Unseen Passage: Pond Ecosystem

A pond ecosystem, a basic unit in ecology formed from the cohabitation of plants, animals, microorganisms, and a surrounding environment, refers to a community of freshwater organisms largely dependent on each of the surviving species to maintain a life cycle. Ponds shallow water bodies barely reach 12 to 15 feet indepth and allow the sun to penetrate to its bottom, allowing freshwater plants to grow. A pond ecosystem consists of algae, fungi, microorganisms, plants, and various fish, which may fall into three distinct classifications: producer, consumer, and decomposer. The pond’s natural cycle begins with the producers and then to the consumers before ending with the decomposers.

A pond’s ecosystem consists of abiotic environmental factors and biotic communities of organisms. Abiotic environmental factors of a pond’s ecosystem include temperature, flow, and salinity. The percentage of dissolved oxygen levels in a water body determines what kind of organisms will grow there. After all, fish need dissolved oxygen in order to survive; however, anaerobic bacteria will not thrive in an ecosystem pumped with dissolved oxygen. A water body’s salinity may also determine the different species present. For instance, marine organisms tolerate salinity, while freshwater organisms will not thrive when exposed to salt. In fact, freshwater ecosystems often have plant species present which will absorb salts that are dangerous for freshwater organisms.

A pond ecosystem consists of four habitats, including the shore, surface film, open water, and bottom water. The shore, depending on its rocky, sandy, or muddy composition, lures in various organisms. For instance, rocky shores may not allow plants to grow, while muddy or sandy shores attract grasses, algae, earthworms, snails, protozoa, insects, small fish, and microorganisms. The pond’s surface breeds excellent ground for water striders, marsh traders, free-floating organisms, and organisms that can walk on the surface of water. An open-water habitat permits sizable fish, plankton, phytoplankton, and zooplankton to grow. Phytoplankton includes a large variety of algae, while zooplankton refers to insect larvae, rotifers, small crustaceans and invertebrates. Fish feed on plankton, or tiny organisms. The bottom-water habitat varies depending upon the pond’s depth. Shallow ponds with sandy bottoms provide a nesting environment for earthworms, snails, and insects. Deep-ended ponds have muddy bottoms, which allow various microorganisms, such as flatworms, rat-tailed maggots, and dragonfly nymphs to reproduce and survive.

Q. On the basis of your reading and understanding of the above passage, answer the following:

  1. Which type of organisms is found in the pond ?
  2. What does a fish need to survive ?
  3. Zooplankton are insect larvae, rotifers, small crustaceans invertebrates. (True/False)
  4. Where are flatworms found ?
  5. Which two organisms cannot thrive together ?
    1. anaerobic bacteria and algae
    2. fish and anaerobic bacteria
    3. protozoa and fish
    4. earthworms and flatworms
  6. The shore of a pond with grasses and snails can be
    1. sandy
    2. muddy
    3. both (1) and (2)
    4. either (1) or (2)
  7. Which among the following doesn’t determine the type of species in a water body ?
    1. penetration of sunlight to the bottom
    2. percentage of oxygen present
    3. salinity
    4. none of the above
  8. Choose the option which doesn’t have the correct pair of organism and habitat.
    1. marsh traders – bottom of the pond
    2. snail – shore of the pond
    3. water striders – surface of the pond
    4. rotifers – open water of the pond


  1. Freshwater organisms
  2. Dissolved oxygen
  3. True
  4. In deep-ended ponds with muddy bottoms.
  5. fish and anaerobic bacteria
  6. either (1) or (2)
  7. none of the above
  8. marsh traders – bottom of the pond

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