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What is an Algae?
Algae are referred to as non-green plant-like organisms that are autotrophic, simple, and chlorophyll-bearing and are mostly aquatic but can be found in moist stones, woods, and also in association with animals and fungi (lichens). They are generally microscopic but some are massive in appearance e.g. giant kelps.
How Algae is reproduced?
a) Algae reproduce by three methods namely sexual, asexual, and vegetative reproduction
b) Vegetative reproduction occurs as a result of thallus development from a small fragment this process is known as fragmentation.
c) Asexual reproduction is done by developing various kinds of spores. Most common being the zoospores (flagellated)
d) Sexual reproduction results from the fusion of two gametes. It can be of three types
e) Isogamous - Gametes are similar in size. It can either be flagellated (Chlamydomonas) or Non-Flagellated (Spirogyra)
f) Anisogamous - Gametes are dissimilar in size
g) Oogamous - Male gamete is small and motile while female gamete is large and non-motile e.g. volvox
What are the uses of Algae?
1. Helps in carbon dioxide fixation by photosynthesis
2. Helps to circulate energy-rich food in the food cycles of aquatic animals.
3. Agar is obtained from some species of Gracilaria.
4. Spirulina is used as a food supplement as it is rich in proteins.
What are the three classes of Algae?
They are known as green algae due to the presence of chlorophyll a and b. The chloroplast is found in different shapes like spiral, cup-shaped, reticulate, etc. Chloroplast contains a storage body known as pyrenoids having proteins and starch. Their cell wall is rigid having cellulose on the inner side and pectose on the outer wall. Reproduction is reported to occur through vegetative, asexual, and sexual reproduction. Some members include Chlamydomonas
What is the Class Phaeophyceae?
Commonly found in marine systems and is also known as brown algae. They are known to occur in simple filamentous forms like Ectocarpous and massive forms like kelps. They generally have pigments like chlorophyll a and c, xanthophylls, and carotenoids. The color of brown algae depends on the amount of fucoxanthin (xanthophyll) pigment present in them. Food storage generally occurs in the form of mannitol. The cell wall is covered by algin from outside. It also possesses a holdfast having the stalk, stipe, and front to attach to the substratum. All three type of reproduction is seen in brown algae. Pear-shaped unequal biflagellated zoospores are seen in the case of asexual reproduction. Some members include Ectocarpus, Dictyota, Laminaria, Sargassum
What is Rhodophyceae?
This alga is red in color because of the presence of red pigment r-phycoerythrin. They are mostly marine and prefer warmer regions. They possess a complex body with food stored in the form of Floridean starch. They reproduce by all three means with the help of non-motile spores in case of asexual reproduction and non-motile gametes in case of sexual reproduction. Some members include Polysiphonia(Fig 5), Porphyra (Fig 6), Gracilaria and Gelidium, etc.