Plankton
Topic: Movements of Ocean Water: Waves, Tides and Currents · NCERT: Class 11, Ch 13 "Movements of Ocean Water"
Meaning
Plankton are tiny living things that drift with the water near the ocean's surface. There are two kinds: phytoplankton, which are tiny plants, and zooplankton, which are tiny animals. They are the main food of fish, so they sit at the base of the ocean food chain. They grow best in cool water full of nutrients. Such water is found where cold water rises from below (upwelling) and where warm and cold currents meet and mix.
Example
During the south-west monsoon, upwelling off the Kerala and Karnataka coasts brings up nutrients and plankton grow quickly. This supports the oil sardine and mackerel catch. In warm years the catch crashes.
Don't confuse with
- Phytoplankton and zooplankton: these are not separate groups from plankton. Both are types of plankton. Phytoplankton are plants, and zooplankton are animals that often feed on them.