Types of Algae: Its General Characteristic and Importance
Algae are a diverse group of simple and plant-like organism. Most algae use the energy coming from the sunlight to produce their own food through the process of photosynthesis. But not like other plants, algae lack the roots, leaves and other physical structure of a true plant. Algae are the most significant photosynthesizing organism in the biosphere as they capture more of the sun’s energy and produce more oxygen that other plants.
Algae support abundant animals as they create most of the foundation in aquatic food webs. They have varied sizes and grow in different habitats. Seaweeds are the largest forms of algae as they can stretch as much as 300 feet from the ocean floor to the water’s surface. Algae also grows on the ground, porous rocks, in trees and even in animals. Since algae can grow in diverse habitats they can tolerate a wide range of temperature. Some algae can thrive on snow banks, in a hot springor even in deep polar ice.
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Algae live in symbiosis relationship with other organism. Like for example:
- Algae live with fungi to form lichen
- Zooxanthellae, a type of algae that lives inside the cells of reef-building coral. They provide oxygen and nutrients to the reef and at the same time serves as protection and simple nutrients to algae.
Algae were one of the earliest life-forms that can produce oxygen via photosynthesis. They are also considered as “photosynthesizers” for billions of years because they still thrive at present.
Algae is considered eukaryotic, a photosynthetic protist whose cells contains a nucleus that encloses the cell’s hereditary materials. They are classified into smaller group, according to the dominant pigment they produce:
- Green Algae
- Brown Algae
- Red algae
Types of Aquatic Plants and Algae
Do algae harm us in any way?
Green Algae belongs to the largest phylum of the algae, which is about 6000 to 7000 species which is Phylum Chlorophycophyta. The name was derived from the Greek word “Chloros” which means “green” and “Phykos” which means “seaweeds”. They have a common name “Grass-Green Algae” because of its bright green color with two types of chlorophyll A and B.
The earliest green algae that have appeared in the fossil record were more than two billion years ago. Green algae are abundant in damp soil, land plants (parasitic green algae), snow banks and even on ice. They contain chlorophyll A and B and some green algae may contain a small amount of yellow pigment (Carotene) and brown pigment (Xantophyll). They store food in the form of the common plant starch and just like some plants, their cell walls contains carbohydrate cellulose.
In Philippines, some of the most common green algae are:
- Caulerpa (Ar-Arusip) in Ilocos Region
- Lato in Visayan Regions
- Codium (Pokpoklo) in Ilokano
- Ulva that are made into salad by housewives
Brown Algae have about 1500 species and most of it is a marine brown-colored algae which is commonly known as seaweeds. Brown algae make up Phylum Phaeophyta in Protista kingdom. The name comes from the Greek word “Phaios” which means “brown” and “phykos” for seaweed and “Phyton” for the plant.
Brown algae are known to be the largest of the algae. They are abundantly found in the tidal zones of temperate to polar seas and some do exist in Depth Ocean. An example of a giant brown algae includes:
- Giant Kelp
- Free-floating Sargassum weed
The brown pigment that is found in brown algae is called fucoxanthin, which along with other xanthophylls pigments covered the green pigment in the algal cells.
Brown algae are made up of multicellular and have diverse structures that resembles to the roots, leaves and stalks of a true plant. Though they are quite different internally, their cell walls are made of cellulose that is likely the same in red algae. The outsides of the walls are covered by a gelatinous pectic compound called algin. Brown algae such as kelp are harvested for economic, medicinal and food purposes:
- Emulsion stabilizer,
- An ingredient of ice cream
- Vitamin-containing food such as iodine.
Brown algae store food in the form of the two carbohydrates known as mannitol and laminarin.
Red algae belong to Phylum Rhodophyta, a large group of aquatic algae that is about 6000 species and only two percent are freshwater species. The name comes from the Greek word “Rhodon” which means “rose”, “Phykos” for “seaweed” and “Phyton” for the plant. Red algae are characterized by having reddish phycobilin pigments:
These pigments mask the color of the chlorophylls. Most red algae species thrive near tropical and subtropical shores below the low-tide mark and some are found in fresh water. They contain chlorophyll A and D. They store food in the form of carbohydrates known as “floridean” starch. The cell wall of red algae consists of cellulose and contains a gelatinous carbohydrate called agar.
Red algae have economic importance too. Agar is used for:
- Preparing gelatin, locally called “gulaman” for dessert.
- Used as a nutrient medium for growing bacteria and fungi
- Used in the food and drug industries, is obtained mostly from Gelidium and Gracilaria species.
- Carrageenin, obtained from Irish moss (Chondrus crispus), and is used as a substitute for gelatin.
- Laver (Porphyra) is used as a food in Japan and the Philippines.
Most multicellular red algae are small to medium in size. Their bodies are relatively complex just like in kelps. The sexual and reproductive structure of red algae is very specialized. They vary in shapes:
- Crustlike L
Golden algae are simple organisms that constitute Phylum Chrysophyta with about 10,000 species of unicellular freshwater and marine algae. The name comes from the Greek word “Chrysos” which means “gold”, “Phykos” for “seaweed” and “Phyton” for the plant.
The Chrysophytes are described by their yellowish xanthophyll pigments, which mask the green of the chlorophyll that is also present. Its cell walls contain silica or calcium. The three classes of golden algae are:
- Chrysophyceae ( yellow-brown algae)
- Xanthophyceae (yellow-green algae) -
- Bacillariophyceae (the diatoms) – Diatoms are microscopic unicellular algae which have varied shapes and designs.
Planktons are among the tiny floating organism. Phytoplanktons are tiny algae and other chlorophyll-bearing microorganism in water. On the other hand, zooplanktons are aquatic microorganisms which are not capable in performing photosynthesis.
Golden algae has chlorophyll A and C however, the green color is covered by the brown pigment xanthophylls (yellow pigment) called diatomin. They store food in the form of oil. Diatoms are the most well-known golden algae. They can be found in fresh water, seawater and in moist soil. Diatoms are characterized by:
- Having beautiful and geometrical design
- They have cell walls that contain the substance silica which gives them appearance of a glassy shell.
When diatoms die, the remains sink to the depth of the sea and through centuries, they form “diatomaceous earth” which is widely used by industries in making:
Dinoflagellates are single-celled aquatic organism that belongs to Phylum Pyrrophycophyta. The name comes from the Greek word “Pyrrhos” which mean “fire or flame”, “Phykos” for the plant. Below is a clear scientific classification of Dinoflagellates:
- Phylum: Pyrrophycophyta
- Order: Dinoflagellida
- Class: Phytomastigophorea
- Subphylum: Mastigophora
The phylum consist about 1050 species and most of them contains chlorophyll and are photosynthetic organism. There cells are either “naked or covered” with cell walls that is made up of polygonal plates of cellulose closely joined together. Most of them are marine organism in warm, shallow water that can reproduce in large numbers. This phenomenon is called a “bloom”.
Dinoflagellates contain green pigment chlorophyll A and C, and a brown pigment peridinin. Among of these are the diatoms which are the main producers of energy in the ocean food chain. Just like many complex unicellular organism, they have traits of both animals and plants that is the reason why zoologist claimed that they are “protozoans” and “algae” by botanists.
Some species of the genera Gymnodinium and Gonyaulax can produce a vile nerve toxin and can cause red tides. This phenomenon can cause enormous deaths of fishes, can contaminate mussels and clams and bad thing, can be deadly to human when eaten. However, some species of Dinoflagellates are beauty of the ocean for some produce bioluminescence.
References ; Science and Technology by Lilia M. Rabago Ph. D , Crescensia C. Joaquin Ph.D, Catherine B. Lagunzad , PH. D