Knowing the Indian Ocean

After the Pacific and the Atlantic, let’s move onto the Indian ocean

Photo by Asad Photo Maldives on

Hope you remember the acronym- PAISA

  1. Pacific
  2. Atlantic
  3. Indian
  4. Southern
  5. Antarctic

These oceans are arranged in the decreasing order of their sizes.

The third largest ocean based upon its size, it is the only ocean in the whole world to be named after a country. It covers 27,240,000 sq ml or 19.8 percent of the world’s water on the Earth’s surface. Bounded by Asia to the north, southern ocean to the south, Africa to the west and the Indonesian islands (the strait of Malacca) and Australia to the east, it also hass many marginal seas and islands.

Marginal Seas:

  1. Bay of Bengal
  2. Arabian sea
  3. Laccadive sea
  4. Java sea
  5. Andaman Sea
  6. Timor Sea
  7. Red sea
  8. Persian Gulf
  9. Gulf of Aden
  10. Gulf of Oman
  11. Gulf of Suez
  12. Molucca sea
  13. Gulf of Khambhat

Major islands

  1. Andaman and Nicobar
  2. Lakshadweep
  3. Maldives
  4. Madagascar
  5. Reunion
  6. Seychelles
  7. Mauritius
  8. Comoros
  9. Indonesia

Enclosed by land on three sides, it is centered along the Indian peninsula and doesn’t extend from pole to pole. It has roughly 800 drainage basin of which 50% are located in Asia, 30 % in Africa and 20% in Australia. It is considered to have subtropical climate. The northern half of the Indian ocean experience monsoon winds that lead to reversal in direction of winds (caused by the movement of ITCZ that in summers reaches above the Tibetan plateau, due to the apparent movement of sun) during summers and winters. This brings the monsoon winds to India during the rainy season(80% of the Monsoon rains dependent on them).

40 % of the total sediments found in this ocean are the results of deposition of the Ganga and Indus fans, the largest submarine fans of the world. The western Indian ocean has the largest phytoplankton blooms in summer due to the monsoon winds (they lead to the ocean water upwelling, building nutrient rich cold water to the surface of the ocean). These phytoplankton later support a complete ecosystem, acting as the primary food producers in the chain, in the ocean leading to high concentration of fish and other marine organisms. Thus, harm to the growth of these phytoplankton (continuously on the rise due to global warming, dumping of acidic and industrial waste water and algae bloom) can further destroy the fragile marine ecosystem.

There are 10 large marine ecosystems in the Indian Ocean-

  1. Agulhas current
  2. Somali coastal current
  3. Red sea current
  4. Persian gulf current
  5. Arabian sea
  6. Bay of Bengal
  7. Gulf of Thailand
  8. West central Australian shelf
  9. Northwest Australian shelf
  10. Southwest Australian shelf

Coastal reefs, sea grass bed and Mangrove forest: The most productive and important ecosystems. This ocean has 36 biodiversity hotspots and is an actively spreading and expanding ocean(having only two trenches- The Java and Sunda trench and the Makaran trench). It also has an active volcanic hotspot- The Reunion hotspot(currently below the reunion islands). Salinity follows the trends similar to the Atlantic ocean(though it doesn’t extend towards the poles.)

This is all about the Indian ocean. See you tomorrow with the Southern ocean.