Ectocarpus

(Phaeophyta)

Ectocarpus mostly grow in marine habitats. They play an important role in maintaining the marine environment ecosystem because they are the source of food for marine life. It is a brown alga because a pigment named fucoxanthin is present in it which masks the characteristics of the green color of chlorophyll and shows a brownish appearance in marine water. It mostly grows on rock surfaces.

Algal body of Ectocarpus:

The algal body is filamentous and heterotrichous which is differentiated into prostrate and erect systems.

The prostrate system is profusely branched and attached to the substratum. So, it provides support by anchoring with substratum to the ectocarpus.
The erect system develops from the prostrate system which remains free-floating. It is much-branched and well-developed. This region can perform photosynthesis and is also involved in the reproduction process. The photosynthetic pigments are chlorophyll a, c, β-carotene, and fucoxanthin.

Cell structure of Ectocarpus:

The cells are rectangular or cylindrical.
The outer layer of the cell wall of the ectocarpus is called the pectic region while the inner side is made up of cellulosic layers.
The cell wall has a gelatinous appearance because it is composed of algin and fucoidan.
inside the cell wall, the cell membrane is present. Cell membrane covers the whole cell's organelles, and cytoplasm and is elastic in nature.
The protoplast contains one central nucleus many chromatophores and many vacuoles.

Reproduction:

Ectocarpus can be reproduced both sexually and asexually.

Asexual reproduction:

The asexual mode of reproduction takes place by zoospores. The diploid algae (2n) produces two types of sporangia:

Unilocular sporangia (develops haploid spores)
Neutral sporangia (develop diploid spores)

The haploid spores on germination develop gametophytic algae.
The gametophytic algae bear plurilocular gametangia.
The plurilocular gamentangia produces gametes.
The gametes produced by plurilocular gametangia then form diploid spores after fertilization.
These diploid spores then produce gametes which are haploid by the process of meiosis.
In this way, alternation of generation occurs and it completes the life cycle of Ectocarpus.

Sexual reproduction:

Two types of sexual reproduction occur in Ectocarpus:

Isogamous mode of reproduction
Anisogamous mode of reproduction

The gametes are produced inside the gametangia, which are developed in haploid plants.
The unilocular gametangia produce haploid gametes.
While the Pleurilocular sporangia produce diploid zoospores.
During fertilization, many male gametes come closer to the female gamete.
The male gametes are captured by the female gamete (large interior flagellum).
This stage is called clump formation.
Out of many, only one male gamete succeeded in fusing with the female gamete.
All remaining male gametes are then gradually destroyed because there is no need for them.
The mate gamete that fuses with the female gamete then forms the zygote.
The zygote undergoes germination without any reduction division.
On germination, it develops into a sporophytic algae which is diploid in nature.
The sporophytic algae again develop unilocular and plurilocular sporangia and in this way the life cycle of Ectocarpus continuous itself.