Using a Classification Key Lab

Transcription

1 Using a Classification Key La Discussion Suppose you find a large colorful wildflower while walking through the woods. Chances are the flower has already een named and classified, ut how can you learn its identify? As an aid to help others identify unknown organisms, iologists have developed classification keys. Many classification keys have een developed to help identify wildflowers and many other kinds of plants and animals. Although these keys many vary in purpose and complexity, they have certain features in common. These classification keys are often called dichotomous keys. The word dichotomous comes form the word dichotomy, meaning two opposite parts or categories. A dichotomous classification key presents the user with two opposite statements aout some trait of an organism. By choosing the statement that est descries the unknown organism, the user is led to further pairs of statements. By going from one set of statements to another, the name of the organism or its classification group is finally determined. In this investigation you will use a classification key to identify several organisms. Prolem How can a classification key e used to identify organisms? Directions Use the dichotomous key in figure #1 to determine scientific and common name of each in figure #2. Make sure that you write the scientific name and the common name of the s the appropriate lines of the answer key.

2 Key to the Salamanders: 1 a Hind lims asent Siren intermedia Siren Hind lims present Go to 2 2 a External gills present in adults Neciturus macrolestus Mud puppy External gills asent in adults Go to 3 3 a Large size (over 7 cm long) Go to 4 4 a Small size (under 7 cm long) Go to 5 Body ackground lack, large white spots irregular in shape and size completely covering ody & tail Body ackground lack, small, round, white spots in a row along each side fro eye to tip of tail Amystoma tigrinum Amystoma maculatum Tiger Spotted Salamander 5 a Body ackground lack with white spots Go to 6 6 a 7 a 8 a Body ackground light color with dark spots and or lines on ody Small white spots on a lack ackground in a row along each side from head to tip of tail Small white spots on a scattered throughout a lack ackground from head to tip of tail Large irregular lack spots on a light ackground extending from head to tip of tail Go to 7 Amystoma Jefferson jeffersonianum Plethodon glutinosus Amystoma opacum Slimy Marled No large irregular lack spots on a light ackground Go to 8 9 a 10 a Round spots scattered along ack and sides of ody, tail flattened like a tadpole Without round spots and tail not flattened like a tadpole Two dark lines ordering a road, light mid-dorsal stripe with a narrow median dark line extending from the head onto the tail Without two dark lines running the length of the ody A light stripe running the length of the ody and ordered y dark pigment extending downward on the sides A light stripe extending the length of the ody, a marked constriction at the ase of the tail Triturus viridescens Eurycea islineata Plethodon cinereus Hemideclylium scutatum Newt Go to 9 Two-lined Go to 10 Redacked Four-toed

3 Figure #2 Pictures of Unknown Salamanders

4 Using a Classification Key Write the scientific and common names of each in Figure 1 on the line that corresponds to its numer Question and Analysis 1. As you used the classification key to identify the s, did you go from general to specific characteristics or from specific to general characteristics? 2. What two groupings do the scientific names of the s represent?

5 3. Do you think that there may e some closely related species of organisms that cannot e identified with a classification key? Explain your answer. 4. Why do you think iological classification keys always present two, rather than some other numer, of choices at each step? 5. What types of prolems would scientists have today if Carolus Linnaeus had not developed his classification and naming system of organisms? 6. Explain what is meant y the statement, Classification systems are the inventions of humans; diversity is the product of evolution.