Read the paragraph and answer the Question given below:
There is no natural habitat on earth known that is inhabited just by a single species. For any species, the minimal requirement is one more species on which it can feed. Even a plant species, which makes its own food, cannot survive alone and needs soil microbes to break down the organic matter in soil and return the inorganic nutrients for absorption. It is obvious that in nature, animals, plants and microbes do not and cannot live in isolation but interact in various ways to form a biological community.
Which of the following set of organisms is an example of commensalism?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Sea anemone and clown fish
Option (1) Pisaster (starfish) and some invertebrates — Incorrect. This is predation. Pisaster preys on invertebrates of the rocky shore. When all the starfish were removed, more than 10 invertebrate species died out within a year because of competition among them.
Option (2) Abingdon tortoise and goats — Incorrect. This is competition. The Abingdon tortoise of the Galapagos Islands became extinct within a decade after goats were brought in, because the goats browsed more efficiently.
Option (3) Sea anemone and clown fish — Correct. The clown fish gains protection from predators, and the anemone neither gains nor loses.
Option (4) Flamingo and resident fishes — Incorrect. This is competition between unrelated species. Both feed on the zooplankton of shallow South American lakes.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Population Interactions – “… (iv) Commensalism: This is the interaction in which one species benefits and the other is neither harmed nor benefited. An orchid growing as an epiphyte on a mango branch, and barnacles growing on the back of a whale benefit while neither the mango tree nor the whale derives any apparent benefit. The cattle egret and grazing cattle in close association, a sight you are most likely to catch if you live in farmed rural areas, is a classic example of commensalism. The egrets always forage close to where the cattle are grazing because the cattle, as they move, stir up and flush out insects from the vegetation that otherwise might be difficult for the egrets to find and catch. Another example of commensalism is the interaction between sea anemone that has stinging tentacles and the clown fish that lives among them. The fish gets protection from predators which stay away from the stinging tentacles. The anemone does not appear to derive any benefit by hosting the clown fish.”