Phyla of Algae

General Botany Lab

Chlorophyta:

Green Algae

Chlorophyta Pigments:

Chlorophyl a, b

Chlorophyta Energy Storage:

Starch

Chlorophyta Cell Wall:

Made of cellulose

Chlorophyta Reproduction Types:

Isogamy

Anisogamy

Oogamy

Isogamy:

Morphologically identical gametes

Anisogamy:

Size differentiation; sperm smaller, both motile

Oogamy:

Egg non-motile, sperm flagellated

What are some examples of Chlorophyta?

Chlamydomonas

Volvox

Spirogyra

Oedogonium

Chlamydomonas:

Unicellular, biflagellated (apical)

Cup-shaped chloroplast with pyrenoid body

Stigma acts as a light detector

Volvox:

Colonial organism with cells connected by cytoplasmic bridges

Contains vegetative and reproductive cells

Life Cycle: Sperm from gonidia fertilizes egg in oogonia → Zygote → Meiosis → Haploid cells → New colony

Spirogyra:

Filamentous; spiral-shaped chloroplasts

Sexual reproduction through conjugation tube

Life Cycle: Zygote → Dormant zygospore → Meiosis → Haploid spores → Mitosis → New filaments

Oedogonium:

Filamentous, oogamous reproduction

Oogonium produces eggs; antheridium produces sperm

Fertilization results in a young zygote attached to the filament

Rhodophyta:

Red Algae

Rhodophyta Pigments:

Chlorophyll a, c, phycobilins (allow light capture in deep water)

Rhodophyta Energy Storage:

Floridean starch (branched glucose polymer)

Rhodophyta Cell Wall Components:

Cellulose

Sulfated Galactans (agar, carrageenan)

Rhodophyta Applications:

Agar (used in lab cultures and food) from Gelidium and Gracilaria

Carrageenan (thicker in foods and cosmetics) from Chondrus crispus

Some with calcium carbonate

Rhodophyta Examples:

Gelidium and Gracilaria (agar producers)

Coralline algae with hard, calcified walls

Phaeophyta:

Brown Algae

Phaeophyta Pigments:

Chlorophyll a, c, fucoxanthin

Phaeophyta Energy Storage:

Laminarin and Mannitol

Phaeophyta Structure:

Multicellular with specialized parts

Phaeophyta Specialized Parts:

Holdfast

Stipe

Blade

Pneumatocysts

Holdfast:

Anchors algae

Stipe:

Stem-like structure

Blade:

Photosynthetic surface

Pneumatocysts:

Air bladders for buoyancy (Macrosystis)

Phaeophyta Reproduction:

Oogonia and antheridia located in conceptacles on receptacles

Phaeophyta Examples:

Sargassum, Macrocystis, Fucus

Chrysophyta:

Diatoms

Chrysophyta Pigments:

Chlorophyll a, c, fucoxanthin

Chrysophyta Structure:

Diploid life cycle

Silica-based frustules

Storage Product: Laminarin

Two morphologies:

Centric

Pennate

Chrysophyta Locomotion:

Mucus secretion through raphe

Pyrrhophyta:

Dinoflagellates

Pyrrhophyta Pigments:

Chlorophyll, a, c, peridinin

Pyrrhophyta Structure:

Unicellular, bi-flagellated

Cellulosic plates

Pyrrhophyta Ecological Role:

Responsible for harmful algal blooms (red tides)

Release toxins (accumulation in shellfish)

Algae Life Cycles:

Monobionic

Dibionic

Monobionic:

Gametophyte and sporophyte phases indistinguishable

Dibionic:

Alternation of generations with morphologically distinct gametophytes and sporophytes

Ulva (sea lettuce) Life Cycle:

Haploid gametophyte and diploid sporophyte stages alternate

Gametes fuse to form a zygote → Diploid sporophyte → Meiosis → Haploid gametes