DENDROLOGY

Detailed explanation-1: -invertebrate, any animal that lacks a vertebral column, or backbone, in contrast to the cartilaginous or bony vertebrates. More than 90 percent of all living animal species are invertebrates.

Detailed explanation-2: -5 % of animal species are vertebrates. Flatworms, arthropods, sponges, insects are a few examples of Invertebrates. Mammals, fish, reptiles, amphibians, and birds are examples of Vertebrates.

Detailed explanation-3: -Invertebrates are those organisms that lack a spine or back bone. They evolved before vertebrates and are generally a simpler form of life having a simple notochord or simple nervous system. The support and structure that comes from the backbone come from other structures in invertebrates.