LIZARDSLIZARDS && SNAKES:SNAKES: ALIVE!ALIVE! EDUCATOR’SEDUCATOR’S GUIDEGUIDE www.amnh.org/lizardswww.amnh.org/lizards Inside: • Suggestions to Help You Come Prepared • Must-Read Key Concepts and Background Information • Strategies for Teaching in the Exhibition • Activities to Extend Learning Back in the Classroom • Map of the Exhibition to Guide Your Visit • Correlations to National and NYC Standards • Connections to Other Museum Halls for Further Investigation KEYKEY CONCEPTSCONCEPTS Squamates—legged and legless lizards, including snakes—are among the most successful vertebrates on Earth. Found everywhere but the coldest and highest places on the planet, 8,000 species make squamates more diverse than mammals. Remarkable adaptations in behavior, shape, movement, and feeding contribute to the success of this huge and ancient group. BEHAVIOR Over 45O species of snakes (yet only two species of lizards) An animal’s ability to sense and respond to its environ- are considered to be dangerously venomous. Snake venom ment is crucial for survival. Some squamates, like iguanas, is a poisonous “soup” of enzymes with harmful effects— rely heavily on vision to locate food, and use their pliable including nervous system failure and tissue damage—that tongues to grab it. Other squamates, like snakes, evolved subdue prey. The venom also begins to break down the prey effective chemoreception and use their smooth hard from the inside before the snake starts to eat it. Venom is tongues to transfer molecular clues from the environment delivered through a wide array of teeth. For example, to sensory organs in the roof of their mouths. This allows vipers employ hypodermic needle-style fangs that fold them to detect and track prey (even in complete darkness), inside the mouth when not in use. which they then seize with their teeth. HABITATS, ECOSYSTEMS & ENERGY Squamates, like all other animals, communicate with Adaptations in form enable animals to live in a variety of members of their own species and other organisms. environments. Squamate habitats range from deserts to Except for the distinctive vocalizations of geckos, most rain forests, treetops to underground burrows, and coral squamates are silent, yet they get their message across. reefs to the open ocean. For example, like walking billboards, chameleons change the color patterns along their fl anks to talk to each other. Most squamates are ectothermic: they use external heat There are as many “languages” as there are species! sources to maintain a relatively constant body temperature. Because this conserves energy, some squamates can go Whether being hunted as prey or threatened for territory, for long periods (more than a year in some cases) between animals have ways to protect themselves. Squamates may feedings. For snakes, that typically means eating something react to danger by biting, fl eeing, infl ating their bodies, or really big. And they do this with no hands! Flexible skulls, gaping (exposing colored tongues and throats). Some play elastic jaw ligaments, and remarkable digestive function dead, squirt blood from their eyes, or use venom to keep make this possible. danger at a distance. In extreme danger, some squamates may sacrifi ce parts of their bodies—a tail, or even large pieces of skin—to distract and escape from predators. EVOLUTION Over the course of biological evolution, species adapt and STRUCTURE & FUNCTION change over time. All organisms differ among themselves (variation) and pass traits on to their offspring (inheritance). Species within a group can have diverse forms and sizes. Over many generations, those better-adapted organisms Squamates range in size from the Dwarf Gecko, which can may give rise to new species (selection). stand on a dime, to the extinct Mosasaurus, which grew to 17 meters (56 feet) long. Some squamates have four limbs All of the almost 8,000 living squamates can trace their while many have no limbs at all; some have only back legs, lineage back to one common ancestor that lived at least others only front legs; and many intermediate conditions 200 million years ago. Since that time, many squamate exist. These diverse body plans enable them to move on groups have gone extinct and new groups have evolved. the ground, in water, and even in the air. For example, Dozens of squamate groups have undergone limb reduc- geckos have toe pads with nano-hairs that allow them to tion and loss. Limblessness is an excellent adaptation to cling to and move across many surfaces; sea snakes rely on life underground, where much food is found and predators paddle-like tails to traverse oceans; and some squamates are few. Losing limbs may have allowed squamates to take have wing-like structures that enable them to glide. advantage of resources unavailable to limbed vertebrates. Crypsis is a phenomenon in which an organism’s appear- Scientists discover new squamate species all the time, and ance allows it to blend well into its environment. Chame- the more we learn, the more new questions about squa- leons, for example, employ crypsis when they rock like a mate diversity arise. For example, how many lineages of shaking leaf to blend in with vegetation. Some squamates squamates have lost limbs? How many times has venom are mimics, like the harmless Campbell’s Milk Snake, which evolved? How can answers to questions like these help us resembles a highly venomous Coral Snake. Many brown protect these amazing animals? and gray forest-dwellers are well camoufl aged when they sit motionless on the trunks and limbs of trees. What’s a Squamate? Come Prepared What do iguanas, chameleons, monitor lizards, geckos, vipers, Review this guide and additional online resources and cobras have in common? They’re all squamates (skwah- to help plan your visit ahead of time. Give students mates). Squamata, which means “scaly” in Latin, is the name directions and supplies before you arrive, since it can scientists use for the group that includes legged and legless be hard to do so once at the Museum. lizards, including snakes. The exhibition and the activities in this guide are Squamates are vertebrates, animals with a backbone. Unlike correlated to the National Science Education mammals and birds, which generate their own body heat, most Standards listed below. On our website you’ll fi nd squamates are ectothermic—they use external heat sources to correlations to the New York City Performance maintain a relatively constant body temperature. All squamates Standards and the NYC DoE Draft Middle School have scales (though other kinds of animals do too) and they Scope and Sequence. periodically shed their skin. Every squamate—each male and female—has paired, or two of the same, reproductive organs. All online resources, including a glossary, reference lists, and standards, are available at www.amnh.org/ Fossil evidence shows that squamates existed at least 200 million years ago, when dinosaurs began to fl ourish. These early resources/lizards. Information about school visits is lizards were probably small, diurnal, ground-dwelling predators available at www.amnh.org/education/schools. with spiky ridges down their backs. Over time, as squamates Grades K–4 adapted to live in many different environments, they evolved Standard A: Science as Inquiry extremely diverse characteristics. For example: • Abilities necessary to do scientifi c inquiry • Understandings about scientifi c inquiry G R Standard C: Life Science E E • Characteristics of organisms N B Some squamates fl y, some parachute, some A S I • Life cycles of organisms L I S walk upside down on ceilings, and K some, like Green Basilisk Lizards, • Organisms and environments L I Z A R can even sprint across water. 5–8 D Grades Standard A: Science as Inquiry • Abilities necessary to do scientifi c inquiry • Understandings about scientifi c inquiry Standard C: Life Science • Structure and function Some squamates, like • Reproduction and heredity Veiled Chameleons, have • Regulation and behavior lightning-fast tongues that • Populations and ecosystems • Diversity and adaptations of organisms can be fi red with pinpoint V Standard F: Science in Personal and Social Perspectives E I L E D accuracy to grab prey. C H A M E L E O N • Populations, resources, and environments Grades 9–12 D S P I T Standard A: Science as Inquiry R E T I N • Abilities necessary to do scientifi c inquiry G CO Some squamates have highly B R A • Understandings about scientifi c inquiry toxic venom that can subdue Standard C: Life Science prey in seconds, and some, like • Biological evolution Red Spitting Cobras, can spray • Interdependence of organisms venom into a predator’s eyes. • Matter, energy, and organization in living systems • Behavior of organisms S E P Y THON M E B U R Prior to your visit, you can download and Some squamates may eat distribute copies of Be an Exhibition Explorer several times a day, while and a Family Guide. Students can use the Be an others, like Burmese Pythons, Exhibition Explorer fi eld journals to record their can get by with one large meal observations and research. The Family Guide a year—when they can swallow provides a kid-friendly guided tour through the whole an animal as large as a deer! exhibition. TEACHINGTTEACHINGEACHING INIINN THETTHEHE EXHIBITIONEEXHIBITIONXHIBITION Explore the Key Concepts with these possible paths through the exhibition. Use the map to locate the animals and plac- es indicated in italics. You may wish to divide your class into small teams. Each team can investigate one question and record its fi ndings to share back in the classroom. Note that animals in captivity do not always behave like ones in the wild, so students won’t be able to see all of their characteristic behaviors. This makes the supporting exhibition text and images a great resource. BEHAVIOR C H U C K WA L L A How Do Squamates Sense Their Environment? Ask students to observe four animals: Collared Lizard, Eastern Water Dragon, Green Tree Monitor, and Eastern Green Mamba.