The effect of drugs on heart rate: Research experiment The water flea Daphnia pulex (see figure 1) is a small (1.1-3.5mm long ) crustacean commonly found in ponds in the United Kingdom. The full taxonomy of Daphnia pulux is as follows: Kingdom – Branchiopoda Phylum – Diplostraca Class – Cladocera Order – Anomopoda Family – Daphniidae Genus – Daphnia Subgenus pulex Figure 1. Daphnia pulex, showing the clear exoskeleton and inside the body (Cladoceran website 2005) Whilst being crustaceans and having an exoskeleton Daphnia are easy to study as their exoskeleton is actually clear so it is possible to see through it and study the working of the inside of their body. In particular it is possible to see the flow of the circulatory system and the heart beating. Therefore they are useful to test the effects of specific drugs on heartbeat, as it is easy to see the changes via an obvious change in heartbeat. Daphnia have been used in the present experiment as they are readily available and it is simple to study the effects of drugs on their systems.
