What are Daphnia?
Daphnia are semitransparent microcrustaceans that are only 1 to 1.5 millimeters across. Although they are tiny, they are making a huge difference all over the world as a biological model for investigating fundamental mechanisms of inheritance and development, cellular function, physiological systems, immunity response, disease, and macromolecular structure/function relationships.
The reason why we are modeling daphnia is to study its heart, which can easily be seen because of daphnia's transparency. The video below shows a stunning example of a daphnia's heart beating.