Original broadcast: January 20, 2004 BEFORE WatCHIng Secrets of the Crocodile Caves 1 Ask students to find Madagascar on a world map. How might the fact that Madagascar is an island PRogRAM OVERVIEW affect its biodiversity? What kinds of animals might live there? NOVA profiles the lives of two of 2 Discuss with students the concept Madagascar’s many species—the crowned of an energy pyramid. Be sure to lemur and the cave-dwelling crocodile. emphasize the direction of energy transfer in the pyramid from prey The program: to predator. • explores Ankarana, a reserve in 3 As students watch, have them take northern Madagascar, which is home notes on predator and prey relation- to a region of stone forests and unique ships on Madagascar. Organize animals and plants. the class into three groups to • documents the crowned lemur’s way of life, focusing on a troop take notes on 1) land animals and plants, 2) animals that live in the of lemurs led by a one-eyed queen. water, and 3) animals that primarily • discusses the evolutionary history of crocodiles and lemurs. live in the sky. Have students create • explores the relationship between cave-dwelling crocodiles and a a chart with columns labeled local tribe that believes they are sacred and protects them. “animal name,” “eats,” and “is eaten by.” Students can use their • features the fossa, a lemur-hunting carnivore that lives nowhere notes to complete the “Home else on Earth. Sweet Home” activity on page 2. • uses special filming techniques to capture the lepilemur, aye-aye, and other nocturnal animals. • presents the lifestyle of the crocodiles, which retreat to caves to AFTER WatCHIng cool their ectothermic bodies. • showcases how lemurs, crocodiles, and other animals and plants 1 Ask students to describe the role played (niche occupied) by the on Madagascar have developed adaptations suited to their own lemur in its community, or that well-defined niches. played by the crocodile. How are these roles alike? How are they Taping Rights: Can be used up to one year after the program is taped off the air. different? What might happen if the lemurs moved into the caves and the crocodiles moved into the forest? 1 NOVA TEACHER’S GUIDE www.pbs.org/nova/croccaves/ CLASSRooM ACTIVITY StanDARDS ConnECTIon Objective To learn about a small segment of the complex food web of a region The “Home Sweet Home” activity aligns with the following National in Madagascar. Science Education Standards. Materials for each team GRades 5–8 • copies of the “Home Sweet Home” student handout Science Standard C: • several sheets of unlined paper Life Science Populations and ecosystems • ruler • The number of organisms an ecosystem can support depends Procedure on the resources available and 1 Organize students into groups of three so that one member of each abiotic factors, such as quantity of light and water, range of group has notes on the different categories outlined in the Before temperatures, and soil composition. Watching activity #3 on page 1. Provide copies of the student handout Given adequate biotic and abiotic and other materials to each group. resources and no disease or 2 Discuss with students the concept of a food web. They are probably predators, populations (including humans) increase at rapid rates. familiar with a simple food chain (e.g., grain is eaten by mice that Lack of resources and other factors, are eaten by an owl). A food web is a more complex model of feeding such as predation and climate, relationships that includes many interconnected food chains. limit the growth of populations in 3 After watching, have students in each group identify all the plants specific niches in the ecosystem. and animals on the student handout and draw arrows from each plant GRades 9–12 or animal to the animal that eats it. Then, using their program notes and Science Standard C: student handout, have students draw a food web for the plants and Life Science animals of northern Madagascar. Note to students that these plants The Interdependence of Organisms • Energy flows through ecosystems in and animals are only a small part of the food web in this region of one direction, from photosynthetic Madagascar. Ask students to draw arrows from an animal or plant to the organisms to herbivores to carni- animal that eats it to illustrate how energy flows through the food web. vores and decomposers. 4 Ask students to choose one food chain from their food web and use it • Living organisms have the capacity to produce populations of infinite size, to draw an energy pyramid. An energy pyramid shows how energy flows but environments and resources are through the food chain. finite. This fundamental tension has 5 To conclude, hold a class discussion about the balance of the food web. profound effects on the interactions What might happen if one organism were taken out of the web? What between organisms. if an organism, such as another species of lemur, were added? 6 As an extension, have students investigate what other plants and animals live on Madagascar and brainstorm how those plants and Video is required animals might fit into the food web students created. for this activity. Classroom Activity Author Dwight Sieggreen has been teaching middle school science for 35 years in Northville, Michigan. He currently serves as president of the National Association of Presidential Awardees for Excellence in Science Teaching. SECRETS OF THE CROCODILE CAVES 2 NOVA TEACHER’S GUIDE 2 www.pbs.org/nova/croccaves/ ACTIVITY ANSWER LINKS & booKS As you review completed food webs If the fig trees were struck by dis- Links with students, remind them that the ease, the population of crowned NOVA Web Site—Secrets of the animals and plants they used for lemurs might decrease. Predator Crocodile Caves their food web are just a small populations might also decrease. www.pbs.org/nova/croccaves/ In this companion Web site for the segment of the living organisms on Since figs are not only a staple for NOVA program, view panoramas of Madagascar. The real food web is crowned lemurs, but also for their Ankarana, learn about the legends of far more complex. The web below competitors, the populations of Madagascar, find a who's who of croc- shows some of the interactions many species dependent on figs odile species, and explore the anatomy among plants and animals. would decrease. Their predators of a crocodile. Some of the foods crowned lemurs would grow hungry and possibly Madagascar: Biodiversity starve. and Conservation eat are figs, flowers, and leaves. ridgwaydb.mobot.org/mobot/ (They also eat tamarind pods, tree The animals that crocodiles eat that madagascar/ fruits, cicadas, screw plants, and are shown on this program include Highlights the biodiversity of other items not shown in this film.) crowned lemurs, domesticated Madagascar, including a section on the dry tropical forest. Two of the crowned lemur’s zebu, and blind fish and shrimp. predators are crocodiles and fossas. The population of crocodiles is Sights & Sounds—Madagascar The crowned lemur’s competitors Dry Forests affected by the availability of www.nationalgeographic.com/ include Sandford’s lemurs and their prey. wildworld/madagascar/ ring-tailed mongooses. Shows photos and video clips of some of Madagascar’s rare animals, such as fossas and crowned lemurs. Books Garbut, Nick. SaMPLE FooD WEB Mammals of Madagascar. New Haven: Yale University Press, cave 1999. fossa crocodile Provides an overview of Madagascar’s diverse group of 117 mammal species, more than 100 of which are endemic to the island. domesticated blind fish Tyson, Peter. zebu and shrimp The Eighth Continent: Life, Death, and Discovery in the Lost crowned World of Madagascar. lemur New York: William Morrow, 2000. Describes Madagascar through the Sanford’s ring-taled fruit bat eyes of four scientific experts—a aye-aye lemur mongoose (droppings) herpetologist, a paleoecologist, an archeologist, and a primatologist— as they explore the world’s fourth-larg- est island. grub fruits, cave maggot flowers, cricket leaves Major funding for NOVA is provided by Google and BP. Additional funding is provided by the Howard Hughes Medical Institute, the Corporation for Public © 2004 WGBH Educational Permission Foundation. granted for educational use only. Broadcasting, and public television viewers. SECRETS OF THE CROCODILE CAVES 3 NOVA TEACHER’S GUIDE 3 www.pbs.org/nova/croccaves/ Secrets of the Crocodile Caves Student Handout Home Sweet Home Madagascar is home to a wide 3 Choose a food chain from within 2 If the fig trees were struck variety of organisms that occupy your food web and draw an by disease, how would the specific niches. Each species energy pyramid with the parts of population of crowned lemurs is connected to other species that food chain. To create your be affected? How would the through a food web and depends energy pyramid, draw a triangle crowned lemurs’ predators on other species for survival. Learn and divide it into a top, middle, be affected? How would this about some of those relationships and bottom. Show how energy affect the entire food web? in this activity. flows through the food chain by 3 Circle the crocodile. What does writing the plant in the bottom the crocodile eat? The adult Procedure segment, the animal that eats crocodile in the Ankarana region 1 Take careful notes of all the the plant in the middle, and the of Madagascar is free from animals as you watch NOVA’s animal that eats that animal at predators because the Ankarana “Secrets of the Crocodile Caves.” the top. tribe holds the crocodile sacred. Then label all the plants and What other factors affect the animals in this illustration. Draw Questions population of crocodiles? What arrows from each plant or animal Write your answers on a separate dangers threaten the eggs and to the animal that eats it.