red algae

American  

plural noun

Biology.

singular

red alga

1. marine algae of the phylum Rhodophyta, in which the chlorophyll is masked by a red or purplish pigment.

---

red algae British  

plural noun

1. Also called: red seaweed.  the numerous algae that constitute the phylum Rhodophyta , which contain a red pigment in addition to chlorophyll. The group includes carrageen, dulse, and laver

---

Other Word Forms

• red-algal adjective

Etymology

Origin of red algae

First recorded in 1850–55

Example Sentences

Galdieria extract blue comes from a unicellular red algae, which is an organism that thrives in extreme marine and terrestrial environments, according to the National Institutes of Health.

From Los Angeles Times • May 14, 2025

Kombu hails from kelp and is thicker and more substantial, while nori is derived from red algae.

From Salon • May 14, 2024

Their association with red algae likely dates back 1.5 billion years, the team reports.

From Science Magazine • Apr. 8, 2024

Most are microscopic, single-celled organisms like amoebas, algae, and diatoms, but larger multicellular protists exist -- such as kelp, slime moulds, and red algae.

From Science Daily • Oct. 5, 2023

They gobbled red algae until their bodies turned the color of blood.

From "The House of the Scorpion" by Nancy Farmer