Microscopic aquatic organisms lacking locomotory ability and drifting with water currents are :

Question

Accepted Answer

Microscopic aquatic organisms lacking locomotory ability and drifting with water currents are known as plankton. Let's delve into why Option 2, "Plankton," is the correct answer and why the other options are not suitable.

1. **Plankton (Option 2):** Plankton are small and microscopic organisms that float or drift in water, primarily in oceans and freshwater bodies. They lack the ability to swim against the current, which is a defining characteristic of plankton. Plankton can be further categorized into phytoplankton (plant-like organisms) and zooplankton (animal-like organisms). Their inability to move independently and reliance on water currents for movement aligns perfectly with the description given in the question.

2. **Pleuston (Option 1):** Pleuston are organisms that live at the interface of air and water, often floating on the surface. While they may drift with water currents, they are not exclusively microscopic, and their habitat is distinct from that of plankton. Pleuston can include larger organisms like certain types of algae and insects, which do not fit the description of microscopic organisms lacking locomotory ability.

3. **Necton (Option 3):** Necton refers to aquatic animals that can swim actively and independently of water currents. Examples include fish, squid, and marine mammals. This is in direct contrast to the organisms described in the question, which lack locomotory ability. Therefore, necton is not a suitable answer.

4. **Saston (Option 4):** The term "saston" is not a recognized category in marine biology or ecology. It does not correspond to any known group of aquatic organisms, making it an incorrect option in this context.

In conclusion, plankton is the correct answer because it accurately describes microscopic aquatic organisms that drift with water currents due to their lack of independent movement. The other options do not fit the criteria outlined in the question.