Red Algae


Red algae can be witnessed in abundance in seaside atmospheres. However, they can also be witnessed in freshwater. It can be found both in the freshwater and marine which is one of the unique characteristics of red algae. Moreover, the visible growth pattern of the red algae is a diffuse pattern which includes apical growth and complex oogamy.

Figure 1: Red Algae

Red Algae Morphology

The morphology of the red algae varies in different forms due to the unicellular complexity found in the parenchymatous and non-parenchymatous thallus. Cellulose builds up the strength of the inside walls. In the red algae, three reproduction modes can be found, which are vegetative, asexual and sexual.

In the red algae, the cell walls are doubled. Red algae also have considerable gene-rich plastid genomes.

Figure 2: Red Algae Under Microscope

Cell Structure

In the complete life cycle of the red algae, they lack flagella and centrioles. Red algae consist of elements such as normal spindle fibres, un-stacked photosynthetic membranes, microtubules, phycobilin pigment granules, pit connections that defines the structure of the cells of red algae. Moreover, chloroplast endoplasmic reticulum is not available in its cells.


The existence of pigments soluble in the water, recognised as the phycobilins, gives red algae cells the hue. Thylakoids are circulated in a uniform order and ungrouped in the chloroplast. The available other pigments are the Chlorophyll a, α- and β-carotene, lutein, and zeaxanthin. The chloroplast is usually encircled by the double membrane of the envelope of the chloroplast. Red algae also lack grana and phycobilisomes.

Storage Products

Different environmental factors such as pH, light intensity, medium salinity, and other elements affect the concentration of the photosynthetic derivatives. For instance, floridoside production increases with increase in the medium salinity to prevent the water from the exiting the cells of the red algae. The floridean starch is deposited freely in the cytoplasm as a storage product for the long term.

Pit Connections

During the cytokinesis cycle after mitosis, the primary traits of the red algae such as the pit connections and pit plugs are formed. In red algae, cytokinesis are not complete. Due to the remaining contact of the daughter’s cell, the establishment of the pit connection occurs.

In the red algae, the red cells have two primary pit connections, one each to the next cell, due to the apical development.

There are tubular membranes created during a pit connection which eventually fades away with time.

Reproduction of Red Algae

The reproductive cycle of the red algae can be initiated by various situation that includes the length of the day. One of the unique factors that are recognisable in the red algae is it can reproduce asexually, vegetative, and sexually. The reproductive system is dependent on some external factors. With the spore formation, asexual reproduction takes place in the red algae. Through cell division, vegetative reproduction can be seen in the red algae.

The followings are the associated steps of the reproductive cycle of the red algae −


The sperm in red algae are not motile. Consequently, they depend on currents of the water to reposition their gametes to the female organs, although their sperm can glide to the trichogyne of a carpogonium. Trichogyne will continue its growth unless it comes in contact with a spermatium. Once the fertilisation is complete, the cell wall at its base thickens, isolating it from the rest of the carpogonium.

Life cycle

Red algae shows alternation of generation. The generation of the carposporophyte can produce the carpospres which germinates into tetrasporophyte. Tetrasporangia produces the gametophyte.

Applications of Red Algae

The ecological significance of the red algae is higher at present. They are an essential element of the food chain. In aquatic habitats it’s recognised as they can produce 40-60% of oxygen. The followings are the vital application of red algae for different purposes −

  • Algae is a natural food for aquatic creatures.

  • They are a source of vitamins, magnesium, calcium, and antioxidants.

Figure 3: Edible Red Algae

  • They are able to deliver dietary fibre.

  • Red algae are used in the cosmetics products that are used for nourishing skin.


In nearly 5% of overall freshwaters, red algae can be encountered, with higher engagements in warmer backgrounds. The uniqueness that can be discovered in the red algae is in the last general ancestors which are only 25% of its core gene.


Q1. What are red algae?

Ans. There are around six thousand species of eukaryotic algae which is recognised as the red algae. It found in freshwater as well as marine. The presence of the chlorophyll made them visible as red coloured.

Q2. What are the significances of red algae?

Ans. Red algae are usually found in the marine and freshwater. They supply oxygen at a higher level. Additionally, they provide food for the animals in the water. Due to them, aquatic animals receive vitamins, calcium, and other supplements.

Updated on: 13-Apr-2023


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