Characteristics of Algae:
- Eukariotic (endosymbiotic origin)
- Aquatic (fresh water and salt water)
- Photosynthetic autotrophs (Chlorophyll a + various
photosynthetic accessory pigments).
- Cell walls (various components that can be useful for
classifying different groups).
Life as an aquatic photosynthetic autotroph:
- Source of energy?
- Depth in water column affects: light availability (no light
below 300 m depth) and spectral composition (red wavelengths
strongly absorbed by water)
- Assimilation of dissolved inorganic molecules of carbon and
- Supported by water.
Diversity and importance:
- Microalgae - phytoplankton
- Macroalgae - seaweeds - body (thallus) plan: holdfast, stipe,
Sexual life histories are quite varied even within major taxonomic
Distinguish between major groups in terms of body plan, habitat,
accessory pigments, cell wall composition and importance to humans.
- Brown algae (Phaeophyta)
- Red algae (Rhodophyta)
- Green algae (Chlorophyta)