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A Class SystemIntroduction

Discover Darwin all over Pittsburgh in 2009 with “Darwin 2009: Exploration is Never Extinct.” Lesson plans, including this one, are available for multiple grades on-line at www.sepa.duq.edu/darwin/education

Goals

1. To introduce the concepts of biological classification and species.2. To use the various animal exhibits at the zoo in order to show students that animals can be classified according to common features. 3. To introduce Charles Darwin’s contributions to modern-day classification systems.

Learning Objectives

1. Students will be able to define species.2. Students will be able to distinguish how biologists in the past classified organisms differently from current biologists. 3. Students will be able to classify objects and animals into their own classification groups.4. Students will analyze what similarities and differences the objects and animals have. 5. Students will identify key characteristics of animals at the zoo.6. Students will examine Charles Darwin’s contributions to modern-day classification systems.

Materials, Resources, and Preparation

1. Read the introductory material provided in this packet to learn more about key concepts such as biological classification and Charles Darwin.2. Make copies of “A Class System Worksheet.”3. Gather string to use in the Pre-Visit Activity. If not using the students’ shoes in the Pre-Visit Activity, gather additional items to use, such as keys, buttons, furniture, coins, paper clips, etc.

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A Class SystemTeacher PagesVocabulary

1. Classification- The assignment of organisms into meaningful categories to make them easier to find, study, identify, etc. 2. Scale of Nature- A linear, hierarchical classification of animals arranged in order of complexity. Introduced by Aristotle, this biased scale has since been replaced with Darwin’s more objective phylogenetic model. 3. Evolution- The accumulation of changes through inheritance within a population that occurs over a series of generations.4. Phylogentic Model- A model that classifies evolutionary relationships among a range of species by determining common ancestry. 5. Animal Kingdom- The taxonomic group for all multi-cellular organisms that rely on other organisms for nourishment, digest food internally, and lack cell walls.6. Biological Classification or Taxonomy- The method by which biologists group organisms, consisting of the following categories: Kingdom, Phylum, Class, Order, Family, Genus, Species. This method takes into consideration morphological, genetic, and evolutionary similarities.

Overview

Life is diverse! How do scientists organize so much diversity? You don’t need to go to the African Savannah or a coral reef to see that the world is full of diverse plants, animals, and microorganisms. The first system used to organize all living organisms was called the Scale of Nature. The ancient Greek philosopher Aristotle created this sytem in which species were placed in order of increasing “complexity,” a very subjective characteristic. The Scale was often represented by a set of steps, with one organism placed on each step to suggest the superiority of organisms at the top and inferiority of organisms at the bottom. Similarly, humans were always placed at the top to highlight their superiority. There was no clear evidence to justify where plants and animals were placed on this scale.

Aristotle’s Scale of Nature placed humans at the top to suggest their superiority over other organisms.

Copyright 2008, all rights reserved. Visionlearning, Inc. From Charles Darwin III, http://www.visionlearning.com/library/module_viewer.php?mid=112

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Charles Darwin, a naturalist, was one of the first scientists to question the Scale of Nature. While observing nature, he found that some groups of animals challenged the Scale. For instance, in his travels he passed by the Galapagos Islands, where he found twelve species of finches that lived on different islands but seemed very similar to each other. The similarities between the species made him think that some species were more related to each other than to all others. Darwin hypothesized that the twelve kinds of finches all descended from one species, which had migrated amongst the various islands and changed over time into distinct species. The finches were then closely related to each other, because of their shared common ancestor. Identifying the common ancestors between different species, and discovering how all living things are connected, became the cornerstone of the principle of Evolution.

Copyright 2008, all rights reserved. Visionlearning, Inc. From Charles Darwin III, http://www.visionlearning.com/library/module_viewer.php?mid=112

The Phylogenetic model, which is used today, is a diagram that helps scientists translate how species are related by evolution. Using a tree, like the one shown here, allows for identification of the most recent common ancestor. For example, humans share a more recent common ancestor with the chimpanzee than with the gibbon! The studies of Darwin and many other scientists form the basis for the classification system used today, called taxonomy. Taxonomy does not use complexity because there are no objective criteria to define the overall complexity of an organism. Instead, the criteria are based on morphological, evolutionary, and genetic similarities between species. These criteria categorize all living things into a series of nested groups called kingdom, phylum, class, order, family, genus, and species. A kingdom is the broadest group, such as animalia (the animal kingdom). A species is the most specific group, such as tamiasciurus hudsonicus (the American Red Squirrel). The kingdoms are defined by some basic questions, such as: What type of cells make up the organism? How does it get the energy it needs in order to function? Is it made up of one cell or many? The answers to these questions help taxonomists place organisms into the correct kingdoms. Dividing animals into species is more difficult, as scientists have struggled with a meaningful classification system for centuries. The modern definition of species is a group of organisms that are capable of breeding with other members of the same group but are unable to produce fertile offspring with other organisms. However, the lines between species are not concrete, and each scientist must ask questions about the organisms they are sorting in order to categorize them.

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A Class SystemPre-VisitIntroduction

1. Discuss how we use classification systems in everyday life.2. Ask students if they know why we classify things.3. Ask students if they can name a classification grouping that people commonly use.4. Answers will vary, but could include “vegetables, parts of speech, cars, etc.”5. Be sure to tell students what classification is.6. Tell students that now they will do a fun activity with classification.

Activity - Part A.

1. Tell each student to take off his or her shoes.2. Tell the students to arrange the shoes in order of complexity. 3. This will be very arbitrary. Let the students decide or even debate about what it means to have a “complex” shoe.4. Encourage them to question the criteria.

Lecture - Part A.

1. Tell students to think about how many different kinds of animals there are. There are millions of different kinds of animals, and scientists have developed a method to classify organisms.2. Tell students how scientists classified organisms in the past.3. Tell students that before Charles Darwin, a famous biologist, scientists believed that there was only one model to explain species’ relations to one another. They called this model the “Scale of Nature.” This Scale arranged all living things in order of complexity. In this model, species were permanent, and did not change over time or evolve, or become extinct. 4. Show students that the model for the Scale of Nature looked like a set of stairs, with the least complex at the bottom and the most complex at the top. 5. Tell students that this classification system was not useful because, just like when they tried to line up their shoes in order of complexity, there was really no evidence as to why the shoes should be classified in this way - just like there was little evidence to classify animals like this.6. The Scale seemed more useful to make Man seem more important than other life forms!7. Draw the Scale of Nature on the board.

Time: 40 minutes

Materials: - Students’ Shoes- String

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Activity - Part B.

1. Next, have students work as a class or in groups to develop more meaningful classifications for the shoes.2. Tell students to think about what the shoes have in common and what makes each one unique.3. Students can divide the shoes into groups of left shoes and right shoes as well as into types of shoes (sandals, sneakers, etc.)4. Encourage the students to think about subgroups within bigger groups. At first, the groups should be large and should gradually get smaller. Eventually there should be a classification group for each shoe. For instance, there should be a group for the sneaker with shoe strings that are black. This sneaker might also be found in a larger group that contains all sneakers.5. Use string to “section off” various categories.6. Afterwards, leave the shoes in place and tell students that scientists classify animals similarly.

Lecture - Part B.

1. Tell students that a famous scientist named Charles Darwin went on a voyage to the Galapagos Islands where he observed different species of birds that were very similar but lived on different islands. The Scale of Nature could not explain this type of variation.2. Darwin could not “rank” the species in a Scale of Nature because he didn’t feel that any species was better than another one.3. The wonderful variation of these birds baffled Darwin and planted the idea that some of these species were more closely related than others.4. Darwin sketched the diagram below to express the idea that some species are more closely related than others.5. Darwin hypothesized that these species shared a common ancestor – all these species descended from one single species that had been divided up amongst various islands, and changed overtime into distinct species. This concept became the cornerstone of the Principle of Evolution.6. Tell students that the Phylogenetic model, which is used today, rather than the Scale of Nature, does not assume a hierarchy or lower and higher organisms but instead focuses on the similarities, morphological and evolutionary, between species.7. The important thing about this Tree of Life is that it shows how all living things are interconnected and does not rank any living thing as being superior or inferior, like the Scale of Nature.8. Using a tree, like the one above, lets you identify the most recent common ancestor. So, for example, humans share a more recent common ancestor with the chimpanzee than with the gibbon!9. Tell students that they will learn more about animal classification during and after their trip to the Pittsburgh Zoo.

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This drawing was one of Darwin’s original sketches that he used to

determine evolutionary relationships.

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A Class SystemVisitActivity

1. Before going on the visit to the zoo, look at the list of animals on the next page and assign each student or each group of students a different animal in the zoo. Make sure at least 10 animals are covered. See the suggested list.2. Give each student or each group of students an index card. Have the students label along the side #1-6. Explain to the students that they will answer the questions from the worksheet by writing the answers they find on the index card.3. Questions ask about where it lives, how it travels, if it has feathers, fur, scales, etc.4. Students will answer the questions on the index card and will also draw their animal on the opposite side of their index card.

5. Collect all of the index cards for classroom use.

Time: 120 minutes

Materials: - Index Cards- “Do You See What I See Worksheets”- Pencils

Suggestions:- Stop at the Phylogenic Tree Mural while at the zoo.

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List of Animals

Amur tiger Komodo dragon West African dwarf crocodile Black rhino African lion Grant’s zebra Ostrich African elephant Masai giraffe African painted dog Ring tailed lemur Mandrill Bornean orangutan Western lowland gorilla Kodiak bear Leaf-nosed bat and Jamaican fruit bat Timber rattlesnake Gila monster Colorado river toad Beaver California sea lion Eastern grey kangaroo Polar bear Northern sea otter Bullfrog Electric eel Cardinal tetra King penguin Zebra shark Weedy sea dragon

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A Class SystemPost-VisitActivity

1. Pass out the index cards to the students. Tell them that they will make their own classification groupings. 2. Suggestions may include: all the animals that have feathers, all of the animals that have feathers and live in the African Savanna, etc.3. Be sure the students group animals with common features.4. Suggest to students to make groupings based on what they remember from their visit at the zoo. For instance, animals that are taller than the students or shorter than the students.5. After groupings are finished, ask questions to evaluate student learning, such as “Why did you place this animal in this category?” or “How did the information you learned at the Zoo make your classification systems better?”6. Note that the criteria the students used may not be the same criteria used by scientists, but the process is very similar. Remind your students of the phylogenetic tree and modern taxonomy terms introduced earlier. 7. Scientists are always refining the categorization of all living things into groups and sub-groups that signify meaningful relationships.8. All animals have been grouped into the Animal Kingdom.9. Explain to students that scientists have struggled with creating a meaningful classification system for centuries.10. Tell students the current biological classification system groups species based on their morphological similarities, much like the work done in our class today.11. To improve our notion of “similarities,” scientists are also studying evolutionary relationships between species (as suggested by Darwin) and, with the advent of modern biology, genetic similarities.12. Review the concept of evolution if necessary.13. Introduce the biological classification system: Kingdom, Phylum, Class, Order, Family, Genus, Species14. Tell students that you will show how a squirrel fits into this system as an example. A squirrel is an animal that has a backbone. It nurses its young. It has long, sharp front teeth and a bushy tail. It climbs trees, and has brown fur on its back and white fur on its underparts.

Time: 40 minutes

Materials:- Index Cards- Worksheet with questions

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15. Write out the classification of a squirrel on the board:

Kingdom: Animalia - “animal”

Phylum: Chordata - “has a backbone” Class: Mammalia - “nurses its young”

Order: Rodentia - “has long, sharp front teeth” Family: Scuridae - “has a bushy tail”

Genus: Tamiasciurus - “climbs trees”

Species: hudsonicus - “has brown fur on its back and white fur on its underparts”

16. Tell students that an easy way to remember the groupings is: Kings Play Cards On Flat Green Stools17. Tell students that this is how a squirrel is classified and that all other animals are classified similarly.18. Remind students of the activities with the shoes and the classification of the animal index cards. Tell students that at first they had a large grouping (like the animal kingdom), yet they were able to come up with more and more categories to sort the shoes/animals, until each one had its own category.19. Be sure to make the connection between the larger grouping with “kingdom” and smaller groups with smaller ranks, and how they are nested with each other. You can also identify the grouping “species” as the smallest group created by your classroom.

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A Class SystemWorksheet

Directions:

1. Number 1-6 on your index card. 2. Write the name of the animal assigned to you on your card. 3. Answer as many questions from this worksheet as you can on your index card. 4. After you are finished answering the questions, draw your animal on the back of the card. 5. When you are all finished, give your index card back to your teacher.

Questions:

1. Does your animal live on land, in water, or both? 2. Does your animal have feathers, fur, or scales? 3. How does your animal travel? Does it walk, fly, swim, etc.? 4. Does your animal breathe with lungs, gills, or both? 5. Does your animal lay eggs or give live birth? 6. Does your animal eat meat, vegetation, or both?

Example:

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A Class SystemAnswer Key

Animal

Does your animal live on land, in water, or both?

Does your animal have feathers,

fur, skin, or scales?

Does it walk, hop, climb, fly, or swim?

Does your animal

breathe with lungs, gills, or both?

Does your animal lay eggs or give live birth?

Does your animal

eat meat, vegetables, or both?

Amur Tiger Land Fur Walk Lungs Live Meat

Komodo Dragon Land Scales Walk Lungs Eggs Meat

West African Dwarf Crocodile Both Scales Walk/Swim Lungs Eggs Meat

Black Rhino Land Fur Walk Lungs Live Vegetables

African Lion Land Fur Walk Lungs Live Meat

Grant’s Zebra Land Fur Walk Lungs Live Vegetables

Ostrich Land Feathers Walk Lungs Eggs Both

African Elephant Land Fur Walk Lungs Live Vegetables

Masai Giraffe Land Fur Walk Lungs Live Vegetables

African Painted Dog Land Fur Walk Lungs Live Meat

Ring Tailed Lemur Land Fur Walk/Climb Lungs Live Vegetables

Mandrill Land Fur Walk/Climb Lungs Live Both

Bornean Orangutan Land Fur Walk/Climb Lungs Live Vegetables

Western Lowland Gorilla Land Fur Walk/Climb Lungs Live Vegetables

Kodiak Bear Land Fur Walk Lungs Live Both

Leaf-nosed Bat and Jamaican

Fruit BatLand Fur Fly Lungs Live Vegetables

continued on page 12

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Animal

Does your animal live on land, in water, or both?

Does your animal have feathers,

fur, skin, or scales?

Does it walk, hop, climb, fly, or swim?

Does your animal

breathe with lungs, gills, or both?

Does your animal lay eggs or give live birth?

Does your animal

eat meat, vegetables, or both?

Timber Rattle Snake Land Scales Crawl Lungs Live Meat

Gila Monster Land Scales Walk Lungs Eggs Meat

Colorado River Toad Both Skin Walk/Swim Lungs Eggs Meat

Beaver Both Fur Walk/Swim Lungs Live Vegetables

California Sea Lion Both Fur Walk/Swim Lungs Live Meat

Eastern Grey Kangaroo Land Fur Walk/Hop Lungs Live Vegetables

Polar Bear Both Fur Walk/Swim Lungs Live Both

Northern Sea Otter Water Fur Swim Lungs Live Meat

Bull Frog Both Skin Hop/Swim Lungs Eggs Meat

Electric Eel Water Skin Walk Gills Eggs Meat

Cardinal Tetra Water Scales Swim Gills Eggs Meat

King Penguin Both Feathers Walk/Swim Lungs Eggs Meat

Zebra Shark Water Scales Swim Gills Eggs Meat

Leafy Sea Dragon Water Scales Swim Gills Eggs Meat