|MadSci Network: General Biology|
Dear Georgia and Theresa, The sugar that you gave your Daphnia is a simple carbohydrate. Just like humans Daphnia use carbohydrates for energy. The sugar acted as a stimulant, it is like you eating a chocolate bar as a 'pick me up'. As a whole sugar cube is a huge amount of energy for the daphnia to take at one time, it could be that the heart has to work hard to keep up with oxygen supply needed for the activity caused by the energy. It could be however that the sugar causes an increase in heart rate because the process of digesting all the sugar reqires increased work by the heart. Hope some of this is useful to you
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