Pre-reading PAG 11.2 – Daphnia
What is the point of this PAG? à to see what effect temperature has on the heart rate of the Daphnia
magna.
1) Use a pipette to capture a single Daphnia (if necessary, cut the pipette at a 45’ angle to prevent
death of the Daphnia).
2) Use the pipette to place the Daphnia in a well on the cavity slide (don’t use a cover slip as this will
also kill the Daphnia.)
3) Clip the slide onto the stage and start with the lowest magnification, increase, and focus until you
can locate the heart of the Daphnia. (Just under the anterior dorsal surface.)
4) Using a stopwatch count the heartbeats by 15 seconds, then multiply the heart beats by 4 to get
BPM (might be easier here to have a piece of paper next to you to put a dot on every beat that a
Daphnia has.)
5) In a beaker add spring water and add several Daphnia, add a thermometer to note the
temperature.
6) Add ice to the bottom of a large beaker, place the small beaker inside the ice breaker… wait until
the temperature reaches the desired one (this method can be done for higher temperatures)
(TURN OFF THE MICROSCOPE WHEN WAITING FOR TEMPERATURE) – because we don’t want the water
well to heat up too quickly as this will alter heart rate as we are measuring it and therefore reduces
validity.
Average Daphnia Heart rate at RTP à 200bpm -332bpm
What is the point of this PAG? à to see what effect temperature has on the heart rate of the Daphnia
magna.
1) Use a pipette to capture a single Daphnia (if necessary, cut the pipette at a 45’ angle to prevent
death of the Daphnia).
2) Use the pipette to place the Daphnia in a well on the cavity slide (don’t use a cover slip as this will
also kill the Daphnia.)
3) Clip the slide onto the stage and start with the lowest magnification, increase, and focus until you
can locate the heart of the Daphnia. (Just under the anterior dorsal surface.)
4) Using a stopwatch count the heartbeats by 15 seconds, then multiply the heart beats by 4 to get
BPM (might be easier here to have a piece of paper next to you to put a dot on every beat that a
Daphnia has.)
5) In a beaker add spring water and add several Daphnia, add a thermometer to note the
temperature.
6) Add ice to the bottom of a large beaker, place the small beaker inside the ice breaker… wait until
the temperature reaches the desired one (this method can be done for higher temperatures)
(TURN OFF THE MICROSCOPE WHEN WAITING FOR TEMPERATURE) – because we don’t want the water
well to heat up too quickly as this will alter heart rate as we are measuring it and therefore reduces
validity.
Average Daphnia Heart rate at RTP à 200bpm -332bpm
