Reading Comprehension Exercises for Grade 4

The passage about partnerships among animals is an excellent reading comprehension exercise for Grade 4 students.

Partnerships In The Animal Kingdom

Many animals form partnerships with other animals. These partnerships last for a variable length of time. Partnerships between two different species of animals are known as symbiotic relationships. There are three different kinds of symbiosis. These are mutualism, commensalism and parasitism.

Mutualism is a symbiotic relationship which benefits both partners. Such a relationship can be seen when a crocodile opens its mouth and allows a bird to walk in to peck at the food particles stuck between its teeth. The crocodile ends up getting its teeth cleaned while the bird gets free food.

Commensalism is a relationship that benefits only one of the partners of a symbiotic relationship. The other partner does not benefit from the relationship but neither is it harmed. An example of such a relationship exists between the shark and the remora fish. The shark provides the remora fish with transportation by allowing it to ride on its back and belly.

Parasitism is a relationship where one partner benefits at the expense of the other partner. A parasite obtains its food from its host. It does not steal too much nourishment lest the host dies. Should this happen, the parasite would have to look for another host. For example, a tapeworm can live in a man’s intestine and feed on the products of digestion.

There are thousands of examples of symbiotic relationships occurring in nature. Scientists have studied some of these relationships, but there are many more which we still do not understand. An interesting symbiotic relationship that has been studied in great detail is the partnership between the sea anemone and the clown fish.

The sea anemone has wavy tentacles and looks like a plant. When a fish swims among the tentacles of a sea anemone, it is stung by the poisonous tentacles. The fish dies and is eaten by the sea anemone. However, the clown fish is able to move among the tentacles of the sea anemone without getting stung. The clown fish is a very colourful, small fish. Its bright colours make it difficult for it to hide from predators. To protect itself from bigger fish, the clown fish hides among the tentacles of the sea anemone. The body of the clown fish develops a film of mucus which protects the fish against the poison of that particular sea anemone. The sea anemone also benefits from the situation. The presence of the colourful clown fish lures bigger fish towards it. Tempted by the sight of a meal that does not try to escape from them, the bigger fish fail to notice the tentacles of the sea anemone. They swim among the tentacles, only to be stung and eaten by the sea anemone.

Symbiosis occurs among plants too. It is not an accidental occurrence but is an integral part of their lifecycle.

Comprehension exercises

1. Can you spot the words in the passage that have the meanings given below? The number of the paragraph where the word appears is given in brackets.
a) can be changed (paragraph 1)
b) food for growth (paragraph 4)
c) happening (paragraph 5)
d) tempts (paragraph 6)
e) vital/very important (paragraph 7)

2. Write answers to the following questions in complete sentences.
a) What are the three types of partnerships found in the animal kingdom?
b) Explain the symbiotic relationship between a crocodile and a bird.
c) Give an example of commensalism in the animal kingdom.
d) Give an example of parasitism in the animal kingdom
e) Explain the symbiotic relationship between the sea anemone and the clown fish.

Answers

• a) variable
  b) nourishment
  c) occurring
  d) lures
  e) integral
• a) The three types of partnerships found in the animal kingdom are mutualism, commensalism and parasitism.
  b) A crocodile opens its mouth and allows a bird to walk in to peck at the food particles stuck between its teeth. The crocodile ends up getting its teeth cleaned while the bird gets free food.
  c) An example of commensalism is that which exists between the shark and the remora fish. The shark provides the remora fish with transportation by allowing it to ride on its back and belly.
  d) A tapeworm can live in a man’s intestine and feed on the products of digestion. This is an example of parasitism.
  e) The clown fish is a small, colourful fish. Its bright colours make it difficult for the fish to hide itself from the bigger fishes that prey on it. To protect itself, the clown fish lives among the tentacles of the sea anemone. The sea anemone is a creature with poisonous tentacles. When a fish which wants to feed on the clown fish swims close to the tentacles of the sea anemone, the fish will be stung by the poisonous tentacles. The fish will die and be eaten by the sea anemone. The clown fish is protected from the sea anemone by the film of mucus covering its body.