Algae By Erica Gonzales

What are algae? Protists that use photosynthesis Classified by their pigments: Purple, Rusty-red, Olive-brown, Yellow, Golden Brown Both unicellular and multicellular

Characteristics Phytoplankton Unicellular Algae Multicellular Algae Phytoplankton Major producer of nutrients and oxygen in the world Classified into 3 phyla: Euglenoids Diatoms Dinoflagellates Look like plants No roots, stem or leaves Large and Green

Unicellular Algae Euglenoids Diatoms Dinoflagellates

Euglenoids Unicellular aquatic protists Plant AND animal characteristics Made of cellulose; no cell wall Have flagella to move towards light or food Have a flexible pellicle around cell membrane

Parts of a Euglenoid Notice that there are similarities between the Euglenoid and a plant cell

Characteristics Plant-Like Animal-Like Contain chlorophyll Conduct photosynthesis Autotrophic Can eat food when light is not available Ingest food like protozoa Heterotrophic

Diatoms Unicellular photosynthetic organisms Have shells composed of silica Abundant in fresh and saltwater ecosystems Box-shaped Contain chlorophyll and carotenoids (a pigment) for golden color

Diatom Shells Each species of diatoms has its own unique shape, differently patterned with grooves and pores.

Food Use sunlight for food (photosynthesis) Food is stored as oils, not starch Gives them an oily taste to fish that eat them Oil allows them to float near water’s surface for sunlight

Reproduction Asexually Sexually Two halves of the box split Each pieces produces a bottom half to fit inside it Half of offspring are smaller than parents Stops when diatoms are ¼ original size Then switches to sexual reproduction Produce gametes (egg or sperm) Fuse to form zygotes Zygote fully develops and divides asexually for a while

Diatom Reproduction

Death Shells sink to ocean floor at death Million-year-old diatom deposits have been found Used for tooth or metal polishes

Dinoflagellates Have cell walls made of thick cellulose plates Contain chlorophyll, carotenoids & red pigments 2 flagella in grooves right angles to each other Live in freshwater, but mostly saltwater Can live symbiotically with jellyfish, mollusks and coral Some species emit light

Toxic Dinoflagellates Several species produce toxins One species Pfiesteria piscicida can cause massive fish kills Gonyaulax catanella produces extremely lethal nerve toxins A very numerous population of these cause a red tide Inhabited by 40 to 60 million dinoflagellates per liter of seawater Can make humans ill

Red Tides The yellow and orange spots in the water are red tides, areas so densely infested by toxic dino- flagellates.

Multicellular Algae Red Algae Brown Algae Green Algae

Red Algae Multicellular marine seaweeds Thallus – body of a seaweed: lacks roots, stem and leaves Uses structure called holdfasts to attach to rocks Found in tropical waters or in cold waters on rocky coastlines

Pigments Contain Chlorophyll and phycobilins – photosynthetic pigments that absorb green, violet, and blue light (the only lights that penetrate water past 100 meters) Allows algae to deeper than most seaweeds

Brown Algae Live in salt water along rocky coasts in cooler areas Contain chlorophyll and fucoxanthin Fucoxanthin – yellowish-brown carotenoid (a pigment) that gives them their brown color Most species have air bladders Keep them floating near the surface for sunlight

Kelp Largest and most complex brown algae Thallus (body) is divided into holdfast, stripe and blade Holdfasts anchor them to rocks or ocean floor May grow to 60 meters long Some giant kelps form underwater forests Many organisms live in them

Green Algae Most diverse algae; over 7000 species Have many pigments that give yellow-green color Main one is chlorophyll Live in: freshwater, saltwater, moist soil, tree trunks, even the fur of sloths

Different Types of Green Algae Colonies Multicellular Unicellular Different Types of Green Algae Colony: group of cells that lives together in close association

Volvox Colony Composed of hundreds of cells with flagella in one layer to form a hollow ball Cells are connected by strands of cytoplasm Flagella face outwards and beat in unison to spin the colony in the water Smaller balls, “daughter colonies” form inside the hollow space Wall of larger colony eventually breaks to release the daughter colonies

Reproduction Reproduce sexually AND asexually Fragmentation – (asexual reproduction) an individual breaks up into pieces and each piece grows into a new individual Some species use this method of asexual reproduction Alternate from producing sexually and asexually throughout lifecycle Produce gametes for sexual reproduction Produce spores for asexual reproduction

Alternation of Generations Pattern of alternating between existing as a haploid and diploid organism, creating 2 different generations Gametophyte – haploid form of organism; produces gametes They fuse to form a zygote Sporophyte – diploid form of organism, also zygote of previous generation; produces spores Cells undergo meiosis and eventually become haploid spores that can become gametophyte

Life Cycle of Green Algae Throughout their lives, green algae switch from being a diploid to a haploid.