Animal WorldAnimal Characteristics and Activities |
What is the difference between an invertebrate and a vertebrate? |
Invertebrates are animals that lack a backbone. Almost all animals (99 percent) are invertebrates. Of the more than one million identified animals, only 52,000 have a vertebral column; these are referred to as vertebrates. Most biologists believe the millions of species that have yet to be discovered are exclusively invertebrates.