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, Oscillatoria, no specialized cells Trichodesmium Nostocales filamentous May have heterocysts, hormogonia and Anabaena, Gloeotrichia akinetes, may have true or false Nostoc,Callothrix, branching Rivularia, Tolypothrix, Cylindrospermum, Stigonema Spirulinales filamentous Spiral filament Spirulina

Draw and label each specimen. Note the overall thallus morphology and any specialized cells. Please make sure you label the Filament, Trichome, Mucilaginous Sheath, Heterocyst, and Akinete) (if applicable).

Cyanobacteria- prepared specimans Order Oscillatoriales- Oscillatoria - Planktonic, hormogonia, freshwater Q: What are hormogonia? Q: How does Oscillatoria fix nitrogen without having specialized cells? Order Nostocales Anabaena - Planktonic, Produces neurotoxins that become release when they are ingested by animals, akinetes & heterocysts visable, negative phototaxis—can steer the tip of the filament towards light. Q: What is the purpose of heterocysts? Q: What is the purpose of gas and starch vacuoles? How can these vacuoles affect movement in CyanoBacteria? Nostoc- Often associated with fungi in lichens, filamentous, can form colonies, akinetes & heterocysts visable Q: How can you distinguish between Anabaena & Nostoc? Compare and contrast their structure. Gloeotrichia –akinates and heterocysts visable at tip Q: What are akinetes? Rivularia- draw & label Q: How can you distinguish Gloeotrichia from Rivularia? Compare and contrast their structure. Stigonema - Inhabits moist rocks and soil, often associated with fungi in lichens, filaments can be multiple cells in width (multiseriate) Q: What type of branching does Stigonema exhibit? Tolypothrix- Planktonic, often in freshwater lakes Q: What type of branching does Tolypothrix exhibit?

Bacillariophyta & Dinophyta- live specimans Identify, observe, draw and label: 2 Pennate diatom & 2 Centric diatom- label Raphe, Frustule, Girdle, Epithecum, Hypothecum Q: What type of life history do diatoms exhibit? Q: How do diatoms move? Q: Why do some diatoms form chains? Q: What are diatoms made of?

2 Dinoflagellate- label Epicone, Hypocone, Undulipodium (Transverse & Longitudinal) Q: What type of life history do dinoflagellates exhibit? Q: How do dinoflagellates move? Q: What is the purpose of spines? Q: What are dinoflagellates made of? Order Oscillatoriales

Order Nostocales

Anabaena spp

Akinete Heterocyst

Heterocyst Akinete

Gloeotrichia spp Nostoc spp

Rivularia spp.

Stigonema spp.- true branching

Tolypothrix- false branching, often occurs at