Last Name:
First Name:
Period #
Unit 6: Environmental Science
Dichotomous Keys Packet
Date:
Introduction
Imagine that you’re walking down the street, and you see a leaf on the ground. You want to know that species
of tree it belongs to. What would you do?
You might try to look it up on the Internet. But what if you’re not sure which characteristics of the leaf are
important, and which aren’t? You could search for “green crunchy leaf” but that probably isn’t going to be too
helpful. Besides, the Internet hasn’t always been around! What did scientists do before Google?
A dichotomous key is a tool that scientists use to determine what species something belongs to. Here’s how
they work…
Instructions
A dichotomous key is a tool that asks you questions. “Dichotomous” means “splitting into exactly two different
parts.” So, each question in the dichotomous key has exactly two different possible answers. If youa re using a
dichotomous key to classify something, the rules are simple:
1.
2.
3.
4.
Always start with #1
Pick the correct answer
Next to the correct answer (to its right) are instructions. Follow the instructions.
Keep repeating steps (2) and (3) until you arrive at a final answer.
There is always only one correct answer. That means that if you end up with two classifications, you did
something wrong and need to check your work.
Let’s try out one!
Example
1a. Bean round
1b. Bean elliptical or oblong
Garbanzo Bean
Go to 2
2a. Bean white
2b. Bean has dark pigments
White Northern
Go to 3
3a. Bean evenly pigmented
3b. Bean pigmentation
mottled
(blotches/spotted)
Go to 4
Pinto Bean
4a. Bean black
4b. Bean reddish-brown
Black Bean
Kidney Bean
Question: What species of bean is pictured above?
 Well, the first set of questions asks: is it round (1a) or elliptical/oblong (1b)?
 These are elliptical.
 The instructions say, “Go to 2,” so we will go to the second set of questions.
 (2a) and (2b) ask: is it white or does it have dark pigments?
 It has dark pigments.
 The instructions say, “Go to 3.”
 (3a) and (3b) ask: is it evenly pigmented or mottled (blotches/spotted).
 The beans are mottled (they have blotches/spots), which means that their species is Pinto Bean.
Directions: Use the dichotomous key to the left to identify the Wacky People to the right. Write your final
answers below.
Wacky People Dichotomous Key
1a Two feet
Go to 2
1b Some other number of feet Go to 3
2a Does not look at all human
2b Looks a lot like a human
Go to 4
Go to 5
3a One leg
3b Three or four legs
Go to 6
Go to 7
4a Fly-like
4b Not fly-like
Mosk Cara
Go to 8
5a Seems to be a girl
5b Not a girl
Rita Nita
Go to 9
6a Leg is curled, two feet
6b Leg is straight, one foot
Ru-ela.Brella
Giggles
7a Three legs
7b Four legs
Go to 10
Go to 11
8a Has webbed feet
8b Clawed feet
Hex Oculate
Go to 12
9a Curly hair, no toes
9b Wiggly looking mouth,
three toes on feet
Lugio Wirum
C. Nile
10a Very long nose,
open mouth
10b Some other appearance
Elle E. Funk
Go to 13
11a Has duck bill, two pinchers Tri D. Duckt
11b No arms or pinchers
Go to 14
12a Has ears, tail, and beak
12b Four eyes on stalks
Grif Leon
Eggur Ondy
13a One eye, webbed feet
13b Four stalked eyes,
four pinchers
Cue Kide
Quadrumenox
14a Three toed feet,
nose like a flower
14b Spider-like, has spots
Tunia petalos
Patterned
mulywumpus
A. _______________________
B. _______________________ C. _______________________
D. _______________________
E. _______________________ F. _______________________
G. _______________________
H. _______________________ I. _______________________
J. _______________________
K. _______________________
M. _______________________
N. _______________________ O. _______________________
L. _______________________
Directions: Scientists have discovered quite a few
new creatures on planet Pamishan. They need your
help to identify and classify them. Use the
dichotomous key on the next page to identify these
creatures. Write their final classification under their
picture.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
A Key to New Pamishan Creatures
1. a. The creature has a large wide head
b. The creature has a small narrow head
2. a. It has 3 eyes
b. It has 2 eyes
3. a. There is a star in the middle of its chest
b. There is no star in the middle of its chest
4. a. The creature has hair spikes
b. The creature has no hair spikes
5. a. The bottom of the creature is arch-shaped
b. The bottom of the creature is M-shaped
6. a. The creature has an arch-shaped bottom
b. The creature has an M-shaped bottom
7. a. The creature has hairy spikes
b. The creature has no spikes
8. a. There is a star in the middle of its body
b. The is no star in the middle of its body
9. a. The creature has an arch shaped bottom
b. The creature has an M shaped bottum
10. a. The body is symmetrical
b. The body is not symmetrical
11. a. The creatrue has no antennae
b. The creature has antennae
12. a. There are spikes on the face
b. There are no spikes on the face
13. a. The creature has no spike anywhere
b. There are spikes on the right leg
14. a. The creature has 2 eyes
b. The creature has 1 eye
cyclops
15. a. The creature has a mouth
b. The creature has no mouth
16. a. There are spikes on the left leg
b. There are no spikes at all
17. a. The creature has spikes
b. The creature has no spikes
18. a. There are spikes on the head
b. There are spikes on the right leg
montanian
19. a. There are spikes covering the face
b. There are spikes only on the outside
edge of head
go to 2
go to 11
go to 3
go to 7
go to 4
go to 6
Broadus hairus
go to 5
Broadus archus
Broadus emmus
Broadus plainus
Broadus tritops
go to 8
go to 10
Broadus
hairystarus
go to 9
Broadus
hairyemmus
Broadus kiferus
Broadus walter
Broadus
anderson
go to 12
go to 14
Narrowus wolfus
go to 13
Narrowus
blankus
Narrowus
starboardus
go to 15
Narrowus
go to 16
go to 17
Narrowus portus
Narrowus plainus
go to 18
Narrowus
georginia
go to 19
Narrowus
Narrowus
beardus
Narrowus fuzzus