Cyanobacteria, Bacillariophyta & Dinophyta Objective Today we will examine members of the Cyanophyta, Bacillariophyta and Dinophyta. We will become familiar with aspects of their diversity, variation in morphology, and special thallus features. Notebook Requirements (13 drawings) 1) Oscillatoria - draw & label 2) Anabaena - draw & label 3) Nostoc -draw & label 4) Gloeotrichia - draw & label 5) Rivularia- draw & label 6) Stigonema - draw & label 7) Tolypothrix - draw & label 8) Centric diatom-identify 2, draw & label 9) Pennate diatom-identify 2, draw & label 10) Dinoflagellate-identify 2, draw & label Introduction - Cyanbacteria The Cyanobacteria (blue-green algae) are found within the domain Bacteria. Although the exact number of species is debatable, many sources estimate there to be about 4,484 species Cyanobacteria lack membrane bound organelles. However, given that they have chlorophyll A and release oxygen through photosystems I & II, we will consider them to be “algae.” The Cyanobacteria (also called the Cyanophyta) are the oldest organisms to give off oxygen via Photosystems I and II and are estimated to have existed for 3.9 billion years; fossil stromatolites (layered rocks formed by accretion of minerals around cells) date back to the Precambrian period. The Cyanobacteria are ubiquitous, occurring in both seawater and freshwater, on unconsolidated substrata—endolithically in deserts and in Antarctic ice, and epilithically on tropical intertidal limestone. They are important fixers of nitrogen, contribute to toxic red tides, and were some of the first organisms to give off oxygen, thus playing a pivotal role in creating Earth’s oxidizing atmosphere. Many species possess specialized thick-walled cells called heterocysts that aid in nitrogen fixation by separating the site of nitrogen fixation from sources of oxygen. Systematics - Cyanobacteria Order Thallus Characteristics Examples Oscillatoriales filamentous fragmentation, hormogonia production, no specialized cells Oscillatoria, Trichodesmium Nostocales filamentous May have heterocysts, hormogonia and akinetes, may have true or false branching Anabaena, Gloeotrichia Nostoc,Callothrix, Rivularia, Tolypothrix, Cylindrospermum, Stigonema Spirulinales filamentous Spiral filament Spirulina