EVERYDAY SCIENCE

Detailed explanation-1: -More than 90 percent of all living animal species are invertebrates. Worldwide in distribution, they include animals as diverse as sea stars, sea urchins, earthworms, sponges, jellyfish, lobsters, crabs, insects, spiders, snails, clams, and squid.

Detailed explanation-2: -The vast majority of animal species (95 percent) are invertebrates. Among all animal species, one particular group easily claims the highest number of species: the insects. Insects-a group within the phylum Arthropoda-have evolved into several millions of species, particularly beetle insects (order Coleoptera).

Detailed explanation-3: -More than 90 per cent of living organisms are invertebrates, which are more varied in form than animals with backbones (vertebrates). Some terrestrial invertebrate forms include insects, spiders, crustaceans, round worms, molluscs, segmented worms, and flat worms.

Detailed explanation-4: -To group all invertebrates together is an immodest proposal, since the definition of “invertebrate” is any animal without a spinal column-no less than 97 percent of all animal species on Earth.

Detailed explanation-5: -Arthropods are considered the most successful animals on Earth. The phylum includes more species and more individuals than all other groups of animals combined. Over 85 percent of all known animal species are arthropods (Fig. 3.73).