Invertebrates probably form the largest group of species in the world. About six per cent of the world's invertebrates are found in India. Molluscs include snails, slugs, squids, shellfish and octopus. Crabs, woodlice, krill are all crustaceans. Echinoderms that include starfish and sea urchins are prominent species in the oceans. Roundworms and flatworms also occur in large numbers in several habitats. Insects belonging to the phylum Arthropoda are unquestionably the most numerous. There are about 1,000,000 insects for each of the earth's six billion humans, and if all the insects of the world were weighed together, they would be 12 times as heavy as the entire human race!

Click here to download the checklist of invertebrates in India.