Characterization of swimming behavior of Daphnia magna in presence of a Dopamine agonist

Daphnia are aquatic microcrustaceans often called water fleas. They are a commonly studied model organism in ecology, ecotoxicology and evolutionary biology. Daphnia swimming behavior is dependent on several factors like body size, light, water temperature, presence of food and predators. They propel themselves through liquid by periodically beating their second antennae in a breaststroke motion which results in directed motion. They can drastically change the direction of their movement by irregular motion of the second antennae. Due to the complexity of their motion, the description of their locomotion has been largely qualitative and vaguely quantitative. Our study creates a granular level quantitative classification of baseline motion parameters in a swimming Daphnia. We further study the impact of a dopamine agonist in the swimming dynamics of Daphnia magna. Application of a D1-dopamine receptor agonist gives rise to a counter-intuitive beat pattern of the organism. We characterize these unique beat patterns of the antenna in untreated daphnids compared to daphnids treated with the agonist . Daphnia motion is studied using high speed imaging, two and three dimensional tracking techniques.