Mammals Middle School

Nature Net’s Pre- and Post-Field Trip Materials

Subject: Mammals

Level: Middle School

Introduction

North America is rich with different mammals living in many different habitats: forests, swamps, prairies, farms, deserts, oceans and mountains. Mammals are unique in a few ways. They have hair, they have a backbone, they are warm-blooded, and they have a four-chambered heart. With the exception of three very unusual species, mammals give birth to fully-developed, live babies, and mothers have mammary glands to produce milk for their young (hence the Order "Mammalia").

Vocabulary

Vertebrate - a animal that has a backbone and a central nerve cord that runs through it. Vertebrates are a large group of animals that include sharks and fish, amphibians, reptiles, birds and mammals.

Fur - a covering of hair on the skin that is unique to mammals. Hair serves to protect the skin and keep the body warm. Compare the hair of mammals with the feathers of birds and the scales of reptiles and fish. All mammals have hair on their bodies at some point in their lives.

Circulation and breathing - a very powerful 4-chambered heart allows mammals to pump blood quickly and efficiently. (The only other group of animals that have a 4-chambered heart is the class Aves, birds. Others have 3 or fewer chambers.) Therefore, mammals’ blood carries more oxygen than any other type of animal. In addition, only mammals have a diaphragm, a muscle that allows the chest and lungs to expand greatly and take in lots of air to obtain oxygen. Oxygen fuels metabolism, an energy-making process. These characteristics allow mammals to be more active than reptiles, fish and amphibians.

Endothermy and ectothermy - Mammals are endothermic, or "warm-blooded." They can maintain a constant body temperature over time through internal regulation. The fur of mammals helps them in this task by serving as insulation (as do the feathers of birds!) Reptiles, amphibians and fish are ectothermic or "cold-blooded," meaning they cannot internally regulate and maintain a constant body temperature. Their body temperature changes with that of the surrounding climate. Endothermic animals eat much more, and are able to be more active than exothermic animals.

Habitat - an ecological concept that refers to the type of place where an organism is commonly found. The place is described by topography, geography, climate and other species present. Some mammals are generalists and found in a wide range of habitats; others are specialists and can live in only a very narrow range of habitats. For instance the raccoon is a generalist that thrives in wooded areas, farms, and urban areas whereas the marten is found only in old growth forests.

Hibernation - some mammals, like the woodchuck, enter into hibernation when it gets cold. Hibernation is a time when a mammal lowers its rate of metabolism and lives in a state of stillness, like a long "sleep." Rather than going south, like many birds do, they find a safe, warm place to hole up and spend the winter months. Hibernation takes much preparation, and a lot of time is spent eating so that the mammal will have enough food stores to last most of the winter.

Wildlife Management - the science and practice of conserving and protecting wildlife and their habitat. Wildlife managers conduct scientific research to understand different animals and how to protect them. They make plans to ensure that animals are available for human consumption and recreation, as well as to ensure that animals do not go extinct. They employ many techniques, such as stocking, artificial breeding, habitat and ecosystem protection, to achieve these goals. The work of wildlife management is done by federal and state agencies (U.S. Fish and Wildlife Service, EPA, state Departments of Natural Resources) and nonprofit organizations (e.g. Audobon Society, The Nature Conservancy).

Concepts and Issues

Classification (or Taxonomy): scientists divide all animals into categories or groups, based on certain features they have in common. This process is called "classification." All animals belong to the kingdom "Animalia." Mammals belong to the phylum "Chordata," because they have a spinal cord; the subphylum "Vertebrata" because they have a backbone; and the class "Mammalia" because they have all the characteristics listed above. ["King Phillip Called Out For Green Spaghetti"… Kingdom, Phylum, Class, Order, Family, Genus, Species] A rule of thumb is that organisms grouped at one level share more characteristics than those at the next level above. Mammals are often placed into categories based on the type of food they eat, and the number and type of teeth they have.

Orders of Mammals in Wisconsin: Marsupialia (Marsupials: opossums); Insectivora (Insectivores: shrews and moles); Chiroptera (bats); Lagomorpha (hares and rabbits); Rodentia (Rodents: a large group including squirrels, mice and voles, beavers and porcupines); Carnivora (Carnivorous mammals: dogs, wolves, bears, raccoons, weasels, cats); Artiodactyla (Hoofed mammals: deer, elk, moose and bison).

Evolution: classification would be a meaningless and arbitrary task if it weren’t for the body of theory called evolution. Evolution makes classification make sense! It is a true cornerstone of biology and environmental thinking in the Western world. Basically, evolution rests on these ideas: 1) living organisms today are the modified descendants of organisms from the distant past; 2) throughout life every organism is constantly responding to its environment; and 3) flexibility in the genetic makeup of organisms allows them to change over time so that they do better (adaptation), or worse in their environment. The process results in divergence among populations, the appearance of new species and the disappearance of others.

Ideas for Post-Visit Activities

Discuss relationships among animals - e.g. predator-prey - and adaptations that help predators in the hunt and prey in the escape. Discuss food chains, and play the food web game outlined in Hands-On Environmental Science Activities by Eugene Kutscher.
Read about and discuss cultural perceptions of misunderstood mammals such as wolves or bats. Talk with students about the role of values and attitudes in these perceptions.
Discuss the history of wildlife management and ecology by reading from Aldo Leopold’s A Sand County Almanac.
Discuss wildlife management as a potential career and profession. (You can use Leopold as an example!)
Talk about the diversity of mammals in Wisconsin (and all over the world) with slides. Discuss the endangered mammals in the state (Timber Wolf and Pine Marten), and processes that have made them so.

Reference and reading

Project Learning Tree EE Activity Guide. American Forest Foundation, Washington, D.C. 1994.

Stellaluna. Janell Cannon, Harcourt Brace, 1993.

Peterson’s First Guide to the Mammals. P. Alden and R. Grossenheider, Houghton Mifflin, 1976.

Hands-On Environmental Science Activities (Teachers’ Edition). Eugene Kutscher, Alpha Publishing Co., Annapolis, 1991.

*Check this web site for helpful WI endangered species info: http://dnr.wi.gov/org/land/er/wlist/statelisted.asp