NCERT Solutions for Class 5th The World Around Us Chapter 6 Marine Interpretation Centre; North Sentinel Island — Discuss

Book page 98 Updated on2026-09-19

Q1.
Why do you think life under the sea is just as important as life in the forests?
Answer

Because the sea does the same jobs a forest does, and a few more. We notice a forest because we can walk into it. The sea does its work out of sight, so it is easy to forget.

JobHow a forest does itHow the sea does it
Makes the oxygen we breatheTrees make oxygen in their leavesTiny floating sea plants make a very large part of the world's oxygen
Gives foodFruit, honey, roots, leavesFish, prawns, crabs and salt — the daily food of millions of Indians
Gives workForest produce, honey collectingFishing, boat making, net making, ports, tourism
Keeps the weather steadyTrees cool the air and bring rainThe sea heats slowly, sends up the vapour that becomes our monsoon rain
Protects the landRoots hold the soil on hillsidesCoral reefs and mangroves break big waves before they hit the shore
Home for living thingsTigers, birds, insects, orchidsCorals, fish, turtles, dolphins — countless kinds, many still unknown
The idea to hold on to: everything is joined. A reef shelters small fish; the small fish feed big fish; the big fish feed people in the fishing village; the village keeps the harbour going. Damage the reef and every link after it suffers. The chapter says the same thing at the end — everything is connected.
For your discussion: Ask one another, "name three things in your house that came from the sea." Salt, dried fish, a shell, a pearl button, sand in the cement of the wall. The list gets longer than anyone expects.
Q2.
How do you think the coral reef helps the fish and other sea creatures?
Answer

A coral reef is a town under the sea. It gives sea creatures the three things every living thing needs — a home, food and safety.

  1. A home. A reef is full of holes, cracks and branches. Small fish, crabs, prawns and eels slip inside and live there.
  2. A hiding place. When a big fish comes, the small ones dart into a hole. Their bright stripes and spots also match the colours of the coral, so they are hard to spot.
  3. A safe nursery. Many fish lay their eggs on a reef. The baby fish grow up in the shelter of the coral before they go out into open water.
  4. Food. Tiny plants and animals grow all over the coral. Small fish eat them; bigger fish come to eat the small fish. The whole food chain starts here.
  5. A shield for the shore. A reef stands like a low wall across the path of the waves. Waves break on it and reach the beach much weaker.
What a coral actually is: a coral is a tiny, soft sea animal. It builds a hard stony cup around itself for protection. Millions of them live side by side, and when the old ones die the new ones build on top. Over hundreds of years those stony cups pile up into the ridge we call a reef. So a reef is really a huge block of flats built by very small animals.
Where to see reefs in India: around the Andaman and Nicobar Islands, in Lakshadweep, in the Gulf of Mannar off Tamil Nadu, and in the Gulf of Kachchh in Gujarat. Corals need clean, clear, warm water — muddy or dirty water kills them.
Q3.
How do you think their knowledge might have helped the people of North Sentinel Island stay safe?
Answer

They knew their island so well that they read nature's warning and moved to high ground before the tsunami reached them.

A tsunami is a huge sea wave, usually caused by a strong earthquake under the sea floor. In December 2004 one struck this region. The Sentinelese survived it.

The signs they would have noticed:

  1. The ground shook. An earthquake comes first. People who live close to the earth feel it at once.
  2. The sea pulled back. Before a tsunami, the water often draws far away from the shore and the sea floor is left bare. Anyone who watches the sea every day of their life knows that this is wrong.
  3. The wind and the sound changed. A strange roar comes from the sea before the wave.
  4. The animals behaved oddly. Birds flew inland in flocks. Animals went uphill and would not come down. Living so close to animals, the Sentinelese would have seen it immediately.
  5. They moved. They went inland and uphill, away from the beach, and waited.
Why this counts as knowledge: They had no radio, no phone and no warning system. What they had was a lifetime of watching one place very closely, and stories handed down from their elders about what to do when the sea behaves like that. That is real knowledge — passed on by word of mouth, tested over hundreds of years, and it saved them.
An important rule: The Sentinelese do not want visitors. Nobody is allowed to go to North Sentinel Island. This is not unfriendliness — it protects them. They have no protection against our common illnesses, so a single visitor could make many of them very ill. Leaving them alone is the respectful thing to do.
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