Saskia Lacey - Amazing Animals: Sharks: Skip Counting

0covercover.xhtmlcover1page0001page0001.xhtml22page0002page0002.xhtmlAmazing Animals Sharks Skip Counting33page0003page0003.xhtml44page0004page0004.xhtmlTable of Contents Sharks : Friends or Foes? 4 From Teeth to Tail 6 Species of Sharks 12 Save the Sharks! 26 Problem Solving 28 Glossary 30 Index 31 Answer Key 3255page0005page0005.xhtmlSharks : Friends or Foes? When you hear the word shark, what comes to mind? Do you imagine lots of scary, sharp teeth? If you do, you are not alone. Many people are scared of sharks. There are over four hundred different species, or types, of sharks. Not all of them are dangerous. Most sharks do not bother people. When you get to know sharks, one thing is certain : all of them are unique. great white shark66page0006page0006.xhtmlreef shark LET'S EXPLORE MATH Imagine your class visits an aquarium during a school field trip. 1. So far, your friends have counted 37 tanks. They ask you to keep counting at an exhibit with 4 tanks. What are the next four numbers after 37? 2. Aquarium workers are feeding food pellets to fish. As they toss food pellets into the tank, they count back to keep track of how many food pellets are left. Right now, there are 122 food pellets. When counting back from 122, what are the first four numbers they will say?77page0007page0007.xhtmlFrom Teeth to Tail With so many species of sharks, there is a lot of variety in what they look like. But, many sharks share the same anatomy. All sharks are fish. This means that they use gills to breathe and fins to swim. Caudal (KAWD-uhl) fins, or tail fins, give sharks strength. As sharks move from side to side, their fins push them through the water. Parts of a Shark eye gills dorsal fin caudal fin body pectoral Fin mouth88page0008page0008.xhtmlLET'S EXPLORE MATH While at the aquarium, Toby notices that some sharks have 5 gills on each side of their bodies. 1. Skip count by 5s to prove how many total gills one shark has. 2. There are 4 sharks in the tank. Draw a number line similar to the one below. Choose a number to skip count by, and use the number line to prove how many gills four sharks have. 0 5 10 Reef sharks use their strong fins to make quick turns.99page0009page0009.xhtmlMost sharks have pointed fins and snouts. Blue sharks and great white sharks have this shape. It helps them cut through water and swim quickly. Some of these sharks can swim over 40 miles per hour (64 kilometers per hour) when they chase prey. Other species, such as the whale shark and the angel shark, have flat, round snouts. Sharks use this type of snout to bury themselves in the sand. Then, they hide as they wait for prey to swim by.1010page0010page0010.xhtmlwhale shark blue shark1111page0011page0011.xhtmlSharks are known for their grins. Unlike humans, sharks have rows and rows of teeth. When a shark loses a tooth, a tooth from another row moves forward to replace it. Some sharks have very sharp teeth that help them tear apart food. Others have flat teeth that help them crush shells to eat what is inside. Sharks have the teeth they need to hunt prey that live in their habitats. Basking sharks' large mouths and small, pointed teeth help them filter out plankton.1212page0012page0012.xhtmlSand tiger sharks use their sharp teeth to eat small bony fish. LET'S EXPLORE MATH The gift shop at the aquarium sells bags of plastic shark teeth. 1. Each bag holds 10 plastic teeth. Tara buys 8 bags. Use the blanks to skip count by 10s to prove how many total teeth Tara buys. 10, ___, ___, ___, ___, ___, ___, ___ 2. What patterns do you notice when skip counting by 10s?1313page0013page0013.xhtmlSpecies of Sharks All sharks share some traits, such as gills and fins. However, there are other things that make each species unique. Whale Sharks The biggest fish in the world is the whale shark. Whale sharks can be up to 59 feet (18 meters) long. That is longer than a school bus! They hunt by swimming with their mouths open. As they swim, they catch tiny prey and plants. Water flows through their gills while food stays in their mouths. Two scuba divers swim alongside a whale shark.1414page0014page0014.xhtmlThis whale shark gets a mouthful of water and food. LET'S EXPLORE MATH While at the aquarium, the class learns that the 100 peso bill from the Philippines has whale sharks on the back. 1. Students see a display of seven 100 peso bills. Use the blanks to skip count by 100s to prove how many total pesos the money is worth. 100, ___, ___, ___, ___, ___, ___ 2. What patterns do you notice when skip counting by 100s?1515page0015page0015.xhtmlChain Catsharks Whale sharks are named for their size, while chain catsharks are named for their skin. Their name comes from the chain pattern on their brown and yellow skin. Chain catsharks are deep water fish. They hunt squid, fish, and worms. Chain catsharks live on the ocean floor. Their skin helps them blend in with the sand. But catsharks can easily see each other. They see other catsharks as glowing green shapes. Chain catsharks see each other as having bright green skin.1616page0016page0016.xhtmlHumans see chain catsharks as having brown-and-yellow skin.1717page0017page0017.xhtmlAngel Sharks Like catsharks, angel sharks live on the sea floor. When angel sharks hunt, they first hide in the sand. They wiggle back and forth until their bodies are covered. Only their eyes can be seen. Then, they wait for prey to pass. Angel sharks can lay still on the sea floor for over a week! When angel sharks see prey, they pop out of the sand and snap their jaws shut. angel shark1818page0018page0018.xhtmlA scuba diver swims by a covered angel shark.1919page0019page0019.xhtmlGoblin Sharks Goblin sharks also live on the sea floor. These pink sharks are known for their unique jaws. When they hunt, they can stretch their jaws out of their mouths by up to 3 inches (8 centimeters)! They can do this because their jaws are not attached to their mouths. Instead, they are connected to flaps of skin. The skin unfolds to let the shark catch prey. This trait lets them catch prey from farther away.2020page0020page0020.xhtmlThis diagram shows how a goblin shark stretches its jaw out of its mouth to catch prey.2121page0021page0021.xhtmlNurse Sharks In warm, shallow waters, people may spot nurse sharks. Their brown color helps them to blend in with the sand. These sharks move slowly and eat small creatures. The strong jaws and size of nurse sharks scare some people. After all, they can be up to 14 ft. (4 m) long! But nurse sharks are gentle. They will not attack humans unless they feel they are in danger. A diver swims by a nurse shark.2222page0022page0022.xhtmlThe two pointed objects near nurse sharks' mouths are actually part of their noses.2323page0023page0023.xhtmlHammerhead Sharks Hammerhead sharks stay near the water's surface. These sharks are easy to spot by their unique heads. Their huge size makes them stand out, too. Some can weigh up to 1, 000 pounds (450 kilograms)! As they swim, these sharks swing their heads from side to side. This lets them use their wide-set eyes to see all around. They can see both in front of and behind themselves as they swim. This trait helps hammerhead sharks hunt and stay safe. hammerhead shark2424page0024page0024.xhtml2525page0025page0025.xhtmlGreat White Sharks Great white sharks are one of the most well-known species of shark. Their huge jaws have up to three hundred big, sharp teeth that can chomp through most things. Great white sharks are at the top of the ocean food chain. They eat everything from sea turtles to small whales. These sharks follow the smell of blood. Great white sharks can smell blood of prey from up to 3 mi. (5 km) away!2626page0026page0026.xhtmlGreat white sharks' teeth have tiny, saw-like edges. A great white shark jumps out of the water to catch a seal.2727page0027page0027.xhtmlSave the Sharks! Humans hunt sharks for food and sport. This is not good for sea life. Sharks help keep the food chain in balance. People need to work together to keep sharks safe. Keeping the oceans clean can keep sharks safe. Not buying products with shark in them, such as food and clothing made from sharks' meat and skin, can help, too. Sharks come in all shapes and sizes. Some sharks are dangerous and some are harmless. But each is a unique creature that needs to be protected.2828page0028page0028.xhtml2929page0029page0029.xhtmlProblem Solving Tiger sharks can swim up to 20 miles per hour. With that quick speed, they can travel long distances in short amounts of time. Imagine that scientists track some tiger sharks with electronic tags. Using data from the tags, they find out how far the sharks swim each month. The table shows how far four tiger sharks swam from January to June. Use skip counting to find the pattern for each shark's swimming habits, and complete the table. Then, describe each shark's swimming pattern.