[2] The ability to form a floating colony is one of the unique attributes of Phaeocystis – hundreds of cells are embedded in a polysaccharide gel matrix, which can increase massively in size during blooms.

[1] This intense Phaeocystis productivity generally persists for about a three-month period, spanning most of the summer in the Southern Hemisphere.

Phaeocystis may have negative effects on higher trophic levels in the marine ecosystem, and consequent impacts on human activities (such as fish farming and coastal tourism), by forming odorous foams on beaches during the wane of a bloom.

[4] The ability to form large blooms and its ubiquity make Phaeocystis an important contributor to the ocean carbon cycle.

[14] Genome comparison has shown that the RUBISCO spacer region (located in the plastid DNA, between two subunits of the enzyme 1,5 -bisphosphate carboxylase) is highly conserved among closely related colonial Phaeocystis species and identical in P. antarctica, P. pouchetii and two warm-temperate strains of P. globosa, with a single base substitution in two cold-temperate strains of P.

[20] Extreme cellular remodeling is observed in symbiotic Phaeocystis, including a drastic increase in chloroplast number and an enlarged central vacuole.

[18] [19] This phenotypic change is probably induced by the host to increase photosynthetic output by symbionts, but if it renders symbiotic cells incapable of future cell-division, the symbiosis is a dead end for Phaeocystis.