouts lined with sharp teeth. Many people think these snouts, called rostrums, look like saws. In the shallow coastal waters of the Gulf of Mexico and freshwater rivers in the southern United States, two types of sawfish are found: the smalltooth sawfish (Pristis pectinata) and the large-tooth sawfish (Pristis Peretti). Both are closely related to sharks. Five other species live in different oceans around the world. Sawfish can grow quite large. Smalltooth sawfish usually reach about 18 feet (5.5 meters) long, but some can grow up to 25 feet (7.5 meters). Unfortunately, the smalltooth sawfish are endangered because of habitat loss, overfishing, and getting caught in fishing nets.
Paragraph Two
Some people might worry that sawfish are dangerous to humans, but sawfish don't attack people and usually avoid swimming areas like beaches. So, what do they use their saws for? They aren't cutting down trees underwater! Sawfish use their saws to hunt for fish and crustaceans.
Paragraph Three
Scientists used to think sawfish used their saws mainly to dig through the sea floor for food. However, recent research shows that the sawfish's rostrum is more than a digging tool. It has thousands of tiny sensors (ampullary pores) that can detect the electric fields around living creatures. These sensors help sawfish find fish swimming nearby. Once they find their prey, they use quick back-and-forth swipes of their saw to catch and kill their food, making it easier to eat!
Good job identifying text structures and main ideas!
Move to the Got It? section now!
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