Classification Keys

Name: Date: Period:
Classification Keys
Part A Introduction: All cultures have developed names for living things found in their
environments. When various everyday names are used for the same organism in different
cultures, confusion is possible. For example, we know the Robin here
in the United States as a dark gray bird with a red chest and black
head. In England the Robin is known as a light colored tan bird with a
bright orange chest and face. To avoid confusion like this, scientists
have developed an international system for naming and classifying all
organisms. This system often lists organisms by their genus and
species name.
1. Why did scientists develop an international naming system for organisms? _________
_________________________________________________________________
See the order of classification in Figure 1 below. The Kingdom level is the most general while
the species is the most specific. For instance, camels, llamas, giraffes, squirrels, snakes, and
sea stars are all in the Kindgom Animalia (Latin for animals) while camels are the only animal in
the species bactrianus. Notice when we list the Scientific name for an organism the name is
typed in italics (or underlined if handwritten). Organisms are usually referenced by their
genus and species names making the Scientific name for camels Camelus bactrianus or C.
bactrianus. Notice the first letter of the genus is capitalized while the species is not. The
scientific name for humans is Homo sapiens.

Identification guides, called keys, have been developed to help people identify organisms by
scientific name according to the organisms’ characteristics. Keys also aid the in the
classification of organisms and their relatedness. For example, the Bengal tiger (common
name) has the Scientific name Panthera tigris tigris. This tiger is closely related to the
Siberian tiger whose Scientific name is Panthera tigris altaica. Note the Scientific names’
similarity hinting the animals close relatedness.
2. What are the two purposes of a key? _____________________________________
_________________________________________________________________
Classification keys are usually dichotomous in arrangement. The word dichotomous means “two
opposite parts or categories.” A dichotomous key gives the reader a series of opposing
descriptions on the basic features of an organism. The reader studies the specimen and
selects the descriptions that apply to it until reaching a statement that
characterizes only one species and names it by genus and species. In this
investigation you will use a typical dichotomous key to identify the genus and
species of several different organisms.
Figure 2 Dichotomous Key by common name

Part B Using Keys: Below is a diagram of a new alien species, the Pamishans. Use Figure 3
along with Key 1 on the next page to identify the creatures listed below (Individuals #1, 4, 10,
& 19). Write the name of the aliens on the lines below the diagram gathered from the key. To
do this, look at the picture as you read through the steps of Key 1. Start by reading 1a and 1b.
Follow the directions of the characteristics that fit your alien.
Figure 3: Pamishans
1. _____________________________ 4. _____________________________
10. ____________________________ 19. _____________________________

Key 1: Pamishan Alien Key Continue following the correct statements until you have
identified it.
1. a. The creature has a large wide head.......................................... go to 2
b. The creature has a small narrow head....................................go to 11
2. a. It has 3 eyes ..............................................................................go to 3
b. It has 2 eyes ..............................................................................go to 7
3. a. There is a star in the middle of its chest...................................go to 4
b. There is no star in the middle of its chest ................................go to 6
4. a. The creature has hair spikes .........................................Broadus hairus
b. The creature has no hair spikes.................................................go to 5
5. a. The bottom of the creature is arch-shaped .................Broadus archus
b. The bottom of the creature is M-shaped ...................Broadus emmus
6. a. The creature has an arch-shaped bottom ..................Broadus plainus
b. The creature has an M-shaped bottom.......................Broadus tritops
7. a. The creature has hairy spikes ...................................................go to 8
b. The creature has no spikes......................................................go to 10
8. a. There is a star in the middle of its body ...............Broadus hairystarus
b. The is no star in the middle of its body .....................................go to 9
9. a. The creature has an arch shaped bottom ..........Broadus hairyemmus
b. The creature has an M shaped bottom ......................Broadus kiferus
10. a. The body is symmetrical .............................................Broadus walter
b. The body is not symmetrical....................................Broadus anderson
11. a. The creature has no antennae ................................................go to 12
b. The creature has antennae .....................................................go to 14
12. a. There are spikes on the face .....................................Narrowus wolfus
b. There are no spikes on the face ..............................................go to 13
13. a. The creature has no spike anywhere ......................Narrowus blankus
b. There are spikes on the right leg ......................Narrowus starboardus
14. a. The creature has 2 eyes...........................................................go to 15
b. The creature has 1 eye..............................................Narrowus cyclops
15. a. The creature has a mouth........................................................go to 16
b. The creature has no mouth.....................................................go to 17
16. a. There are spikes on the left leg .................................Narrowus portus
b. There are no spikes at all .........................................Narrowus plainus
17. a. The creature has spikes ..........................................................go to 18
b. The creature has no spikes ...................................Narrowus georginia
18. a. There are spikes on the head ..................................................go to 19
b. There are spikes on the right leg........................Narrowus montanian
19. a. There are spikes covering the face .........................Narrowus beardus
b. There are spikes only on outside edge of head .........Narrowus fuzzus

Salamander Key: Figure 4 is a group of salamanders common to the U.S. Use this figure along
with Key 2 to identify the salamanders listed below the key.
Figure 4: Salamanders

Key 2: Salamander Key Begin by reading statements 1a and 1b. One of the statements will
describe your salamander; the other statement does not. Follow the directions for the
statement that applies to that salamander and continue following the correct statements until
you have identified it. The common name follows the Scientific name after the comma.
1 A Hind limbs absent Siren intermedia, siren
B Hind limbs present Go to 2
2 A External gills present in adults Necturus maculosus, mud
puppy
B External gills absent in adults Go to 3
3 A Large size (over 7 cm long in Figure 1) Go to 4
B Small size (under 7 cm long in Figure 1) Go to 5
4 A Body background black, large white spots variable in size
completely covering body and tail
Ambystoma tigrinum, tiger
salamander
B Body background black, small round white spots in a row
along each side from eye to tip of tail
Ambystoma maculatum,
spotted salamander
5 A Body background black with white spots Go to 6
B Body background light color with dark spots and/or lines
Go to 7
on body
6 A Small white spots on black background in a row along
each side from head to tip of tail
Ambystoma jeffersonianum,
Jefferson salamander
B Small white spots scattered throughout a black
background from head to tip of tail
Plethodon glutinosus, slimy
salamander
7 A Large irregular white spots on a black background
extending from head to tip of tail
Ambystoma opacum, marbled
salamander
B No large irregular black spots on a light background Go to 8
8 A Round spots scattered along back and sides of body, tail Triturus viridescens, newt
flattened like a tadpole
B Without round spots and tail not flattened like a tadpole Go to 9
9 A Two dark lines bordering a broad light middorsal stripe
with a narrow median dark line extending from the head
onto the tail
Eurycee bislineata, two-lined
salamander
B Without two dark lines running the length of the body Go to 10
10 A A light stripe running the length of the body and
bordered by dark pigment extending downward on the
sides
Plethodon cinereus, red-backed
salamander
B A light stripe extending the length of the body without
dark pigment on the sides
# Scientific Name Common Name
Hemidactylium scutatum, fourtoed
salamander
5 _____________________________ _____________________________
6 _____________________________ _____________________________
10 _____________________________ _____________________________
11 _____________________________ _____________________________

Analysis Questions: PLEASE WRITE IN COMPLETE SENTENCES!!!!!
1. What are the two purposes of a classification key?
2. From page 1, what two levels from the order of classification are often used to
identify an individual organism?
Give an example.
3. What was the main type of characteristics used in the keys from this packet?
4. Do you think it would be possible to use a characteristic besides physical
appearance when creating a key?
Give an example.
5. If you were going to make a key for the birds in Oak Park, what characteristics
would you use in your key?