Into the Depths of the Indian Ocean

The Indian ocean being the world’s third biggest ocean covering 7,05,60,000 sq km which is 19.5% of Earth’s water surface and 19.8% of the global ocean volume is the least understood ocean among the 5 oceans with complex geomorphology. The Indian ocean has subduction trenches, seamounts, ridges, plateaus, coral atolls, fracture zones and hydrothermal vents but is scientifically neglected for years.

The Java trench is the deepest subduction trench in the Indian ocean and also the only trench which exceeds the hadal zone (more than 6000m water depth). Java trench is also called Sunda trench which is 2000m long and 7290m deep. As a part of the Pacific ring of fire, the Java trench starts from the Lesser Sunda Islands past Java, around the southern coast of Sumatra on to the Andaman Islands, and forms the boundary between Indo-Australian Plate and Eurasian plate.

The study on Java trench is recent and because of its depth this trench has an isolated geographical hadal ecosystem. It has a temperature of 1.54°C with fine grained sediment plateaus. The Java trench has 10 phyla, 21 classes, 34 orders and 55 families. There are 36 chemosynthetic bacteria mat deposits of orange, yellow, and white in color. The trench is populated by hexactinellid sponges. Holothurians like Amperima cf. naresi, Elpidia cf. sundensis, Enypniastes sp., Psychropotes sp., Elpidia cf. sundensis, Munnopsid isopod. Actiniarias like Galatheanthemum and Bathyphellia, Snailfish, Echinoderms like the asteroid Hymenaster sp., unidentified Ophiuroid sp., fragile, semi-transparent Crinoids, unidentified crinoid, and unidentified Ophiuroid sp., the polynoid polychaete, Macellicephaloides. Amphipods like the supergiant Alicella gigantea, Bathycallisoma schellenbergi, the unidentified Stegocephalidae species, and the pardaliscid Princaxelia, the Mysid Amblyops sp., the stalked ascidian, Culeolus sp, echinoderms like ophiuroids or brittle stars (Ophiuroidea), asteroids or sea stars (Asteroidea), and crinoids or feather stars (Crinoidea), 98 unidentified ophiuroids (Ophiuroid sp. 1), Anemone Galatheanthemum, Anemone Bathyphellia, Polynoidae Macellicephaloides, mysid Amblyops sp., Alicella gigantea, Princaxelia, Bathycallisoma schellenbergi, Stegocephalidae sp,. Grimpoteuthis sp., larvaceans, 7 Ophidiidae species, 1 Ateleopodidae species and 1 liparid species are discovered in the deepest point of the Indian ocean. The Java trench is still highly unexplored and has undiscovered and undescribed life forms.

Inside the least studied ocean within the least explored trench with many unidentified species, plastic and man made metal items were found proving that there is no “pristine” wilderness left neither on land nor in the deep oceans.


Published by LakesOfIndia

Lakes of India is an E.F.I initiative aimed at sensitizing the larger public on freshwater habitats across the country. A blog platform where one can read about lakes across India. You can become a guest blogger to write about a lake in your hometown and initiate an action to protect that lake.

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