Red Algae

Life cycles Floridian (isomorphic)

1. Polysiphonia type -triphasic

Gametophytes (1n) form a carpagonial branch and spermatangial branch, then the Carpagonial branch developes cystocarps (2n) which break out to form tetrasporophytes that release tetrasporrangia(1n) that become the gametophytes.

2. Bonnemaisonia type - triphasic (polymorphic)

Instead of forming an upright plant brandched filaments at the tetrasporophyte stage are tiny and form a crust on rocks forming an encrusting coraline algae stage

3. Batrachospermum type - Biphasic (polymorphic)

No tetrasporphyte stage, instead has a filament stage with an apicle cell called the Chantransia stage (2n) that goes through somatic meiosis into 1 cell (losing genetic material) that forms a 1n gametophyte thallus on the 2n filaments of the chantransia stage filaments.

4. palmeria type - biphasic (isomorphic)

Same as above but the female gametophyte grows quickly and the male gametophyte grows slowly and does not produce spores until the following generation. The females are always fertilized by the generation before- no sibling fertilization possible.

Evolutionary advantages of no flagella

Reds use alternative life stages to make up for lck of flagella to ensure genetic variation and viability.

Deep/shallow stages

fast /slow growth stages

encrusting/fleshy stages