NEET BIOLOGY

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: -Invertebrates are animals without a backbone or bony skeleton. They range in size from microscopic mites and almost invisible flies to giant squid with soccer-ball-size eyes. This is by far the largest group in the animal kingdom: 97 percent of all animals are invertebrates.

Detailed explanation-3: -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-4: -Invertebrates have no bones. True. Instead, many invertebrates are supported by exoskeletons, while those that live in the sea are often supported by a fluid–filled cavity surrounded by muscles. This is called a hydrostatic skeleton.

Detailed explanation-5: -An invertebrate is an animal without a backbone. In fact, invertebrates don’t have any any bones at all! Invertebrates that you may be familiar with include spiders, worms, snails, lobsters, crabs and insects like butterflies. However, humans and other animals with backbones are vertebrates.