What is plankton?
Q: What is plankton?
A: Plankton are drifting organisms that live in the surface layers of the ocean. They are not strong enough to swim against ocean currents and generally inhabit the top layer of the ocean, called the epipelagic zone.
Q: What are the three main groups of plankton?
A: The three main groups of plankton are phytoplankton, eukaryote algae, and bacteria. Phytoplankton live at the surface of the ocean and photosynthesise (use light to make sugars and other molecules). Eukaryote algae includes diatoms, coccolithophores, and some dinoflagellates. Bacteria includes cyanobacteria.
Q: What is zooplankton?
A: Zooplankton consists of small protozoans or metazoans such as ctenophores, jellyfish, rotifers, foraminifera, tiny crustacea and other animals. Some eggs and larvae of larger animals such as fish, crustaceans, and annelids also fall into this category. Apart from eggs they all feed on other plankton species.
Q: How do viruses fit into this scheme?
A: It is hard to fit viruses into this scheme; yet they are present in great numbers in oceans around the world.
Q: Why is it important for plankton to be part of an ocean's food chain?
A: Plankon are important in an ocean's food chain because they serve as a main source of food for almost all fish larvae when they switch from their yolk sacs to catching prey. Basking sharks and blue whales feed on them directly while other large fish feed on them indirectly by eating smaller fish like herrings.
Q: What governs where plankon can be found in an ocean? A: The distribution of plankon is governed more by nutrients than by temperature - areas near land masses tend to have more nutrients due to rivers or wind while large tracts with fewer nutrients may appear blue but sterile due to lack one or more crucial nutrient needed for photosynthetic plankon upon which all others depend (e.g., iron).
Q: How do mixotrophic species fit into this scheme? A: Mixotrophic species depend upon their circumstances - some dinoflagellates can be either photosynthetic producers or heterotroph consumers depending on what resources are available at any given time
