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Activity Guide

Study Science

Season 2 Materials

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Activity Guide
Invaders: Drawing Conclusions


  • Create an online gallery of student cartoons.
  • Convert cartoon characters to puppets (species illustrations enlarged and mounted on paint sticks) to save on drawing time and make the activity more relevant in an auditorium setting.
  • Use butcher paper rolls to create giant comic strips that can be displayed on gallery walls.


Create a comic strip that depicts an alien species arriving in a new habitat. Then draw a conclusion (literally!) of what impacts this alien might have had.


Students will:

  • Name some ways that introduced species behave in a new environment.
  • Describe some characteristics of an alien species that are likely to cause problems in its new environment.
  • Explain why scientists cannot always predict how an alien species will affect its environment.


Art, Science


ballast water, ginkgo, London plane tree, wetland


3 sessions


Copies of handouts: Aliens From the Deep and Alien Impacts, Paper and drawing materials for making comic strips

Educator Page: Answers to Alien Impacts - What Really Happened


This activity supports the following National Academy of Sciences Science Education Standards (Grades 5-8):

  • Unifying Concepts and Processes—Systems, order and organization
  • Unifying Concepts and Processes—Evolution and equilibrium
  • Standard C: Life Science—Structure and function in living systems
  • Standard C: Life Science—Regulation and behavior
  • Standard C: Life Science—Populations and ecosystems
  • Standard C: Life Science—Diversity and adaptations of organisms
  • Standard F: Science in Personal and Social Perspectives—Populations, resources and environments
  • Standard F: Science in Personal and Social Perspectives—Risks and benefits


Because some alien species have the ability to create serious problems for their new environments, we tend to think of them all as dangerous. But in fact, many alien species do not last long at all in their new environment. Others prove to be harmless in their newfound habitats. And some even provide significant benefits. Although scientists can never be sure how an introduced species will do in its new home, certain characteristics raise red flags. In this activity, your students will put on their analytical thinking caps to see if they can anticipate how each of the species described ended up affecting its new environment. Then your students will use the answers to see if they can figure out what some of the “red flag” characteristics might be.


Make enough copies of Aliens from the Deep and Alien Impacts so that each student or each team of three students has one.


1. Hand out copies of the Aliens From the Deep comic strip. Have the students read the Aliens From the Deep comic strip. Then have them answer the following questions: What are the aliens in the comic strip called? (Answer: They are a kind of marine snail called RW which in this lesson is short for rapa whelk.) How did they reach the Virginia port? (Answer: They traveled by ship from the Black Sea.) You can discuss how the aliens were discharged along with the ship’s ballast water-water that is taken on by a ship in one port to balance the ship for traveling across the sea. The water is discharged when the ship reaches the new port and unloads its cargo.

2. Discuss alien impacts. Ask the students if they have any idea what will happen to the alien species in the new home. Explain that scientists are never positive about how a species will fare in its surroundings and how much of an effect it will have on its new habitat. For example, some species will simply die off because they do not have the conditions they need to survive. Others (such as oxeye daisies, ginkgo trees and London plane trees) will establish a population in their new surroundings without significantly altering their ecosystem. And other aliens (such as chickens, wheat and soybeans) may even provide lasting benefits. But some alien species will have a negative effect on their surroundings. Examples in this group include the kudzu vine (which now blankets entire forests in the southern United States-choking out native species), the German cockroach and the Norway rat.

Make sure that your students know that the rapa whelk featured in the comic strip is a real species. Scientists do not yet know exactly what effect the rapa whelk will have on the coastal waters of the Atlantic, but they are concerned that it will be a big problem. That is because it has characteristics that scientists think make a more likely to be a menace. In this activity, your students will be learning more about different alien species and seeing if they can figure out what some of those menacing characteristics are.

3. Hand out Alien Impacts worksheet. Give a worksheet to each student or, if you prefer, to each group of three students. Tell the students that they will be making a two-part comic strip of one of the scenarios on the handout. (You can assign the scenarios or allow the students to select the one they prefer.) In the first part of their comic strip, they should illustrate the information provided. Tell them to use the picture to create a good cartoon likeness of the species described. They may want to find other illustrations or photos of their species to complete their cartoons. They could also create a map to show the locations of the origin and of the new home of the species. Encourage the students to have fun with the comic strips, exaggerating characteristics for effect, making the scenes very active and exciting.

4. Share comic strips. Have at least one student share his or her comic strip for each species on the Alien Impacts sheet. Have the students speculate what might have happened next. Ask for a rationale for each idea and a prediction about the impact the alien introduction would have. Share the information about What Really Happened after each species has been discussed. For the second part of the comic strip, have the students illustrate what happened following the alien introduction in the first part of their comic strips.

5. Review characteristics of a problem-causing alien species. As a group, ask the students to think about some of the characteristics that led certain species to become a nuisance. Ask for a volunteer to record the answers on the board. The answers might include, but are not limited to, the following:

  • reproduces rapidly (e.g., Hydrilla, green crab, nutria)
  • easily adapts to a variety of habitats (e.g., Hydrilla grows in many kinds of water bodies and does especially well in lakeside habitats; nutria can live in freshwater and saltwater habitats)
  • eats a lot or eats many different kinds of organisms (e.g., Nile perch, green crab, nutria)
  • has the ability to move quickly and easily (e.g., green crab juveniles are very mobile for 80 days; on the other hand, the black-tailed jackrabbits’ movements were constrained by roads or water on all sides)
  • has very few predators (e.g., Nile perch, green crab)
  • is living in an environment that has already been significantly changed by humans (Some scientists speculate that disturbed habitats are more likely to suffer from the introduction of alien species such as purple loosestrife.)

You should remind your students that scientists still cannot really predict whether an alien species will flourish or fizzle out in its new habitat. But the characteristics listed above are red flags-indications that a species is more likely to be a problem than not!

6. Discuss alien species around the world. Ask your students if they were surprised by the impacts that some of these alien species had on their environment. Then explain that some scientists think that alien species are one of the most significant causes of species decline worldwide. Some scientists think that alien species might even be more of a problem for threatened and endangered species than habitat loss or pollution. Aliens are contributing to species loss and ecosystem changes in both terrestrial and aquatic environments in every part of the world.

In addition, alien species are causing billions of dollars of damage each year to people by wreaking havoc on fisheries, damaging equipment, requiring expensive cleanups and so on. Have your students heard much about alien species in their area? Encourage your students to collect information or articles about alien species in your community or region.

7. Describe the final assignment. As an in-class exercise or as a homework assignment, have the students imagine they are asked to assess the likely threat of the alien species in the Aliens From the Deep comic strip. What things would they need to know about the species to complete their assessment? (Answers will vary but may include: what it normally eats, whether those foods are available in the Atlantic port, which other organisms it is now consuming, how rapidly it reproduces, how it moves, whether it has any local predators, whether others of its species have ever been seen in these or nearby waters and so on.)


Using the student created comic strip, consider the concepts of:

  • how the species was introduced
  • the behavior of the species in the new environment
  • the reasoning used by the student

Needs Improvement—Addresses only one or two of the criteria or is not adequate in addressing any one of the three.

Satisfactory—Adequately addresses all three criteria.

Excellent—Reveals scientific method in thinking through the introduction, the behavior and the impact of the species on the environment.


  • Students can conduct further research on one of the species described briefly in the Alien Impacts worksheet. Have students use the Internet, books, newspapers and other sources to round out their research.
  • They may also want to contact resource managers working at government agencies, such as the US Fish and Wildlife Service or US Department of Agriculture, to gather information on these alien species.


Activity adapted from Oceans of Life–An Educator’s Guide to Exploring Marine Diversity, a resource of World Wildlife Fund’s Windows on the Wild biodiversity education program. For more information on WOW please visit www.worldwildlife.org/windows

Note to Teachers: This lesson and others relating to National Geographic’s Strange Days on Planet Earth can be found online at www.pbs.org/strangedays/

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