Algae: Types and Characteristics

Study Notes

Dinoflagellates:
- Have two flagella for spinning through water.
- Covered with cellulose plates.
- Primarily live in saltwater habitats.
- Responsible for "red tides".
Diatoms:
- Lack cilia and flagella.
- Have glasslike cell walls containing silica.
- Exhibit a variety of shapes and patterns.
- Rigid cell walls have pores for gas and material exchange.
- Most abundant organisms in the ocean.
- Used as abrasives in polishing agents, detergents, and toothpastes.

Once classified as plants due to chloroplasts and photosynthesis.
Classified as protists because of different reproductive structures from plants.
Not necessarily microscopic.
Green Algae (Chlorophyta):
- Most live in freshwater, some in the ocean.
- Grow as filaments or flat leaf-like cells.
- Examples:
  - Chlamydomonas: Found in ponds and moist soil, has retractable flagella.
  - Volvox: Common colonial green algae, lives in ball-shaped colonies.
- Some form symbiotic relationships with fungi, resulting in lichens.
Red Algae (Rhodophyta):
- Grow in warm, saltwater habitats.
- Can be orange, green, brown, and black.
- Photosynthesize at great depths due to pigments other than chlorophyll.
- Important for coral reefs.
Brown Algae (Phaeophyta):
- Grow in cool, saltwater habitats.
- Examples: Kelp
- Have root-like structures for anchoring and specialized air bladders for buoyancy.
Algae are a significant component of plankton, specifically phytoplankton, due to their photosynthetic abilities.

Divided into three groups:
- Plasmodial slime molds
- Cellular slime molds
- Water molds
Decomposers that recycle organic material back into the environment.
Extract nutrients from dead organic matter.

Appear slimy or wet.
Have various colors.
Different forms through their life cycle:
- Plasmodium: Feeding stage, forming a mass of amoeba-like cytoplasm, feeding on bacteria and small organisms.
- Spores: When conditions are unfavorable, the mold stops feeding and forms a spore-producing body. Spores are released when conditions improve and develop into plasmodium again.

Include white rusts and downy mildews.
Decomposers or parasites.
Typically grow in freshwater on decaying plants and animals.
Not true fungi because:
- Cell walls contain cellulose, not chitin.
- Spores have flagella, unlike true fungi spores.
Water mold caused the Irish Potato Famine.