Life cycle of Ectocarpus siliculosus. Both Ectocarpus sexual and asexual life cycles are displayed. Gametes (right side) released from WT male gametophytes . The life history of Ectocarpus fasciculatus var. refractus (Kiitz.) Ardis. from Roscoff , France, has been studied in culture. This species proved to be the sporophytic. the sexual pheromones and infection of Ectocarpus by viruses. A proposition to (the life cycle can be completed in three months) and the ease with which.
|Published (Last):||18 October 2017|
|PDF File Size:||14.28 Mb|
|ePub File Size:||19.71 Mb|
|Price:||Free* [*Free Regsitration Required]|
In this clump formation Fig. The alga has an isomorphic, alternation of generations, the gametophyte and the spoiophvte being essentially alike in appearance. The diploid plants bear both unilocular and plurilocular sporangia. Features and Distribution Algae. The zoospores formed from plurilocular sporangia are alike with the zoospores i. The neutral sporangia produce diploid swarmers which germinate to form sporophytes.
The unilocular sporangia develop singly on tips of small branchlets. The gametes are produced inside the plurilocular gametangia, developed on haploid plants. This cell functions as sporangial initial Fig. Zoomeiospores on germination develop ectocapus plants.
The zoospores remain motile for hours and then germinate into diploid thallus which later on bears unilocular and plurilocular sporangia. Its diploid nucleus divides mitotically to make diploid Ectocarpus plant. Ectocarpus is found attached on sea rocks. The isogametes or anisogametes fuse to form diploid zygospore.
Some species of Ectocarpus are epiphytic e. Occurrence of Ectocarpus 2. The physodes contain polyphenols, probably function as lysosomes. In a limited number of species growth is trichothallic, during which intercalary meristems are found at the base of the hairs. Discovery, Classification and Structure. The protoplast of each compartment is metamorphosed into a single biflagellate zoospore.
Ectocarpus: Occurrence, Features and Reproduction
Apical growth is rather rare in the erect threads. It repeatedly undergoes transverse divisions to form a row of cells Fig. The zoospores remain inactive for seconds then become free and swim in water. After sometime one male gamete fuses egg to make zygospore and other gametes detach themselves from female gamete. Answer Now and help others. The largest mega-gametangia represent oogonia and the smallest micro-gametangia represent antheridia Fig. This multicellular structure is called plurilocular sporangium.
The diploid nucleus of the initial first undergoes meiosis followed by several mitotic divisions, thus hapioid nuclei are formed. The plurilocular gametangia and plurilocular sporangia are similar in structure and development. The asexual reproduction takes places with the help of biflagellate zoospores. Answer Now and help others.
This results in formation of haploid nuclei Fig. Each mature cucle sporangium consists of vertical rows of many small cubical cells or compartments. The active male gametes cluster around female gamete and cling themselves by their anterior flagellum.
The ultimate branch-lets of the erect portion are generally attenuated to an acute point Fig. In other species of Ectocarpus gametes from same plant can fuse to form a zygote showing isogamous reproduction. This stage is called cyclf formation Fig. The two gametes of same gametangium or from two different gametangium of same thallus fuse to from zygospore.
The plurilocular gametangia develop singly from the terminal cell of the lateral branchlets.
The nature of growth varies with the region of plant body and also with species. The more active gametes are considered male. The female gamete after liberation secretes a volatile sexual attractant sirenine.
Quick Notes on Ectocarpus (With Diagram) | Algae
The haploid plants bear plurilocular gametangia. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Further divisions are transverse and vertical in these ectocarphs to make hundreds of cubical cells arranged in transverse layers. Out of many, only one male gamete fuses with the female gamete Fig.