Q.  Consider the following kinds of organisms: 

  1. Copepods
  2. Cyanobacteria 
  3. Diatoms
  4. Foraminifera

Which of the above are primary producers in the food chains of oceans?

  • 1 and 2 
  • 2 and 3 
  • 3 and 4 
  • 1 and 4 

Answer: b) 2 and 3 

Notes:

  • Primary producers are the organisms who synthesis their own food using photosynthesis or chemosynthesis.
    • Bacteria, Phytoplankton and algae form the bases of aquatic food webs.
      • They are eaten by primary consumers like zooplankton, small fish, and crustaceans.
      • Primary consumers are in turn eaten by fish, small sharks, corals, and baleen whales.
      • Top ocean predators include large sharks, billfish, dolphins, toothed whales, and large seals.
  • Consumers
    • Some zooplankton including copepods, rotifers, and larval stages of some fish and invertebrates are grazers and drift through the water grazing on phytoplankton.
    • Larger animals, including some marine snails, fish, reptiles, and mammals, graze on algae.
    • Filter feeders strain their food (plankton and detritus) directly from the water. Filter feeding animals include animals like bivalves, tube worms, sponges, and even large animals like baleen whales and manta rays.
  • Copepods are a group of small crustaceans found in nearly every freshwater and saltwater habitat. They are major primary consumers in the World Ocean. Copepods are generally herbivores, feeding only on plant plankton which they filter from the water. 
  • Cyanobacteria, also called blue-green algae, are microscopic organisms found naturally in all types of water. These organisms are primary producers who use sunlight to make their own food. 
  • Diatoms are photosynthesising algae. They are found in almost every aquatic environment including fresh and marine waters. They are primary producer in oceanic food chain. 
  • Foraminifera are single-celled organisms that are found in most marine environments. They are characterized by streaming granular ectoplasm for catching food. Foraminifera are heterotrophic organisms which consumes smaller organisms and organic matter.