dinoflagellates, these vesicles commonly
contain cellulosic plates arranged in consistent patterns (tabulation patterns). These
patterns provide the primary basis for determining evolutionary relationships within
the group.
About half of living dinoflagellate species are photosynthetic, others are heterotrophic; and some species have both nutritional modes, underlining the futility of attempting to classify these relatively simple
organisms as plants or animals.
Dinoflagellates are today most diverse in
continental shelf environments, but also
occur in oceanic and freshwater habitats.
Some are parasitic and one group, popularly known as zooxanthellae, live
symbiotically in the soft tissue of invertebrates such as corals, giving these animals