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An overview

[http://andssw1.and.nic.in/dsc/Common/FloraFauna.htm#:~:text=%22The%20South%20Andaman%20forests%20have,with%20plenty%20of%20woody%20climbers. District and Sessions Court/ Andaman and Nicobar Islands]

These Islands are blessed with a unique' luxuriant evergreen tropical rainforest canopy, sheltering a mixed germ plasm bank, comprising of Indian, Myanmarese, Malaysian and endemic floral strain. So far, about 2200,varieties of plants have been recorded out of which 200 are endemic and 1300 do not occur in mainland India."

The South Andaman forests have a profuse growth of epiphytic vegetation, mostly ferns and orchids. The Middle Andamans harbours mostly moist deciduous forests. North Andamans is characterised by the wet evergreen type, with plenty of woody climbers. The north Nicobar Islands (including Car Nicobar and Battimalv) are marked by the complete absence of evergreen forests, while such forests form the dominant vegetation in the central and southern islands of the Nicobar group. Grasslands occur only in the Nicobars, and while deciduous forests are common in the Andamans, they are almost absent in the Nicobars". This atypical forest coverage is made-up of twelve types namely (1) Giant evergreen forest (2) Andamans tropical evergreen forest (3) Southern hilltop tropical evergreen forest (4) Cane brakes (5) Wet bamboo brakes (6) Andamans semi-evergreen forest (7) Andamans moist deciduous forest (8) Andamans secondary moist deciduous forest (9) Littoral forest (10) Mangrove forest (11) Brackish water mixed forest (12) Submontane hill valley swamp forest. The present forest coverage is claimed to be 86.2% of the total land area.

TIMBER

Andaman Forest is abound in plethora of timber species numbering 200 or more, out of which about 30 varieties are considered to be commercial. Major commercial timber species are Gurjan (Dipterocarpus spp.) and Padauk (Pterocarpus dalbergioides). Ornamental wood such as

(1) Marble Wood (Diospyros marmorata) (

2) Padauk (Pterocarpus dalbergioides),

(3) Silver Grey (a special formation of wood in white chuglam)

(4) Chooi (Sageraea elliptical and

(5) Kokko (Albizzia lebbeck) are noted for their pronounced grain formation.

Padauk being steadier than teak is widely used for furniture making. Burr and the Buttress formation in Andaman Padauk are World famous for their exceptionally unique charm and figuring. Largest piece of Buttress known from Andaman was a dining table of 13'x 7'. The largest piece of Burr was again a dining table to seat eight persons at a time. The holy Rudraksha (Elaeocarps sphaericus) and aromatic Dhoop/Resin trees also occur here.

FAUNA

This tropical rain forest despite its isolation from adjacent land masses is surprisingly enriched with many animals.

MAMMALS

About 50 varieties of forest mammals are found to occur in A&N Islands, most of them are understood to be brought in from outside and are now considered endemic due to their prolonged insular adaptation.

Rat is the largest group having 26 species followed by 14 species of bat.

Among the larger mammals there are two endemic varieties of wild pig namely Sus Scrofa andamanensis from Andaman and S.S.nicobaricus from Nicobar.

The spotted deer Axis axis, Barking deer and Sambar are found in Andaman District.

Interview island in Middle Andaman holds a fairly good stock of feral elephants. These elephants were brought in for forest work by a private contractor who subsequently left them loose.

Butterflies and Moths

With about 225 species, the A&N Islands house some of the larger and most spectacular butterflies of the world. Ten species are endemic to these Islands. Mount Harriet National Park is one of the richest areas of butterfly and moth diversity on these Islands.

Shells

Shells are perhaps the most colourful and fascinating objects known to man other than Gems since time immemorial. They served as money, ornaments, musical instruments, drinking cups, in magic and in the making of fine porcelains. They were also the symbols in rituals and religious observances, and the returning pilgrims wore them as a token of divine pardon. These islands are traditionally known for their shell wealth specially Turbo,Trochus, Murex and Nautilus. Earliest recorded commercial exploitation began during 1929. Shells are important to these islands because some like Turbo, Trochus & Nautilus etc. are being used as novelties supporting many cottage industries producing a wide range of decorative items & ornaments. Shells such as Giant clam, Green mussel and Oyster support edible shellfishery, a few like Scallop, Clam and Cockle are burnt in kiln to produce edible lime. The Univalve or one shell group belongs to the class Gastropoda having more than 80,000 species. Sacred Chank belongs to this group. Their body, in the course of development, go through a complicated process, 'torsion' i.e. the visceral mass is twisted though 90 degree together with the shell that covers it. Under mysterious circumstances many a time this process proceeds in the reverse direction thus creating an abnormal shell which otherwise lives like a normal shell. A classic example is the most wanted left-handed chank. The Bivalve or Pelecypoda has about 20,000 living species. Majority of then burrows in sand or mud such as Pearl Oyster, Wing oyster, Giant clam etc. A third group, which is comparatively smaller, is called Cephalopoda, which includes Octopus, Squid, Nautilus etc. The soft body animal, which lives inside the shell, is covered with a thick layer of specialised epithelium cells known as rnantle, which in turn secretes a two tier shell material making the shell. The outer layer having a different colour pattern is organic in constitution, technically called 'periostracum'. Calcium ions from the environment are absorbed into the blood and deposited evenly under this layer. The next inner layer is called 'nacre' or 'mother of pearl' responsible for the pearly lustre common to many shells.

CORALS

Corals belong to a large group of animals known as Coelenterata (stinging animals) or Cnidaria (thread animals). Corals grow slow, they have type wise site specific growth rates. The massive forms may grow upto 2 cm. in diameter and upto 1 cm in height a year, whereas, delicate branching forms grow between 5 to 10 cm. per annum. A true reef building stony coral may be unisexual or bisexual. They breed together once in a year at a pre-determined time after dusk. This process, at places is so intense that the water stays pinkish till next morning. A large number of baby corals are released in the open ocean this way. After sometime these baby corals settle over a suitable substratum and start forming new colonies through asexual reproduction. Their morphological features change with the environment in which they settle. Due to this peculiar character they are often called 'Plastic animals'. Stony corals could be broadly divided into reef builders and non-reef builders, the reef builders are called hermatypic whereas others are known as ahermatypic corals. The reef builders possess hard calcareous skeleton and need sunlight like plants to survive. On the other hand, the non-reef builders are devoid of a true stony framework and can live well without sunlight. A few among them are capable of making protein based solidified skeleton

FISHES

Each life form in the sea is confined to its own particular zone, where pressure, light, temperature and salinity are more or less constant. In this stable environment some creatures have remained unchanged throughout their entire history. The now famous Coelacanth, one of the groups of fishes thought to have been extinct for 60 million years, has remained essentially like its relatives as they appear in fossils. Fishes are the masters of water world. For more than 360 million years they have inhabited it. Today we have about 40,000 varieties of fishes known to science. They range in size from 10 mm (Philippine Gobie) to 21m. (whale shark). Some are flattened, others inflated, many spindle shaped, a few snakelike, still others are compressed depending on the environment in which they live or particular way of life.

MARINE AQUARIUM

Marine fish and animal keeping still has a certain mystique attached to it. This is one of the most complicated aspects of live stock management. The animal husbandry involved in it is mainly nurtured through water chemistry and microbiology. The tropical coral reef inhabitants are generally maintained in glass boxes known to us as marine aquariums. These animals turn 'fragile' under captive atmosphere because the natural system to which they belong is so heterogeneous, complex and dynamic with every tide bringing in a different condition that is so difficult to create artificially. However, since May l853 when the first tropical marine aquarium was made public in London, much has been understood and we are now able to practice a system where these animals are acclimatized and taught to be happy in their new environs.

Parasitic plants

Septemeranthus

Shiv Sahay Singh, Jan 30, 2022: The Hindu

Septemeranthus
From: Shiv Sahay Singh, Jan 30, 2022: The Hindu

New genus of parasitic flowering plant discovered from Nicobar Islands

Septemeranthus partially depends on its host but also has leaves capable of photosynthesis

A new genus of a parasitic flowering plant has recently been discovered from the Nicobar group of islands. The genusSeptemeranthusgrows on the plant species Horsfieldia glabra(Blume) Warb. The parasitic flowering plants have a modified root structure spread on the stem of the tree and are anchored inside the bark of the host tree.

The plant was found on the periphery of the tropical forest in one of the biodiversity hotspots referred to as the Nicobar group of islands separated from the Andaman group of Islands by a wide gap of 160 km with heavy tidal flows.

Heart-shaped leaves

The genusSeptemeranthushas a distinct vegetative morphology, inflorescence architecture and floral characters.The leaves of the plant are heart-shaped with a very long tip and the ovary,fruit and seeds are ‘urceolate’ (earthen pot-shaped). The flowers have five persistent bracts having conspicuous margins. The name Septemeranthusis derived from the Latin word ‘septem’ meaning ‘seven’, referring to the arrangement of flowers.The details of the discovery were published in theJournal of Botanical Taxonomy and Geobotany Feddes Repertorium.The genus belongs to the family Loranthaceae, a hemi-parasite under the sandalwood order Santalales and is of widespread importance. Plants which are hemi-parasites are partially dependent on their host plants for nutrition.For instance, the newly discovered plant that derives nutrients from its hosts has green leaves capable of photosynthesis.Loranthaceae is currently represented by nine genera and are found all across the country.What makes the new genus unique is that it is endemic only to the Nicobar group of islands. Lal Ji Singh, Joint Director, Botanical Survey of India, who has discovered the genus, said, “During field studies, I found the birds consume viscous seeds of this new genus and seeds have potential of pseudo viviparous germination that deposit on the leaves and branches of their same plant which is already attached to host plants. After germination, the life cycle of the genus starts all over again.”

Hemi-parasites include are commonly referred to as mistletoes that contain 18 families, 160 genera and over 2,200 species.They need a host tree or shrub in order to thrive and exhibit a worldwide distribution in tropical as well as temperate habitats that evolved approximately five times in the order and are important in forest ecology, pathology and medicine. They play an important role as they provide food for frugivorous birds.In addition to Septemeranthus,four other genera on non-parasitic plants, Nicobariodendron(Hippocrateaceae),Pseudodiplospora (Rubiaceae),Pubistylis(Rubiaceae),Sphyranthera, (Euphorbiaceae) have also been discovered earlier from Nicobar group of islands, highlighting the ecological significance of the region. Recently a new species in the hemiparasitic family Loranthaceae,Dendrophthoe laljiihave also been discovered from the Nicobar group of islands.

See also

Andaman And Nicobar Islands

Andaman And Nicobar Islands: Fauna

Andaman And Nicobar Islands: Flora

Andaman And Nicobar Islands: Natural calamities

Andaman and Nicobar Islands: Parliamentary elections

Andaman and Nicobar Islands: Tribes

Census India 1931: The Population Problem in Andaman and Nicobar Islands