Algae Notes
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• Scientists use embryological and physical characteristics to show evidence of evolutionary relationships. Today DNA sequencing shows unknown relationships
• Some propose a taxonomic category above kingdom. It would be called Domain or Empire.
Others suggest replacing the old 5 Kingdom system with 6 kingdoms.
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Taxonomic categories from highest to lowest:
Kingdom, Phylum, Class, Order, Family, Genus, Species
• Based on the 6 kingdom system: Animalia, Plantae, Fungi, Protista, Eubacteria and
Archeabacteria (Monera).
Single celled: Protista, Monera, Fungi
Archaebacteria: Ancient forms; Eubacteria: True Bacteria
Homo sapiens ; Homarus americanus
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Autotrophic members of Kingdom Protista
Major “producers” in ocean
Provides basis for food chain; food for most of the world’s water dwelling organisms.
Autotrophic – makes own food
Uses the pigment chlorophyll in photosynthesis
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Photosynthetic activity in algae responsible for 90% of O2 in Atmosphere.
Vary greatly in size and shape(microscopic to kelps 70m); most are found near surface
Found in fresh H2O, marine, moist soils
5 phyla of Algae, based on pigments they contain and how they store food.
• Each has distinctive color due to auxillary pigments. These enhance photosynthesis by capturing other wavelengths of light energy.

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Old Classification used to include “Blue-green algaes” - very primitive (photosynthetic bacteria)
• Blue green Algae is now classified as Cyanobacteria in the Kingdom Monera
1st producers of Atmospheric O2
No longer classified as Algae
Bacillariophyta – new phylum name
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-carotenes, yellow-xanthophyll, brown-fucoxanthins)
Stores food as oils (unpleasant taste in fish that eat these)
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• cell wall made of silica two halves fit together (frustule)
Mostly by binary fission (asexual)
• Found in fresh H2O, and Marine. Very imp. in ocean (found mostly in colder H2O)
• omaceous ooze
(covers much of ocean floor). (Diatomaceous Earth-toothpaste, abrasive filtering agent, and insecticide
Form large portion of marine algae.
Found in warmer waters
Red color from Xanthophyll
Stores food as oils and starches
Bioluminesce when agitated (Luciferin, Luciferinase)
Cont. Pyrrophyta
Example Dinoflagellates:
Unicellular organism with armor-like cell wall
Two flagella

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Reproduce asexually by binary fission
Certain chemical and temp conditions produce an algal bloom of these algae
• Red Tide-bloom of dinoflagellates which release toxins that paralyze and kill fish, shellfish. It is dangerous for humans to eat shellfish during blooms of red tide.
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Found mainly in marine environment
Color brown due to fucoxanthin pigment
Stores food as oil or starch(carbohydrate)
Includes largest algal forms(kelps)
Form extensive underwater forests, forming unique ecosystem
Sometimes har
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Some considered advanced; specialized portions like plants attached to substrate (rock) by Holdfast
Stipe- long hollow tube that ends with a gas-filled ball for buoyancy long leaf-like structures called fronds
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Example: Sargassum
Entire ecosystem adapted to Sargassum; some animals found with sargassum and no where else
• Actually grows in tropical waters; tear loose and carried out to sea where it can grow and multiply.
• Found in open ocean (Sargasso Sea)
• Dominant algae in tropical waters
• Red color due to phycobilin: absorb blue light, allowing these to live in deep water (to 150 meters/~500 ft.
• Rhodophyta store food as starch

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Some in this group called “Coralline Algae,” secrete CaCO3, (like coral) and can become a reef
• Commercially important source of Agar, used as a thickening agent in ice cream. Highest commercial value of all algae! Carrageenan - thickener in baby food and chocolate milk
Very diverse group, many colonial
Chlorophyll dominant-thus color! unlike other alga use same pigments as terrestrial plants
Chlorophyta store food as starch
Terrestrial plants most likely evolved from green algae
Found mostly in Fresh water; some are found near shore (littoral system)
Can impart a distinct green color to water when present; form green slime on boats and pylons
Freshwater Examples: Volvox, Spirogyra
Marine Examples: Ulva “sea lettuce”
Locomotion is amoeba-like
Use pseudopod (false-feet) to move and use as a feeding mechanism
Tests (shells) made of SiO2 (silica)(possibly oldest known animals)
Cytoplasm inside and outside of shell; connected by pores
Some freshwater, most marine
Shells can withstand great pressure

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1. Foraminifera-“Forams”
-Enormous group (20000 sp)
-Most have tests that are multichambered, made of CaCO3 with pores. (Calcareous)
Most marine, creeping (Benthic or Planktonic)
.5 to 100 mm
Ocean bottom above 4000 meters covered with Foram ooze; below 4000 m., tests dissolve
Geologists use fossil forms found in drilling core samples to locate oil.
“Fusulinids”-type of Foram; football shaped
Other Protozoans…
Flagellates –small unicellular that use a flagella for locomotion.