GOMPHONEMA RAJAGURUII
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Context
- Researchers at the Pune-based Agharkar Research Institute (ARI) have discovered a new species of single-cell algae, known as diatoms, from the northern Western Ghats — and named it after a veteran geo-archaeologist from the city, the late Professor S N Rajaguru.
S N Rajaguru was a former faculty member of Deccan College and known for his attempts to link biological and archaeological remains during excavations. It was through Rajaguru’s extensive studies that researchers today have a clear time-frame of India’s paleo-environment. He retired in 1994 as Joint Director of Deccan College, and passed away in December 2022. |
About the new species
- The new species named Gomphonema rajaguruii was found in a semi-aquatic environment along the wet walls in Maharashtra's popular hill station Mahabaleshwar in Satara district.
- Gomphonema rajaguruii is unique because it shows the characteristics of two genus — Gomphonema and Gomphoneis.
- This is a freshwater diatom species.
- Diatoms showcasing such dual characteristics are very rare.
- Diatoms can be found in freshwater and brackish water, and are commonly traced in lakes, rivers, streams, rivulets and the sea.
- Similar to plants and trees that produce oxygen during the process called photosynthesis, diatoms, too, supply oxygen to the atmosphere.
About Diatom
- A diatom is a unicellular eukaryotic alga characterized by having a siliceous covering and a symmetrical body.
- Diatoms are mostly aquatic, being found in fresh, brackish, and saltwater. Some are found in moist places, such as soil.
- Diatoms comprise the taxonomic phylum Bacillariophyta.
- They may be solitary or in colonies. When in colonies, they form various shapes, e.g. ribbons, zigzags, stars, or fans.
Classification of Diatoms
- The phylum Bacillariophyta includes the diatoms. The taxonomic classes of diatoms under Bacillariophyta are as follows:
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- Coscinodiscophyceae (centric diatoms)
- Fragilariophyceae (araphids, i.e. pennate diatoms without a raphe)
- Bacillariophyceae (raphids, pennate diatoms with a raphe)
General Characteristics
Unicellularity
- Diatoms are a major group of microscopic algae and are among the most common types of phytoplankton.
- Diatoms are unicellular.
- The cell size may range from 2 to 200 micrometers. They may live singly or in colonies.
Frustule
- A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (i.e. hydrated silicon dioxide).
- The siliceous cell wall is called a frustule.
Thecae
- Diatom cell has two distinct halves: the hypotheca (the slightly smaller theca) and the epitheca (the slightly larger theca.
Pigments
- Diatoms have yellowish-brown to olive-brown chloroplasts due to the predominance of carotenoids (fucoxanthin), and xanthophylls. Their chloroplasts are four-membraned.
Nutrition
- Most diatoms are photosynthetic whereas a few of them are heterotrophs.
Food reserve
- Their carbohydrate reserve is chrysolaminarin. They also store lipids.
Lacking flagella
- Diatoms do not have flagella except for the male gametes of centric diatoms that have smooth flagella.
Reproduction
- Diatoms reproduce asexually by binary fission.
Buoyancy
- Diatoms are able to stay suspended through various mechanisms.
Ecology
- Diatoms are referred to as the jewels of the sea because of their structural coloration. They are major oxygen producers on Earth. They generate about 20% oxygen annually.
PRACTICE QUESTION Q) Which of the following statements with reference to Diatoms is/are correct? 1. All diatoms are photosynthetic. 2. Diatoms are referred to as the jewels of the sea. 3. A diatom is a unicellular eukaryotic alga.
Correct Answer: b |