Can a Key Be Used to Identify Organisms?




Дата канвертавання27.04.2016
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N ame _______________________________ Period _________
Can a Key Be Used to Identify Organisms?


Classification is a way of separating a large group of closely related organisms into smaller subgroups. The scientific names of organism are based on the classification systems of living organisms. The identification of an organism is easy with a classification system. To identify an organism, scientists often use a key. A key is a listing of characteristics, such as structure and behavior, organized in such a way that an organism can be identified.
A dichotomous key is a classification tool used by field scientists to identify organisms in a set group. They are generally specific for one group and would not work if additional organisms were added. To successfully use a dichotomous key, you must always start with statement one and work through the entire key. If a random statement in the middle of the key is chosen as a starting point, incorrect identifications often result as a key splitting off point has been skipped.








Part 1:

1. Study Figure 1, Shark Anatomy. Each of these structures are key to distinguishing among shark Families.

2. Use Figure 1 as a guide to the shark parts used in the key on page 2.

3. Read statements 1A and 1B of the key. They describe a shark characteristic that can be used to separate the sharks into two major groups. Then study Shark 1 in Figure 2 for the characteristic referred to in 1A and 1B. Follow the directions in the statements and continue until a Family name for Shark 1 is determined. Record the Number/Letter of EACH statement followed in the dichotomous key indicating the sequence of steps followed. (see example on next page) in the data table.

4. Continue keying each shark until all have been identified. Remember, for each one you will ALWAYS start at 1A and 1B!!!! Write the family name in the data table




Shark Anatomy





Shark Family Dichotomous Key
1 A. Body kite like in shape (if viewed from above)………………………………………Go to statement 12

B. Body not kite like in shape (if viewed from above)………………………………….Go to statement 2


2. A. Pelvic fin absent and nose sawlike………………………………………………..Family Pristophoridae

B. Pelvic fin present ………………………………………………………………………..Go to statement 3


3. A. Six gill slits present…………………………………………………………………...Family Hexanchidae

B. Five gill slits present…………………………………………………………………….Go to statement 4


4. A. Only one dorsal fin present…………………………………………………………Family Scyliorhinidae

B. Two dorsal fins present…………………………………………………………………Go to statement 5


5. A. Mouth at front of head rather than back along underside of head………….Family Rhinocodontidae

B. Mouth back along underside of head……………………………………………...Go to statement 6


6. A. Head expanded on side with eyes at end of expansion…………………………….Family Sphyrnidae

  1. Head not expanded………………………………………………………………….…Go to statement 7

7. A. Top half of caudal fin exactly same size and shape as bottom half…………………….Family Isuridae



  1. top half of caudal fin different in size and shape from bottom half…………… Go to statement 8

8. A. First dorsal fin very long, almost half total length of body…………………….Family Pseudotriakidae

B. first dorsal fin length much less than half total length of body………………… ..Go to statement 9
9. A. Caudal fin very long, almost a long as entire body……………………………….Family Alopiidae

B. Caudal fin length much less than length of entire body………………………….Go to statement 10


10. A. Nose with long needlelike point on end………………………………….Family Scapanorhynchidae

B. Nose without needlelike point…………………………………………………..Go to statement 11


11. A. Anal fin absent……………………………………………………………………Family Squalidae

B. Anal fin present…………………………………………………………………..Family Carcharhinidae


12. A. Small dorsal fin present near tip of tail………………………………………………..Family Rajidae

  1. Small dorsal fin absent near tip of tail……………………………………………Go to statement 13

13. A. Hornlike appendages at front of shark………………………………………………Family Mobulidae

B. Hornlike appendages not present at front of shark………………………………….Family Dasyatidae









Have a “fin”tastic day!



Data Table 1

Shark Number Identification Steps Family Name


1



1A, 12A


Rajidae


2









3









4









5









6









7









8









9









10









11









12









13









14









1. What is a classification key and how is it used?

____________________________________________________________________________ ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________


2. What level of classification is each shark identified at?_______________________________
3. Do all of these sharks belong to the same order? ___________ Explain your answer. ____________________________________________________________________________
4. Do all of these sharks belong to the same kingdom? ________ Explain your answer. ____________________________________________________________________________
5. Using the appendix at the back of your book on pp. 1036 – 1045, give the classification levels of the shark indicated below:

Domain ____________________________

Kingdom ___________________________

Phylum ____________________________

Subphylum _________________________


6. Using the information on p. 1044, what characteristics do all of these organisms classified as “cartilaginous fishes” have in common? ___________________________________________ ________________________________________________________________________________________________________________________________________________________


7. Are these traits more specific or less specific than those that place the sharks in the subphylum Vertebrata? __________________________________ Explain your answer. ____________________________________________________________________________ ____________________________________________________________________________
8. What characteristics would you expect sharks to have in common with other members of the Kingdom Animalia? ____________________________________________________________ ____________________________________________________________________________
9. What characteristics would sharks NOT have that insure their classification in the Kingdom Animalia instead of the Kingdom Fungi? ____________________________________________ ____________________________________________________________________________
10. What characteristics do sharks have that place them in the Domain Eukarya? ________________________________________________________________________________________________________________________________________________________
11. List four different characteristics that were used in the shark key to distinguish among families.

________________________________ ______________________________________

________________________________ ______________________________________

12. Which main characteristic could be used to distinguish

a. shark 4 from shark 8? __________________________________________________

b. shark 4 from shark 7? __________________________________________________


13. Below is a diagram of a shark not pictured in Figure 2. Can the dichotomous key be used to identify the family it belongs to? ______________ Explain your answer. ____________________________________________________________________________ ____________________________________________________________________________
14. How would you find the correct family name for this shark using just the diagram given? ____________________________________________________________________________


15. This shark belongs to the Family Stegostomatidae. What levels of classification would you expect it to have in common with the rest of the sharks? _____________________________________________. What additional levels of classification would be unique to this shark as compared to the other sharks in this lab? ____________________________________________________________________________



Part 2 (BONUS—10 pts):

Prepare your own key for the five fish in Figure 3. Use the same format as on page 4. The family names to be used are the numbers I, II, III, IV, V. Your key should correctly use traits that will lead to each fish family. To help you get started, the first statements are given. Statement I divides the five fish into two mains groups, based on body shape. Next, choose another characteristic that will divide the fish not having a tubelike body into two groups. Continue to choose characteristics that will separate a group into smaller groups until only one fish fits those criteria. Write your key in the space below. NUMBER AND LETTER YOUR STEPS!




Figure 3




Key to Fish


1. A. Fish with long tubelike body_________________________Fish I____________________

  1. Fish with body shape not tubelike___________________go to step 2__________________

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


  1. If these Roman numerals represent Orders of fish, what levels of classification would they all 5 have in common? _____________________________________________________________ ____________________________________________________________________________




  1. What characteristics do these fish have that distinguish them from the sharks in Figure 2? (Use the appendix in your book) ______________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________




  1. What levels of classification do these fish share with sharks? ___________________________ ____________________________________________________________________________ ____________________________________________________________________________




  1. What levels of classification do these fish share with Protista? __________________________




  1. How can you distinguish a fish from a bacteria based on the characteristics of the kingdoms? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________






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