EVERYDAY SCIENCE

Detailed explanation-1: -Only five percent of all known living animal species are vertebrates or animals with backbones (Fig. 3.3). 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.

Detailed explanation-2: -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-3: -Invertebrates are animals that lack a backbone or spine. More than 90 per cent of living organisms are invertebrates, which are more varied in form than animals with backbones (vertebrates).

Detailed explanation-4: -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.