Flip open the pages of this mini-book to shed light on the layers of the ocean. Habitat Hallmarks T he ocean covers about 71 percent of the earth. The shallow part of the ocean lies above the continental shelf, which extends from the shoreline to the edge of each continent. Beyond that, the ocean can be more than six miles deep. Sunlight reaches to about 492 feet (150 m) beneath the water s surface. Within this sunlit zone live one-celled algae that make up the plant plankton. Like plants, algae make food using energy from the sun. One-celled animals, copepods, shrimp-like krill, and baby fish make up the animal plankton, which feed on algae. Plankton serves as food for small fish, basking sharks, and toothless whales. Killer whales, meat-eating sharks, and other large fish swim in to feast on the millions of small fish attracted to plankton-rich waters. Beneath the sunlit zone is the twilight zone, where light is very dim. During the day, shrimps, small fish, and even some animal plankton might dive there to hide from predators. As darkness falls, these hiders rise to feed. Somewhere in the twilight zone a sperm whale might hunt for a giant squid to eat. Below the twilight zone are the cold waters of the zone of darkness. There, the only light comes from special body parts on some fish. By flashing light, these fish can attract a mate or a meal, or scare away a predator. Very few animals live in the near total darkness, and no plants grow there. Food particles that sink from the upper zones provide food for these deep-sea dwellers. Still farther down, chemicals seep out of openings in parts of the deep-sea floor. Bacteria use these chemicals to make food. The bacteria live inside some deep-sea creatures, such as tube worms, and share food with them. Materials Making the Mini-book 1 Photocopy pages 47 49. Cut out all the pieces along the thick, solid outer lines. 2 Fold down the ocean piece along the dashed line, as shown. Fold down the blank part of the zone of darkness piece along the dashed line. Reproducible pages 47 49 Scissors Tape Blue construction paper or white paper to be colored Crayons, colored pencils, or markers (optional) 45
O c e a n More to Do Deep Sea Dive The Mariana Trench in the Pacific Ocean is the deepest part of the sea. Challenge students to find out about the trench: where it is, how people reach it, and what lives there. Encourage students to draw maps and pictures about this mysterious part of the planet. Resources I Wonder Why the Sea Is Salty and Other Questions About the Oceans by Anita Ganeri (Kingfisher, 2003). There s more to learn about the ocean than the animals that live in it. This book answers basic questions most students have about the ocean. http://www.cybrary.org/ ocean.htm There s an oceanful of information on this site, ranging from sea life to waves and tides to the sea floor to the deep ocean trenches. 3 Lift the ocean flap and tape the sunlit zone on the underside. 4 Insert the folded zone of darkness piece into the ocean piece. Matching up their folds, tape the two pieces together, as shown. 5 On the blank page under the sunlit zone, tape the twilight zone text box and the animal piece for page 2, as shown. 6 Lift page 3. Tape the deep sea floor text box on the blank page. Tape the animal piece for page 4 at the bottom of the page, as shown. 7 Tape the cutout piece with five fish above the whale on page 2. Tape the jellyfish to the left of the sunlit zone, as shown. 8 Tape the nautilus with its tentacles sticking out anywhere on page 3. 9 Tape the remaining pieces around the ocean at the top of the book. Teaching With the Mini-book Invite students to color, assemble, and read the text on their mini-books. Then check for understanding by asking them these questions: 1 What are the four zones in the ocean where creatures live? (Sunlit zone, twilight zone, zone of darkness, deep-sea floor) 2 What makes up plankton? What eats it? (Algae that make food and one-celled animals make up plankton. It is food for small fish and some sharks and whales.) 3 Describe the twilight zone. (This part of the ocean is dim because little sunlight reaches the twilight zone. Some fish hide there. Whales hunt squids to eat.) 4 Where does light come from in the zone of darkness? (Certain fish give off light to attract animals to eat.) 46
5 tk Ocean Swordfish Tiger shark Sperm whale The Ocean 1 Giant squid 2 Very little sunlight reaches down to the twilight zone. Some small fish dive here to hide during the day. In the cover of night, they swim up to eat plankton. In these depths, a hungry sperm whale might battle with a giant squid in order to eat. TWILIGHT ZONE 47
Tube worms Tripod fish 48 4 The deep-sea floor is miles below the surface of the water. Bits of food slowly sink from above. A tripod fish inches along on its three very long fins. Giant tube worms sway back and forth. Every year, new kinds of life are found at the bottom of the ocean. Sea pen DEEP-SEA FLOOR ZONE OF DARKNESS No sunlight ever reaches the zone of darkness. But flashes of light might blink from fish, such as anglerfish and eels. These fish give off light to attract animals into their large, open jaws. The water temperature stays very cold this far down in the ocean. Lanternfish Anglerfish Snipe eel Stomach eel 3
SUNLIT ZONE In sunlit parts of the ocean, tiny algae use the sun s energy to make food. Algae, along with equally tiny animals, make up plankton. Plankton serves as food for small fish. In turn, bigger fish prey on the small fish. The sunlit zone teems with life. Jellyfish Nautilus Mackerels Sea turtle Gull Plankton Dolphin Plankton 49