The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta, are a clade of algae.

The cryptomonads are a group of algae, most of which have plastids. They are common in freshwater, and also occur in marine and brackish habitats. Each cell is around 10–50 μm in size and flattened in shape, with an anterior groove or pocket. At the edge of the pocket there are typically two slightly unequal flagella.