Question

The upper part of seawater mainly contains
A. Nektons only
B. Planktons only
C. Nektons and planktons both
D. None of the above

Answer 1

Hint: The upper zone of the ocean is known as the surface mixed zone. It is created by warm temperatures as well as the mixing of tides and currents. Aquatic organisms live in the water bodies and depend on it for their survival. Almost 71% of the earth is covered with water.

Complete answer: Planktons literally means drifters and includes all organisms that drift along with the ocean currents. Both algae and bacteria come under plankton. Nektons are animals that have the capability to swim. It includes fish, marine mammals, and marine reptiles. Marine organisms can be classified according to two criteria - where they live and how they move. They can be classified as either plankton (floaters) or nekton (swimmers). Among planktons, the algae that perform photosynthesis are called phytoplankton. Most phytoplankton, such as diatoms, are microscopic. Animal planktons are also called zooplankton. Nekton includes all animals that are capable of moving independently of the ocean currents, by swimming or other means of propulsion. Nekton is able to determine its position in the ocean currents and in many cases complete long migrations. Some examples of nektons are adult fish and squid, marine mammals, and marine reptiles. Nekton includes fish, squid, marine mammals. They live in the sea, lakes, rivers, ponds, and other forms of water bodies.

Note: Plankton is a diverse group of organisms that is defined by its inability to swim actively against a current, rather than by biological factors. Mostly planktons are less than an inch long. They can be called marine plants as they have chlorophyll to capture sunlight and like land plants, they perform photosynthesis to convert light into energy.