Types of Algae – Class 11 | Chapter – 3 | Short Notes Series PDF

Types of Algae: Algae are divided into primary groupings based on their photosynthetic colors, which include green algae, red algae, brown algae, and golden algae. Others do not regard blue-green algae (Cyanophyta) to be algae, but rather group them alongside bacteria in the Kingdom Monera.

Types of Algae

i) Green Algae

Any photosynthetic algae that contain the pigments Chlorophyll A and Chlorophyll B is referred to as green algae. Food is stored in plastids as starch. They come in a variety of forms, including unicellular (e.g. Micrasterias sp.), multicellular (e.g. Micrasterias sp.), and colonial (e.g. Micrasterias sp.). Those that seem filamentous or generate leaf-like thallus are multicellular types, e.g., Ulva and Volvox that form colonies. Charophytes (usually found in freshwater settings) and Chlorophytes are two types of green algae. Mostly marine, Green algae may also be found in terrestrial environments, e.g. soil, rocks and trees. On land, several green algae species have been discovered to develop symbiosis. For example, Chlorella species develops a symbiotic relationship with Hydra sp.

ii) Red Algae

Rhodophyta is the phylum that includes red algae. Apart from chlorophyll, they are recognized by their red tint, which is attributed to the incidence of accomplice pigments in phycobillisomes such as Phycoerythrin, Phycocyanin, and Allophycocyanins. Examples of red algae include Rhodella, Compsopogon, Stylonema, Bangia, Porphyra, Porphyridium cruentum, Hildenbrandia, Nemalion, Corallina officinalis, Ahnfeltia, Gelidium, and others.

iii) Euglenophyta

Euglena is a protist that lives in both fresh and saltwater. Plant cells, like some euglenoids, are autotrophic. They have chloroplasts and are capable of photosynthesis. They have a protein-rich covering called the ‘pellicle’ that shields them instead of a cell wall. Other euglenoids, like animal cells, are heterotrophic, meaning they feed on carbon-rich substances found in the water and unicellular creatures. With the right organic material, certain euglenoids can survive in the dark for a while. The eyespot, flagella, and organelles are all features of photosynthetic euglenoids (nucleus, chloroplasts, and vacuole).

IV) Chrysophyta (Golden-Brown Algae and Diatoms)

The most common forms of unicellular algae are golden-brown algae and diatoms, which account for over 100,000 distinct species. Both may be found in both fresh and salt water. Diatoms are a form of plankton found in the water that is far more prevalent than golden-brown algae. Diatoms have a ‘frustule’, which is a silica shell that varies in shape and structure according to the species. The productivity of golden-brown algae in the ocean is comparable to that of diatoms, despite their smaller numbers. Because their cells are under 50 micrometers in diameter, they’re called nanoplankton.

V) Pyrrophyta (Fire Algae)

Fire algae are unicellular algae that employ flagella for movement and are often found in seas and certain fresh water sources. Dinoflagellates and cryptomonads are the two classes of pyrrophyta. Dinoflagellates can generate a red tide, which causes the water to become red owing to their abundance. Other Pyrrophyta species, like some fungi, are bioluminescent. They give the impression that the water is on fire at night. Dinoflagellates are also dangerous because they create a neurotoxin that may cause muscle damage in humans and other animals. Cryptomonads, like dinoflagellates, may cause harmful algal blooms that color the water ‘red’ or ‘dark brown’.

VI) Paeophyta (Brown Algae)

Brown algae are the biggest algal species, consisting of seaweed and kelp variants found in marine habitats. These creatures have an ‘anchoring organ’, ‘air pockets’ for buoyancy, a stalk, ‘photosynthetic organs’, and ‘reproductive tissues’ that produce spores and gametes. These protists have an alternation of generations throughout their life cycle. Sargassum weed, rockweed, and gigantic kelp, which may grow to be 100 meters long, are examples of brown algae.

VII) Xanthophyta (Yellow-Green Algae)

The number of species of yellow-green algae is the smallest, ranging from 450 to 650. They are single-celled creatures having cellulose and silica cell walls and one or two flagella for movement. Their chloroplasts are devoid of a pigment, making them seem lighter in hue. They grow in tiny colonies with only a few cells. Yellow-green algae are most commonly seen in freshwater, although they may also be found in saline water and damp soil.


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By Team Learning Mantras