Graphing Respiration In Fish

Background

Respiration is the process of using a gas to convert food into energy. Many people confuse breathing with respiration, but breathing is just the first step of respiration. Respiration is a function of life, which means it is carried on by all living things. Does this mean fish breathe and respire? Of course they do, fish are adapted to taking dissolved oxygen out of the water with their gills. In this lab you will observe the effect of temperature on the respiration of fish.

Objectives

Practice of accurate metric measurement of length, mass, and temperature
Demonstrate the ability to make written observations of the behaviors of fish
Maintenance of the control toad
Careful handling of the equipment
Effective collecting and graphing of data

Materials

Metric Ruler
Visible clock or timer
Source of crushed ice and warm water
Goggles
Beakers for distributing the ice and warm water
Two enclosures for fish (400mL Beakers)
Two goldfish
Two thermometers
Graph paper

Procedures

1.Goggles and Apron are required.

2.Locate the mouth of the goldfish. Every time the mouth opens, the goldfish has taken a breath.

3.Label the two separate containers with your goldfish "Control" and "Experimental". Fill them to approximately 300mL. Record the temperature in each container, they should be the same. Record your data.

4.Have your partner time you for 30 seconds while you count the amount of times the fish breathes. Multiply that number by two to find the amount of breaths per minute. Repeat your timings five times and take an average for each goldfish. Record your data.

5.Once completed, add a few ice cubes to the water, until the temperature has decreased three degrees. Gently stir the water after adding the ice cubes--without unnecessarily agitating the fish.

6.For every three degrees you lower the water temperature, record the fish's respiration and any other behaviors. Do not alter the control's water temperature but measure its temperature and the respiration rate when you measure the experimental.

Caution: Wait five minutes before you change the temperature of the water. You may drop the temperature no lower than 15 degrees Celsius.

7.Once your experimental has reached near 15o C warm the water gradually--in increments of 3 degrees--to the original temperature. Don't forget to record your data.

8.Measure the length (in cm) of your fish by placing your fish on a damp paper towel. Measure from the tip of the nose to the beginning of the tail.

9.Be sure and return your fish to the aquarium. Clean out their containers and put all equipment in its proper place. Be sure and clean your hands with soap and water.

Data & Observations


CONTROL FROG

        Temperature

        Respiration

        Behavior






EXPERIMENTAL FROG

        Temperature

        Respiration

        Behavior

Questions

1.Use the graph paper provided to plot the graph of respiration vs temperature. (Hint: Put temperature on the horizontal axis) What is there a relationship between respiration and temperature?

2.What is the relationship between fish behavior and temperature?

3.Why did you stir the water in step #5?

4.Warm water can hold more dissolved oxygen than cold water. Remember that fish need oxygen for respiration. How can you explain what you observed happening to the fish when the temperature of the water was decreased?