Daphnia magna increase feeding activity in the presence of four amino acids

Abstract Daphnia feeding studies have previously demonstrated increased grazing behaviour in response to the presence of food particles. However, it is not resolved whether these behavioural responses are due to chemosensation or another sensory modality as the particle size and electrical charge of algal cells could be confounding factors and may also play a role in finding food. This study has provided evidence on the role of chemosensation in grazing by exposing Daphnia magna to 20 L-isomer amino acids and monitoring changes in mandible rolling, a behaviour associated with feeding in Daphnia. This study has shown that D. magna increase feeding behaviour, i.e. mandible movements, when exposed to the L-isomers of the amino acids aspartate, cysteine, glutamate and glutamine. These results not only provide insight into Daphnia life history but also provide a tool for researchers to study Daphnia chemosensation.