The Andaman Nicobar Islands tropical rain
forests despite their isolation from adjacent landmasses are surprisingly
enriched with many animals.
Out of 55 terrestrial species and 7 marine mammal species reported, 32 species are endemic. Most of these mammals 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. Common mammal found over here are Andaman Wild Pig, Crab Eating Macaque. Andaman Masked Palm Civet, Dugong, Dolphin, Whale, Spotted Deer, Andaman Spiney Shrew, Nicobar Tree Shrew, Nicobar Tree Shrew, Andaman Horse-Shoe Bat, Lesser Short Nosed Bat (Brachysoma), Elephant, etc.
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 Andaman & Nicobar 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.
AVIFAUNA & TERRESTRIAL REPTILES
The rich Avifaunal diversity has always attracted ornithologists and bird watchers to these islands. As many as 246 species and sub species of birds are reported to inhabit these islands and of these 99 species and sub-species are endemic. Some important species are Andaman Teal, Megapode, Narcondum hornbil, Nicobar pigeon, green imperial pigeon, Nicobar parakeet, crested serpent eagle, white-bellies sea eagle, Edible-Nest Swift let, Emerald Dove etc. Sandy beaches of these islands are famous for turtle nesting. There are 76 terrestrial reptiles. Of these 24 species are endemic. Important species include four main species of sea turtles viz., Leatherback Turtle, Green Sea Turtle, Hawk Bill Turtle and Olive Ridley turtle, Salt Water crocodile, Water Monitor Lizard, Reticulate Python, Sea Snakes and many other varieties of snakes including King Cobra are also found here.
Due to its long coastal stretch, these islands have a very rich marine biodiversity. They harbour more than 1,200 species of Fish, 350 species of Echinoderms, 1,000 species of Mollusks and many more lower forms of life. Among vertebrates, Dugong, Dolphin, Whale, Salt-Water Crocodiles, Sea Turtles, Sea Snakes, etc. are common.
Corals and coral reefs are the most fascinating part of marine ecosystem here. Corals are composed of calcium carbonate, a mineral they take from seawater. The skeleton of coral forms different densities in summer and winter months, creating annual growth bands likened to that of tree rings.
Coral reefs are underwater wave resistant mounds that are virtual ecosystems all by themselves. They are made up of Coral, Algae, Mollusks, Bryozoans, Brachiopods, Echinoderms and Sponges. Coral sands and solid limestone also play a large part in the build up of a coral reef. Coral reefs grow upward by a rock like accumulation of calcium containing (Calcareous) Exoskeletons of past generations of coral animals.
In their ideal environments, coral reefs will grow from 1 to 100 centimeters per year. So far 179 species of corals belonging to 61 genera have been reported in the islands. Reefs are mostly fringing type on the eastern coast and barrier type on the western coast. Important genera include Acropora, Montipora, Policillipora,Porites,Favia, Fungia Goniopora, Millipora And Heliopora. Coral reefs are important breeding and nursery ground for fish and many other organism and have been aptly called "The Tropical Rain Forests in the Sea".