Daphnia Heart Rate Experiment

1589 words 7 pages
Experiment Report for: ‘the affect of Caffeine on Daphnia’s heartbeat’


Aim: The aim of this experiment is to understand the affect of the drug Caffeine on the rate of a Daphnia’s heartbeat. This is to understand the affect of caffeine on a human’s heart rate and the use of daphnia keeps the experiment fair and safe.

Background Research:

Daphnia –

Daphnia (water fleas) are grouped as crustaceans under the arthropod group of Kingdom Anamalia. They have an open circulatory system where fluid (there is no distinction between blood and nutritional fluid) in the hemocoel delivers oxygen and nutrients to the organs/ cells directly meaning caffeine enters their system much faster than it would in humans. This type of
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Equipment List:

• daphnia (and daphnia tank)

• Tank of fresh pond water

• Microscope

• Cavity slides

• 1ml pipette

• 1ml syringe

• 10ml beaker

• Stop clock

• Pond water & caffeine solution (0.25% and 0.5% caffeine)

• Board marker to dot on table


• Take daphnia from tank in pipette that has end cut off and place in beaker, leave to rest.

• Collect microscope and cavity slides, set microscope to lowest magnification.

• Collect caffeine solution , pond water and a syringe. Take a beaker of the solution to be used first (start with 0.25%).

• Place one daphnia onto a cavity slide and place under microscope. Allow the daphnia to adjust for a minute or two.

• Using the stop clock and board marker, count the daphnia’s resting heartbeat in 15 seconds by drawing dot on the table for every beat (repeat this to get an average). To calculate what it is in a minute do beats per 15 seconds x4.

• Take the daphnia from under the microscope and add some 0.1% caffeine solution to it.

• Place back under the microscope and allow the daphnia to adjust again.

• Using the stop clock and board marker,