The dinoflagellates constitute a group within the protistan supergroup Alveolata, and can be referred neither to the plant nor the animal kingdom. They swim about using two flagella and are able to orient using various stimuli. About half the living dinoflagellate species are capable of oxygenic photosynthesis, but most of them complement this with capture of prey. Some live ebtirely by capturing small organisms, others are parasites. Some species are able to emit light. The group has a long evolutionary history, and almost as many extinct species as extant ones have been described. Most remarkable is the way the photosynthetically potent dinoflagellates have aquiered their chloroplasts by endosymbiosis with photosynthetic organisms from many different groups. In some cases repeated endosymbiontic events have taken place.