Ulvaria obscura is an intertidal and subtidal benthic marine algae found in temperate and Arctic ocean waters around the world.^[1][2]

Ulvaria obscura is a common marine algae, typically identified in algal blooms referred to as “Green Tides”.^[3][4] The species is distinct in its ability to produce the neurotransmitter dopamine as a herbivore defense mechanism.^[5][6] The species has a wide tolerance to various growth conditions, surviving temperatures between 5-29 °C, salinities from freshwater to complete saturation, and grows well under various light intensities.^[7] The species growth rate responds to increased dissolved inorganic nitrogen availability, making the species a possible indicator of anthropogenic pollution leading to eutrophication.^[8][9][10]

The thalli of Ulvaria obscura are bladelike, usually less than 5 cm tall and 8 cm thick, consisting of a single cell layer, and typically have between 2 and 6 pyrenoids per cell.^[11] Thalli turn from green to dark brown upon desiccation due to the oxidation of dopamine within the tissues.^[6]

(From Wikipedia, June 9)