h Add pond water at a different temperature to the Petri dish. Pasteur pipette (for water from the Daphnia culture tank), Chemicals that may affect the heart rate – at low concentrations (Note 4), Water from Daphnia culture tank at different temperatures – 0 °C (in an ice bath), 10 °C (by adding ice to a water bath), 20 °C, 30 °C and 40 °C (in water baths) (Note 2), Ethanol, 1% and 10%, 10 cm3 of each (Note 3). Above 40 °C and 50 °C, the relation between the two rates will not hold because of the deleterious effects of extreme temperature. Data Table The effect of salt concentration in water on daphnia's heart rate. This report presents the physiological changes in the heart rate of a fresh water crustacean Daphnia magna when exposed to caffeine and alcohol. Ethanol: Ethanol slows heart rate. Different Daphnia magnas were placed in a depression slide containing fresh water and later exposed to solutions of caffeine and alcohol. Daphnia heart rate test is the most common test done using this organism. Interesting Facts about Daphnia - summary Daphnia are often called water fleas because they swim in a jerky motion. A collection of experiments that demonstrate biological Aspirin (o-acetylsalicylic acid) is harmful if swallowed, but a soluble tablet dissolved according to the manufacturers’ instructions would give a suitable concentration to use in the investigation at low hazard to the students. A piece of wool is teased and made into a small loop However, because it is difficult to perform experiments of this nature on humans and get accurate results, we decided to use Daphnia Magna as a substitute for a human. i Record the heart rate again as in step e. j Plot a graph of mean frequency of heart beats per minute against temperature. Read our standard health & safety guidance. In this study, we measured the effect of two different chemicals on the heart rate of Daphnia by comparing the heart rate of the Daphnia before and after the addition of each chemical. Daphnia is a crustacean in the phylum Arthropoda. Introduce lab to students by telling them they will explore the effects of various chemicals (drugs) on an organism’s heart rate. This will gradually heat the water in the dish, and the cardiac frequency can be estimated at 5 °C or 10 °C intervals. would result in a heart rate comparable to the base heart rate of D. magna. Class results for the heart beat at any temperature should be recorded and mean results (and standard deviation) calculated. I monitored their heart rate by examining the Daphnia magna under a microscope and counting the beats per 15 seconds; this was then converted to beats per minute. D. magna is a useful model organism for cardiovascular function, due to its physical transparency and susceptibility to cardioactive drugs known to affect the human heart. It is believed that most physiological processes take place more rapidly at hi… Ingrid Schoonover General Biology II February 15, 2019. Mix well. Students can readily follow this procedure working in pairs. Key among them includes caffeine, alcohol, acetylcholine, epinephrine and temperature. There has been several debates on Caffeine and the possible dangerous effects it could have on the heart when consuming too much. k Take a large Daphnia from the stock culture and record its heart beat at room temperature in pond water (as in step e). Despite this, aspirin has beneficial effects in the heart. From tiny Daphnia magna to humans and other mammals, heart rate is a quantitative characteristic for several species. Because of the variability of results between individual Daphnia, it is not appropriate to draw conclusions from one set of results; each pair (or group) of students should carry out more than one investigation to contribute to the class set. I slipped it under the microscope. This means that, as well as beating faster, the heart's individual beats are associated with an increased volume of blood ejected into the circulation per unit time. The outer carapace of a Daphnia is transparent so all the internal organs, even the beating heart, can be seen. To learn to identify stimulants and depressants by their effect on the heart rate of Daphnia. Daphnia bodies changes with environmental changes as they are ectotherms thus very ideal for testing the heart rate. Daphnia magna is mainly recognized as a freshwater cladoceran, but there are some strains that grow in brackish waters. L-adrenaline (epinephrine) is toxic by inhalation, in contact with the skin and if swallowed. In order to see this effect of temperature, we examined the heart rate of a Daphnia magna over a range of different temperatures. Introduction Daphnia magna are an established model in ecology for the investigation of toxins in freshwater systems, as well as an emerging model in medical science. Caffeine has additional effects on the heart. D. magna were exposed for 2 h to verapamil from 10 −7 to 10 −4 M. Mean±S.E.M. The safest, most hygienic and most convenient ways to provide the necessary food for a colony of Daphnia is to feed them on a few drops of a suspension of fresh yeast or of egg-yolk medium (made by blending a hard-boiled egg in 500 cm3 of water). I had just put one urea-exposed Daphnia on a slide. Then cAMP levels increase and this increases the electrical activity of the sinoatrial node, making it depolarize and 'beat' faster. I had the microscope on the lowest magnification so that I could see all of the Daphnia. There will be considerable variation in the data gathered. In each case, add one drop to 5 cm3 of water before applying to the Daphnia. The green microalga Ankistrodesmus falcatus was fed at optimal co … Campbell et. 1. Student Lab Sheet. SAFETY: Take care handling any chemicals that might affect the heart rate of Daphnia. This is because the animal doesn’t have the capability of regulating its body systems to keep a constant body temperature. 0.3 g in 1000 cm3 of water is similar to the concentration of caffeine in an ordinary cup of coffee or a cola drink and so is low hazard for the students (see also Hazcard 103).