Phaeophyta - Brown Algae-8 

Sexual Reproduction

Both gametes are usually Motile.
Gametes can be Identical
(Isogamy).
Gametes may look similar but one is larger than the other (Anisogamy).
Sperm are Motile & the Egg is large & Nonmotile
(Oogamy).

Fertilization usually occurs Outside the Gametophytes.

Eggs & Sperm can be formed in a Gametangium.

Gametangia can be subdivided into many single cells each of which produces one gamete. The latter are called
Plurilocular (Many Chambers) Gametangia.
Plurilocular Gametangia occur on Gametophytes and Sporophytes.

Male and Female Gametophytes may be morphologiclly Identical (Isomorphic) or distinct (Heteromorphic).

Sporophytes and Gametophytes can look similar (Isomorphic) or they may be morphologically distinct (Heteromorphic).

Ectocarpus Life Cycle

Isomorphic Haploid Gametophyes produce Male or Female Plurilocular Gametangia.

Motile Isogametes are produced.

The Female Gamete retracts its flagella and settles on the substrate.
It releaes a powerful pheromone which attracts Sperm.

Males remain motile for 24 hrs.

Sperm attach to the Egg with one of its flagella.

The flagella retract and the Sperm fuses with the Egg (Syngamy/Fertilization).

The Zygote divides to produce the Sporophyte Generation.

The sporophyte produces Plurilocular MITOsporangia which produce Diploid Spores. This is a form of ASEXUAL reproduction.

Meiosis occurs in UNILocular Meiosporangia to produce Meiospores.

The Meiospores produce Male or Female Gametophytes.