The chrysophyceans (golden algae) are heterokontophyte algae with golden chloroplasts. Many chrysophycean algae are unicellular, but colonial or simple multicellular species are also known. The chrysophycean algae are basically autotrophic but there are many mixotrophic and colorless heterotrophic species. Heterotrophic chrysophyceans such as Spumella and Paraphysomonas play an important role as lower consumers. The chrysophycean algae mainly inhabit in freshwater, but some species (especially heterotrophs) are common in marine.

The cells are naked or covered by scales, lorica or cell wall. The flagellate cell usually possesses two heterodynamic flagella but posterior (no. 1) flagellum is sometimes reduced. Tubular mastigonemes on anterior (no. 2) flagellum possess lateral filaments. Mixotrophic and heterotrophic species engulf particles (e.g. bacteria) through splitted R2 microtubules. Because major photosynthetic carotenoid is fucoxanthin, chrysophycean chloroplasts are golden-yellow in color. Asexual reproduction by means of binary fission, sporogenesis etc. Sexual reproduction has been reported in some species. The chrysophycean algae produce cysts surrounded by siliceous wall, statospore via sexual or asexual reproduction. Statospores form microfossils to be used for paleoenvironmental reconstruction.