Invertebrates are the most abundant creatures on Earth. In fact, according to scientists, up to 99% of all animal species are Invertebrates. They include worms, jellies, anemones, snails, crabs, insects, and spiders.
No Backbone Required
Invertebrates come in a variety of shapes and sizes. They can be found in virtually every habitat on earth, from oceans to rainforests. Some float, some swim, some fly, crawl, or wiggle, and for some, the only thing they have in common is their lack of a backbone. They play a vital role in the earth’s ecosystems, yet we rarely notice them.
Scientists divide invertebrates into about 30 different groups, or phyla. These phyla include coelenterates (jellies and anemones), echinoderms (urchins and stars), mollusks (snails and octopuses), annelids (segmented worms), and arthropods (insects, spiders, and crustaceans such as crabs). Since scientists estimate that 99% of animal species are invertebrates, that means fish, amphibians, reptiles, birds and mammals make up just a fraction of life on Earth!