Student Worksheet for Activity 9.1.1
Using a Classification Key
Whales are often grouped as either toothed or baleen whales. Baleen whales have
a series of vertical plates that branch and crisscross at the opening of the mouth.
Each plate acts as a filter, straining small marine life from the seawater. In this
activity, you will identify various species of whales using a dichotomous key.
anterior
dorsal fin
mouth
dorsal surface
Procedure
1. Use Figure 6 to help you identify the whale’s body structures referred to in
the key.
2. To identify each whale in Figures 7 to 13, start by reading part 1(a) and (b)
of the key. Then follow the “Go to” direction at the end of the appropriate
sentence until the whale has been properly classified.
ventral
surface
posterior
pectoral
fin
tail fin
Figure 6
Figure 7
• teeth
• adult length:6.0 m (females), 6.7 m (males)
• adult mass: 7.4 tonnes (t) (females),
10.5 t (males)
Figure 10
• teeth
• adult length: 4.2 m (females),
4.7 m (males)
• adult mass: 900 kg (females),
1.6 t (males)
Figure 8
• baleen plates
• adult length: 13.7 m (females), 12.9 m (males)
• adult mass: 25–30 t
Figure 11
• teeth
• adult length:11 m (females),
15 m (males)
• adult mass: 20 t (females),
45 t (males)
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Figure 9
• teeth
• adult length:3.5 m (females), 4.5 m (males)
• adult mass: 1.0 t (females), 1.2 t (males)
Figure 12
• baleen plates
• adult length:26.5 m (females),
25 m (males)
• adult mass: 200 t (females),
100 t (males)
Figure 13
• baleen plates
• adult length:14–15 m
• adult mass: 50–60 t
Unit 4 Lab and Study Masters
4-7
The Key
1. (a) baleen plates
(b) teeth
Go to 2.
Go to 4.
2. (a) dorsal fin
(b) no dorsal fin
Go to 3.
bowhead whale (Balaena mysticetus)
3. (a) long pectoral fin
(b) short pectoral fin
humpback whale (Megaptera novaeangline)
blue whale (Balaenoptera musculus)
4. (a) no dorsal fin
(b) large dorsal fin
Go to 5.
killer whale (Orincus orca)
5. (a) small nose
(b) large projection from nose
Go to 6.
narwhal (Mondon monoceros)
6. (a) mouth on ventral
surface (underside) of head
(b) mouth at the front of head
sperm whale (Physeter macrocephalus)
beluga (Delphinapterus leucas)
Analysis
(a) What are four characteristics used to classify whales?
(b) Why might biologists use a key?
(c) Provide an example of when a biologist might use a key to classify whales.
(d) Make a list of other characteristics that could be used to classify whales.
Evaluation and Synthesis
(e) Research to find out more about whales, for example, their distribution
ranges and whether a species is threatened or endangered.
(f) As a group, give each of the insects (Figure 14) a genus and species name,
and record the names in a notebook. On a separate piece of paper, make a
dichotomous key that allows others in your class to identify each of the
insects.
(i) Hand in the dichotomous key that your group constructed.
(ii) Comment on how successfully another group was at using the key.
What changes would you make to your key?
4-8 Unit 4 Lab and Study Masters
Copyright © 2002 Nelson Thomson Learning
(g) Identify five different trees or shrubs native to your locale and make
a dichotomous key that allows others to identify them.
Figure 14
Various insects
Copyright © 2002 Nelson Thomson Learning
Unit 4 Lab and Study Masters
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