Context
An article in the Hindu about plankton – Plankton balloon to six times their size to reach ocean surface
About Plankton
- Plankton are a diverse group of organisms that float in water (or air) and cannot swim against currents (or winds).
- They are carried by tides and currents, lacking the ability to swim against them.
- Size: Range from microscopic organisms to larger species like crustaceans and jellyfish.
- Types of Plankton:
- Phytoplankton: Plant-like organisms that perform photosynthesis and are crucial for oxygen production and carbon dioxide absorption.
- Examples: Cyanobacteria, diatoms, dinoflagellates.
- Zooplankton: Animal-like organisms that feed on phytoplankton. They include both microscopic animals and larger species like jellyfish.
- Examples: Radiolarians, krill, cnidarians.
- Phytoplankton: Plant-like organisms that perform photosynthesis and are crucial for oxygen production and carbon dioxide absorption.
- Role in Marine Food Web:
- Phytoplankton form the base of the marine food web, supporting marine life.
- Zooplankton feed on phytoplankton and, in turn, are prey for larger animals like whales.
- Zooplankton Migration: Zooplankton move to deeper waters during the day and rise to the surface at night to feed on phytoplankton.
- This process is the largest migration on Earth and can be observed from space.
- Habitat:
- Saltwater and Freshwater: Plankton live in both saltwater and freshwater ecosystems.
- Water Clarity: Turbid waters are often rich in plankton, while clearer waters indicate fewer plankton.
About Pyrocystis noctiluca and Vertical Migration
- Researchers focused on Pyrocystis noctiluca, a bioluminescent phytoplankton species capable of inflating its size during vertical migration.
- Size Expansion: It can inflate up to six times its original size (a few hundred microns), aiding in buoyancy.
- Vertical Migration: Many plankton move from the ocean’s cold depths to the surface and back, in a continuous cycle known as vertical migration.
- Movement Mechanism: For phytoplankton without swimming appendages, the movement mechanism remains largely unexplained.
- Density Dynamics: Phytoplankton are 5%-10% denser than seawater, making it challenging for them to remain near the surface for photosynthesis.
- Pyrocystis noctiluca: Acts like a submarine, controlling its density to reach the surface.
- Ballooning Mechanism: Researchers used a gravity machine to simulate ocean conditions, showing that inflated cells were less dense, allowing them to float to the surface.
Source: TH
Previous Year Question
Consider the following kinds of organisms:
1.Copepods
2. Cyanobacteria
3. Diatoms
4.Foraminifera
[UPSC Civil Services Exam – 2018 Prelims]
Which of the above are primary producers in the food chains of oceans?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 4
Answer: (b)
