KEY CONCEPT Algae are plantlike protists.

Plantlike protists can be single-celled or multicellular. Photosynthetic plantlike protists are called algae. colony daughter colony

Euglenoids are a large group of plantlike protists. mostly photosynthetic some heterotrophic single-celled one or two flagella pellicle nucleus chloroplast eye spot contractile vacuole flagellum Euglena

Dinoflagellates are mostly marine plantlike protists. have two flagella may be bioluminescent have stiff protective plates can cause red tide Dinoflagellates

Diatoms are plantlike protists with glasslike shells. shells made of silica; called tests produce large amounts of oxygen

Multicellular algae are classified by their pigments. Green algae contain chlorophyll a and b. Have cellulose in cell walls Spirogyra

Brown algae contain chlorophyll c. Kelp,seaweeds

Red Algae Red algae contain chlorophyll a and phycoerythrin. Can grow deeper in ocean

Many plantlike protists can reproduce both sexually and asexually. All algae can reproduce asexually. Multicellular algae can fragment. Chlamydomonas divides into zoospores.

Sexual reproduction can be triggered by environmental stress. Some algae produce sexually. Some species alternate generations between asexual and sexual reproduction. May have a haploid life cycle where they spend most of their lives as haploid cells. Sexual reproduction can be triggered by environmental stress.

Part of plankton, food in food webs Make oxygen Food for us Cosmetics Benefits of algae Part of plankton, food in food webs Make oxygen Food for us Cosmetics Biofuels Make agar For bacteria plates For thickening ice cream and other foods sushi