THE STUDY

How do harp seals stay warm in Arctic water?

Harp seals spend much of their lives swimming in extremely cold water while maintaining a much warmer internal body temperature.

Their thick layer of blubber provides insulation around the trunk, while their flippers contain specialized blood vessels that allow heat loss to be regulated.

Researchers investigated how different parts of the harp seal's body transfer heat as the temperature of the surrounding water changes.

WATER TEMPERATURE 1–24°C

02

EXPERIMENTAL SETUP

UNDERSTAND THE EXPERIMENT

What did the researchers change and measure?

Examine the experimental design before identifying the independent and dependent variables.

EXPERIMENT Harp seal in controlled water

CHANGED

Water temperature

Researchers deliberately changed the surrounding water temperature.

1°C

24°C

1°C 5°C 10°C 15°C 20°C 24°C

Harp seal used in the heat transfer experiment

MEASURED Trunk heat flux

Rate of heat transfer from the trunk.

MEASURED Flipper heat flux

Rate of heat transfer from the flipper.

EXPERIMENTAL DESIGN

What happened in the investigation?

CHANGED Independent condition

↔

Water temperature

Varied from 1°C to 24°C.

MEASURED Researchers recorded

01

Heat flux

Heat transfer from the trunk and flippers.

02

Blubber temperature

Temperature gradients through the blubber layer.

03

Metabolic rate

Rate of metabolic energy production.

THINK LIKE A SCIENTIST

The variable that researchers deliberately change is the independent variable. A measurement that responds to that change is a dependent variable.

YOUR TURN

Identify the variables

Use the experiment above to identify the variable that was changed and the measurement used to investigate heat transfer.

1

Which variable was deliberately changed by the researchers?

2

Which measurement directly showed the rate of heat transfer from different body regions?

03

THE DATA

ANALYZE THE EVIDENCE

What happened as the water became warmer?

EXPERIMENTAL DATA

Harp seal heat transfer

Plot each pair of values on the graph. The highlighted row shows the point you should plot next.

CURRENT DATA POINT Point 1 of 6

Water temperature 1°C

Flipper heat loss 4%

Plot this coordinate on the graph below.

Water temperature (°C)	Flipper heat loss (% metabolic heat production)	Status
1	4	Plot
5	6	Waiting
10	11	Waiting
15	18	Waiting
20	27	Waiting
24	36	Waiting

CURRENT POINT Plot 1°C, 4%

Find 1°C on the x-axis and 4% on the y-axis, then click where the two values intersect.

BUILD THE GRAPH

Plot the experimental data

0 / 6 points plotted

GRAPH AXES

X-axis: Water temperature (°C) · Y-axis: Flipper heat loss (% metabolic heat production)

04

ANALYZE

INTERPRET THE RESULTS

What does the data tell us?

Use your graph and the experimental data to explain how harp seals regulate heat loss.

01

USE THE DATA

Calculate the percentage increase

At 5°C, flipper heat loss was 6% of metabolic heat production. At 24°C, it was 36%.

By what percentage did flipper heat loss increase between 5°C and 24°C?

( 36 − 6 ) ÷ 6 × 100 =

%

02

EXPLAIN THE BIOLOGY

Why does heat loss increase?

Which explanation best accounts for the increase in heat loss through the flippers as water temperature rises?

03

COMPARE BODY REGIONS

Why are the flippers important?

Why can the flippers function as important sites of controlled heat exchange compared with the seal's trunk?

05

CONCLUSION

USE THE EVIDENCE

Build the scientific conclusion

Complete the statement using evidence from your graph and analysis.

SCIENTIST'S CONCLUSION

Choose the correct terms and values.

As water temperature , heat loss through the flippers .

In the educational dataset, heat loss increased from at 5°C to at 24°C.

These results suggest that the flippers act as important sites of , while blubber helps from the trunk.