Lecture Notes: Determining Heart Rate of Daphnia magna

Presenter:

• Zahra Ghacemi, Biologist

Subject:

• Determination of normal heart rate of Daphnia magna

Overview of Daphnia magna:

• Commonly known as water flea
• Type: Crustacean
• Habitat: Lakes or freshwater environments
• Role: Food source for fish
• Size: 2 mm to 5 mm in length

Observation Process:

• Location: Under a compound microscope on a depression slide
• Body features observed:
  • Transparent body
  • Compound eye
  • Antennae
  • Abdominal legs
  • Intestine
  • Heart located at the back of its body

Procedure to Determine Heart Rate:

• Method:
  1. Place Daphnia in water on a depression slide
  2. Observe under a compound microscope
  3. Add three drops of water to Daphnia
  4. Count heartbeats following a beep sound
• Calculation of Heartbeats Per Minute (bpm):
  • Multiply the number of heartbeats counted in 15 seconds by 4
  • Example Calculation:
    • If 20 beats are counted in 15 seconds, bpm = 20 * 4 = 80
  • Note: Actual Daphnia heart rate is typically faster*

Task:

• Count the heart rate two more times for 15-second intervals
• Calculate the average heart rate per minute
• Complete the data sheet

Conclusion:

• Video intended to assist in understanding and calculating Daphnia’s heart rate
• Encouraged to re-watch the video for clarity

Closing:

• Thank you for watching
• Hope the information was helpful