The ancestors of the reds, greens, and chromists were all unicellular. Each group developed multicellularity independently of the others. Cellular division 2. Cellular cohesion C. Multicellularity in algae. 1. colony - loose association of few to 1,000 of cells 2.
Some cells remain meristematic - retain ability to divide.
Over 4000 species 2. Principal seaweeds of tropical marine waters 3. Gracilaria - source of agar for culturing 3. Gelidium - source of alginates for chocolate syrup, mayonnaise 4. A. Distinguishing traits 1.