“Plant-Like” Protists: Multicellular Algae

Multicellular Algae AKA “Seaweed” Algae lack an internal system of tubes to move water and material from one part of the plant to another Seaweeds are large, multicellular marine algae, grow on or near rocky shores, are most closely related to unicellular algae, and are often edible.

Multicellular Algae – Green, Red, and Brown Algae Most are multicellular Can reach 60 meters in length, cells contain cell walls, contain chlorophyll a Seaweeds are classified into three different groups, based partly on the types of pigments present in their chloroplasts: green algae, red algae, and brown algae (including kelp).

Phylum Chlorophyta – Green Algae Chlorophyll a and b Store food as starch, found in moist areas and fresh water Some marine Some live as single cells, some form colonies, and some are multicellular Sexual and asexual reproduction May be ancestor to land plants Vulvox (colonial algae), spirogyra, ulva

Green Algae Examples Vulvox Ulva Spirogyra

Phylum Rhodophyta – Red Algae Contain chlorophyll a and reddish accessory pigments called phycobilins – good for absorbing blue light and can live deeper than other algae Store food as special starches Found from far North to the tropics to a depth of 170 meters Chondrus crispus, Irish moss – common red algae

Red Algae Examples Chondrus crispus Antithamnion plumula

Phylum Phaeophyta – Brown Algae Chlorophyll a and c as well as brown pigment called fucoxanthin Store food as special starches and oils Important marine algae found in shallow temperate regions Largest, and most complex of the algae Kelp, sargassum, fucus

Fucus Anatomy

Brown Algae Examples Fucus Kelp

Reproduction in Algae Alternation of generations – alternate generations are sexual and asexual – sexual reproduction involves the production of gametes and asexual production involves haploid cells called zoospores (switch back and forth)

Reproduction in Ulva – a Green Algae Diploid algae called the sporophyte, haploid algae called gametophyte Two different gametophytes – male and female – having two types of gametophytes is called heterogamy

Ulva Life Cycle MITOSIS MEIOSIS Zygote Gametes fuse Sporophyte Spores FERTILIZATION Gametes Female gametophyte MITOSIS Diploid Haploid Male gametophyte

Reproduction in Fucus – a Brown Algae Alternation of generations and heterogamy Female gamete – egg Male gamete - sperm

Human Uses of Algae Drugs Sushi Ice cream Salad dressing Pudding Candy bars Eggnog Toothpaste Deoderant Agar……..