Copyright © 2002 Nelson Thomson Learning Unit 4 Lab and Study Masters 4-7

Student Worksheet for Activity 9.1.1

Using a Classification Key

anterior

ventralsurface

posterior

dorsal surface

mouth

pectoralfin

tail fin

dorsal 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 8

• baleen plates• adult length: 13.7 m (females), 12.9 m (males)• adult mass: 25–30 t

Figure 9

• teeth• adult length:3.5 m (females), 4.5 m (males)• adult mass: 1.0 t (females), 1.2 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 11

• teeth• adult length:11 m (females),

15 m (males)• adult mass: 20 t (females),

45 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

Whales are often grouped as either toothed or baleen whales. Baleen whales havea 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 thisactivity, you will identify various species of whales using a dichotomous key.

Procedure

1. Use Figure 6 to help you identify the whale’s body structures referred to inthe 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 appropriatesentence until the whale has been properly classified.

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The Key

1. (a) baleen plates Go to 2.(b) teeth Go to 4.

2. (a) dorsal fin Go to 3.(b) no dorsal fin bowhead whale (Balaena mysticetus)

3. (a) long pectoral fin humpback whale (Megaptera novaeangline)(b) short pectoral fin blue whale (Balaenoptera musculus)

4. (a) no dorsal fin Go to 5.(b) large dorsal fin killer whale (Orincus orca)

5. (a) small nose Go to 6.(b) large projection from nose narwhal (Mondon monoceros)

6. (a) mouth on ventral sperm whale (Physeter macrocephalus)surface (underside) of head

(b) mouth at the front of head 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 distributionranges 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 adichotomous key that allows others in your class to identify each of theinsects.(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?

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(g) Identify five different trees or shrubs native to your locale and makea dichotomous key that allows others to identify them.

Figure 14

Various insects