Interpreting Graphics - Taxonomy

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What is Classification?

To classify means to group ideas, information, or objects based on similarities. Classification is more a part of your life then you might think. Grocery stores, bookstores, and department stores group similar items together. In what other places is classification important?

More than 2000 years ago, Aristotle, a Greek philosopher, developed a system to classify living things. The science of classifying and naming organisms is called taxonomy. Aristotle began his system of taxonomy by dividing organisms into two large kingdoms, the plant and animal kingdoms. A kingdom is the largest of the taxonomic categories. Aristotle then divided the animal kingdom into smaller groups based on where animals live. The plant kingdom was also divided into three groups based on size and structure.

Like Aristotle, Carolus Linnaeus, a Swedish physician and naturalist, created a system to classify organisms based on similarities in body structures and systems, size, shape, color, and methods of obtaining food. Linnaeus’s system gives a two-word name to every organism. They two-word naming system is called binomial nomenclature. Binomial means “two names.” The two-word species name is commonly called the organism’s scientific name or Latin name. The first word of an organism’s scientific name is the genus, and the second is the species. A genus is a group of different organisms that have similar characteristics. A species is the smallest, most precise classification category. Organisms belonging to the same species can mate with one another to produce fertile offspring.

Common Names and Scientific Names

Scientific names serve four basic functions.

1. They help scientists avoid errors in communication.

2. Organisms with similar evolutionary histories are classified together.

3. It gives descriptive information about the species.

4. They allow information about organisms to be organized and found easily and efficiently.

Dichotomous Keys

Scientists classify organisms by using more detailed lists of traits called dichotomous keys. Dichotomous keys used by scientists are arranged in steps with two descriptive statements at each step.

Using a Dichotomous Key

Scientists who classify organisms have made many keys that allow you to identify an organism that may be unknown to you. Try this activity to see how it is done.

Problem

How can a dichotomous key be used to identify native cats in the United States ?

Materials

paper and pencil

Procedure

1. Look at the cats pictured below.

2. Begin with Step 1 of the key to the right. Identify the cat labeled A.

3. On your paper, write the common and scientific names for the cat.

4. Use the same procedure to identify the species of the cat labeled B.

Analyze

1. According to the key, how many species of native cats reside in North America?

Conclude and Apply

2. How do you know that this key doesn’t contain all the species of native cats in the world?

3. INFER why you couldn’t identify a fox using this key.

4. EXPLAIN why it wouldn’t be a good idea to begin in the middle of a key, instead of with the first step.

KEY TO NATIVE CATS OF NORTH AMERICA

1a If the cat has a short tail, go to step 2.

1b If the cat has a long tail, go to step 3.

2a If the cat is distinctly mottled with long ear tufts tipped with black, and no cheek ruff, it is a lynx, Felix lynx.

2b If the cat has indistinct spots, short ear tufts, and a broad cheek ruff, it is a bobcat, Felis rufus.

3a If the cat has a plainly colored body go to step 4.

3b If the cat has a patterned body, go to step 5.

4a If the cat is yellowish to tan above with white to buff below, it is a mountain lion, Felis concolor.

4b If the cat is either brown or black all over the body, it is a jaguarondi, Felis yagouarundi.

5a If the cat has a patterned body with tan and black, go to step 6.

5b If the cat has black-bordered brown spots, tending to form lines on the body, it is an ocelot, Felis pardalis.

6a If the cat is large, spotted with black rosettes or rings in horizontal rows, it is a jaguar, Felis onca.

6b If the cat is small, with irregularly shaped spots and four dark-brownish stripes on the back and one on the neck, it is a margay, Felis wiedii.

A. B.

Interpreting Graphics - Taxonomy

Answer true or false to the following statements.

1. ______ Dogs belong to the order Felidae.
2. ______ A fox belongs to the phylum Arthropoda.
3. ______ Snakes belong to the phylum Reptilia.
4. ______ Lions belong to the class mammalia
5. ______ All arthropods belong to the Class Insecta
6. ______ All rodents belong to the phylum chordata.
7. ______ All amphibians belong to the class reptilia.
8. _______ All primates are mammals.
9. _______ The class mammalia includes dogs, cats and rats.
10. ______ A lion belongs to the genus Felis.
11. ______ All mammals are primates.
12. ______ Insects and lobsters are arthropods.

17. List (use species name) all the animals pictured that belong in the Felidae family.

18. List all the animals pictured that belong to the Carnivora order.

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