Animal World

Arthropods: Crustaceans, Insects, and Spiders

Why do some biologists consider the insects the most successful group of animals?

With more than one million described species (and perhaps millions more not yet identified), class Insecta is the most successful group of animals on Earth in terms of diversity, geographic distribution, number of species, and number of individuals. More species of insects have been identified than of all other groups of animals combined. What insects lack in size, they make up for in sheer numbers. If we could weigh all the insects in the world, their weight would exceed that of all the remaining terrestrial animals. About 200 million insects are alive at any one time for each human.


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