INVERTEBRATE ZOOLOGY : QUESTION BANK FOR NEET

It is estimated that our planet is inhabited by around 1.7 million different organisms. To our surprise, every year biologists record about 18,000 new species of both plants and animals. Interestingly, out of these 18,000 species, 13,500 are novel invertebrates. Biologists have blessed the scientific world with the discovery of 1,305,250 invertebrates thus far, and so many species are yet to be discovered and described.

These so-called invertebrates are useful in many ways. For instance, butterflies, beetles, bees, ants, dragonflies, snails etc are primary builders of a healthy environment. Similarly, the coral reefs add beauty to the oceans with their colorful appearances. 

The Animal Kingdom has categorized just over a million scientifically described species, in thirty five phyla. Phylum Arthropoda (insects, spiders, crustaceans, millipedes and centipedes among others) has an estimated 9,99,059 identified species or 85% of the total identified animal species. 

The invertebrates are named so because of the absence of back bone or vertebral column in their bodies. The animals without back bone make therefore a separate group called ‘Invertebrata.’ At present time, there are around thirty invertebrate phyla, however we deal with only 9 invertebrate phyla in class 11. Those include, phylum Porifera, phylum Cnidaria, phylum Ctenophora, phylum Platyhelminthes, phylum Aschelminthes, phylum Annelida, phylum Arthropoda, phylum Mollusca and phylum Echinodermata.