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Understanding Algae: Diversity, Structure, and Importance in Ecosystems

Algae are not merely green scum or seaweed; they are a diverse group of photosynthetic organisms found in various aquatic environments. This study of algae, or phycology, reveals their key role as primary producers in oceans, contributing significantly to oxygen production. Algae come in multiple forms—green, brown, and red—each with unique structural characteristics and reproductive methods. This overview explores their classification, body plans, reproduction types, and the ecological significance of various algal phyla, emphasizing their importance in aquatic ecosystems and human uses.

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Understanding Algae: Diversity, Structure, and Importance in Ecosystems

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Presentation Transcript

  1. Kingdom PlantaeA look at the Algae...

  2. Algae • Confusing name…it is not just green scum on ponds nor just seaweed…many different groups that are not related to one another. • Phycology is the study of algae • simple in structure but very common and very successful • most live in water attached to rocks or free floating • use sunlight for photosynthesis (chlorophylls a and b….just like true plants!) • main food producers in the oceans • important suppliers of oxygen

  3. Body plan of Algae... Blade (fronds) Laminaria (kelp) Stipe The plant body of an alga is called the thallus (pl. thalli) Holdfast

  4. Laminaria holdfast

  5. Classification of algae... • Color (for years!) • Type of storage product (food) • Thallus (size & structure) • Reproduction

  6. Sexual gametes unite to form a zygote (sperm/egg) Isogametes if same size & shape Heterogametes if not same size/shape (female gametes large & unable to move) Asexual No gametes (no union of cells) Mitosis (unicellular cell may divide into two new cells) Zoospores (reproductive cells with 2 flagella)..each zoospore can develop into a plant Reproduction of Algae

  7. Phylum Chlorophyta (green algae) • Most abundant & widely distributed of all algae • unicellular & multicellular • approx. 6000 species • contain cholorphylls (like higher plants) • store starch in their cells (like higher plants) • Believed higher plants evolved from green algae.

  8. Phylum Phaeophyta (brown algae) Many species grow in cool waters along rocky coasts (anchored to rocks by their root-like parts & gas-filled structures that function as floats ). Brown algae are an important source of iodine. Can be used as fertilizer or as food for humans. Other species are a source of algin, which is used to thicken ice crème and other foods.

  9. Multicellular but never as large as the largest brown algae More complex that other forms of algae Most live in salt water but in warmer waters and greater depths Very beautiful colors (red, green, yellow, purple), feathery Cell walls contain cellulose as well as other substances like agar (thickener in foods like ice crème, puddings, and cake icing; medium on which bacteriaand fungi are grown in laboratories) Carrageenan is another product of red algae which is a type of stabilizing agent used to prevent separation of food mixtures (i.e. chocolate and milk) Phylum Rhodophyta (red algae)

  10. What characteristics of algae have we learned?

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