Native vs. Non-native Species: Who Will Win? Session 1
Conduct this session in the classroom.
- Place a kilogram (equal to about two pounds) of gram stackers on each corner of the cookie sheet. Stack the masses so they are as close to the corners as possible. Stand the flashlight on end in the middle of a table, and carefully balance the cookie sheet on top of the flashlight. Explain to students that each corner represents one of four types of organisms in the habitat of our geographic region: carnivores, herbivores, plants, and decomposers. The carnivores eat a certain number of the herbivores, who eat a certain amount of the plants; in turn, when the animals die, they provide a certain amount of food for the decomposers, who make a certain amount of nutrients available to the plants. This energy cycle keeps the populations of all the different species in balance.
- Suggest that a new animal has been brought here from another habitat. It eats the plants in the ecosystem, and, because the new animal has no natural predators here, its numbers increase and it significantly diminishes the plant life. While describing this drama, remove masses one-by-one from the plant corner of the cookie sheet until the sheet topples.
- Explain that the four groups of organisms represented on the cookie sheet at the beginning of the demonstration are native to the region and that the newcomer is called a non-native species. Explain the concepts of native and non-native species as described in the lesson plan Background. Tell them that certain non-native species are invasive and have caused problems in water environments like the Chesapeake Bay and in other environments in Virginia and the United States.
- Assign the following non-native species for students to research:
- anthracnose fungus (anthracnose)
- Asian longhorned beetle (Anoplophora glabripennis)
- Asiatic clam (Corbicula fluminea)
- Chestnut blight (Cryphonectria parasitica)
- comb jelly (Mnemiopsis leidyi)
- Eurasian water milfoil (Myriophyllum spicatum)
- grass carp (Ctenopharyngodon idella)
- green crab (Carcinas maenas)
- gypsy moth (Lymantria dispar)
- hydrilla (Hydrilla verticillata)
- kudzu (Pueraria montana var. lobata)
- mute swan (Cygnus olar)
- nutria (Myocastor coypus)
- phragmites (Phragmites australis)
- purple loosestrife (Lythrum salicaria)
- starlings (Sturnus vulgaris)
- veined rapa whelk (Rapana venosa)
- yellow iris (Iris pseudacorus)
- zebra mussel (Dreissena polymorpha).
Depending upon student reading level, you may assign all the organisms, giving one to each student, or you may choose to assign only some and have students research in pairs. If you do not assign all, be sure to include some land dwellers and some water dwellers, as well as some plants, some animals, and at least one fungus. Use the reference materials listed in the Materials section, as well as non-fiction books and encyclopedias (also see Resources). The "Exotics in the Chesapeake" fact sheets (see Resources) contain specific information, and you might cut them apart to give to the students researching those organisms.
Direct students to conduct research on their assigned species and to take notes on the organism's characteristics such as
- appearance, including as many details as possible
- native habitat
- problems resulting from its invasion
- region where problems have occurred.