What is Algae?
|➧ Definition of Algae
❖ Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic organisms.♦ Let’s discuss all the bold terms one by one.
• Contain 5 types of Chlorophyll (Chlorophyll a to Chlorophyll e)◘ Thalloid body (Thallus structure)
• Thalloid means a flat body with no differentiation into roots, stem and leaves.
• Just remember the word “Thali or Thela” which means Plate or dishes, and a plate contain only circular body. They don’t have legs (roots in case of algae) or head (Stem and leaves in case of algae).
Habitat of Algae
|◘ They occur in a variety of habitats like moist stones, soils and wood. Some of them also occur in association with fungi (lichen) and animals (e.g., on sloth bear).
➧ Cryophytic Algae
➧ Thermophytes / Thermal algae
➧ Epiphytic algae
➧ Halophytic algae
➧ Lithophytes algae
➧ Aquatic algae
➧Marine water algae
➧ Parasitic algae
Form and Size of Algae
|◘ The form and size of algae is highly variable.
• Algae range in size from picoplankton ( 0.2 to 2 micrometers in diameter) to giant kelp (large brown algae), which can be 50 metres (160 feet) long.
♦ Macrocystis pyrifera
Types of Reproduction method in Algae
|♦ The algae reproduce by 3 methods ….
◘ 1. Vegetative mode of reproduction.
◘ 2. Asexual mode of reproduction
◘ 3. Sexual methods of reproduction♦ Vegetative reproduction is by fragmentation. Each fragment develops into a thallus.♦ Asexual reproduction is by the production of different types of spores
• The most common being the zoospores.
• Zoospores are flagellated and motile
• The Zoospores germinate to gives rise to new plants.
♦ Sexual reproduction takes place through fusion of two gametes.
◘ Isogamous reprodution
◘ Anisogamous reprodution
◘ oogamous reprodution
Types of Algae
|◘ The algae are divided into three main classes ….
• 1. Chlorophyceae (Green algae)
• 2. Phaeophyceae (Brown algae)
• 3. Rhodophyceae (Red algae )➲ Chlorophyceae (Green algae)
◘ Plant body of Green algae
▶ Plant body may be ….
• Filamentous◘ Types of chlorophyll in Green algae
▶ Always grass green due to the dominance of two pigments.
• Chlorophyll a and
• Chlorophyll b
◘ Shape of chloroplasts in Green algae
◘ Storage body of Green algae
◘ Cell wall of Green Algae
◘ Reproduction mode of Green Algae
◘ Example of Green Algae
➲ Phaeophyceae (Brown algae)
◘ Types of chlorophyll in Brown Algae
◘ Food storage in Brown Algae
◘ Cell wall of Brown Algae
◘ Reproduction in Brown Algae
◘ Example of Brown Algae
➲ Rhodophyceae (Red algae)
◘ Pigments in Red Algae
◘ Storage in Red Algae
◘ Reproduction in Red Algae
◘ Example of Red Algae
Main Characteristics of Algae in Brief Tabular format
|Classes||Common Name||Major Pigments||Stored Food||Cell Wall|
|Chlorophyceae||Green algae||Chlorophyll a, b||Starch||Cellulose|
|Phaeophyceae||Brown algae||Chlorophyll a, c,
|Mannitol, laminarin||Cellulose and algin|
|Rhodophyceae||Red algae||Chlorophyll a, d
|Floridean starch||Cellulose, pectin and
poly sulphate esters