Algae are categorised into taxonomic groups in the same criteria used for land plants. However, the classification of algae beyond the hierarchy of order had changed dramatically since 1960, when the classification system was developed.
An early morphological study employing electron microscopes revealed variations in traits such as the flagellar apparatus, cell division mechanism, and organelle shape and function, which have been crucial in categorising algae. These diagnostic features of algae have been critical in the taxonomy of algae.
Scientists have recommended significant taxonomic modifications due to similarities and differences across algal, fungal, and protozoan groups and such changes are still being proposed today.
Let us understand the features of algae in this article to get a deeper understanding of its classification.
What are the features of algae?
Algae have various traits that distinguish them from both plants and mammals.
Some algae, for example, can perform photosynthesis like plants. Others might have specialised structures and cell organelles, such as centrioles and flagella, found exclusively in animals. The following section describes some general properties of algae.
- Algae cannot create structures such as roots, stalks, and leaves because they lack a clearly defined body.
- Algae are sunlight-feeding photosynthetic creatures.
- Algae can be found practically everywhere. They just need enough moisture.
- Algae may be unicellular or multicellular in structure.
- Algae can reproduce both asexually and sexually. Asexual reproduction happens via the creation of spores.
- Although algae are self-contained creatures, some of them may create symbiotic relationships with other species.
Types of Algae
Algae comes in many forms. The following are some common types.
- Red Algae
Red algae is a unique species found in both marine and freshwater habitats. It is also known as Rhodophyta. The pigments, phycocyanin and phycoerythrin, are responsible for the algae’s distinctive red colour. Red algae also have chlorophyll d but not chlorophyll b or beta-carotene.Examples-Harveyella , Porphyra ,Gelidium and Gracilaria, Chondrus crispus
- Green Algae
Green algae or chlorophyta is a vast, loosely knit cluster of algae that contains the primary photosynthetic pigments, chlorophyll a and b, and auxiliary pigments like xanthophylls and beta-carotene. Higher species use green algae to perform photosynthesis. Some green algae species have symbiotic relationships with other creatures. The members of green algae are unicellular, multicellular, colonial, and flagellates. Spirogyra, Ulothrix, Volvox, and other well-known green algae are some examples.
3.Brown algae or kelps or Seaweeds or phaeophyta
Brown algae are found in marine water. Brown algae are multicellular filamentous.. Brown algae are the largest in size (up to 60 metre in length). Largest brown algae – Macrocystis. Thallus of brown algae is divided into two parts : lamina-leafy part of photosynthetic part and stipe -elongated tubes called trumpet hyphae are present for food conduction in stipe. to sieve tubes of vascular plants.Due to lamina and stipe brown algae look like leaf (leaf algae).Brown algae have chlorophyll Chl ‘a’ , Chl ‘c’,carotene ,xanthophylls (Mainly fucoxanthin.
The amount of fucoxanthin is more in brown algae due to which this algae is brown in colour (xanthophylls are mostly yellow but fucoxanthin is brown).Example-Postels(Sea palm),Ancyclonema( Ice bloom) ,Sargassum and Laminaria (Kelps)
Note-
Blue-green Algae
As blue-green algae are prokaryotes, they are not categorised as algae as all algae come under eukaryotic organisms. These creatures, also known as cyanobacteria, dwell in damp or watery settings, like other algae. Dams, rivers, reservoirs, streams, lakes, and seas usually contain large colonies of blue-green algae.
Diagnostic features of algae
- According to structure variety and size range
Many algae contain just one cell, whereas the biggest ones have millions. Groups of cells in large, macroscopic algae have specific purposes such as anchoring, transport, photosynthesis, and reproduction; such specialisation shows complexity and evolutionary progress.
- According to distribution and quantity
Algae can be practically found anywhere on the planet and are classified based on their habitats. Planktonic algae are minuscule and grow suspended in water, while neutronic algae grow on the water’s surface and maybe micro or macro-sized.
Environmental and commercial significance of algae
Algae perform photosynthesis to create organic food molecules from carbon dioxide and water by capturing energy from sunlight. Algae, like land plants, are at the bottom of the food chain. Since plants are absent in the seas, nearly all marine life depends on algae, including whales, seals, fishes, turtles, prawns, lobsters, clams, octopuses, sea stars, and worms. As a byproduct of photosynthesis, algae produce oxygen in addition to organic molecules. Algae generate 30 to 50 per cent of the net global atmospheric oxygen, necessary for the respiration of humans and other terrestrial animals.
Crude oil and natural gases are the remains of ancient algae’s photosynthetic byproducts, transformed by microorganisms. The North Sea oil deposits are said to have developed from coccolithophore algae (family Prymnesiophyceae). The Colorado oil shales could have been formed from algae related to Botryococcus (green algae).
Conclusion
Algae are eukaryotic creatures that lack roots, stalks, and leaves but contain chlorophyll and other pigments that allow them to perform photosynthesis. According to some experts, algae create half of our planet’s oxygen. They are also a source of crude oil. These algae biofuels have the potential to replace fossil fuels. Algae also serve an essential role in stabilising atmospheric carbon dioxide and serve as efficient carbon sinks. Some algae are also used in the preparation of food. Agar, which is used to make ice cream and jellies, is derived from Gelidium and Gracilaria.