Category: Invertebrates
These tube shaped, segmented worms commonly live in the soil and feed on both live and dead organic matter. Earthworms are hermaphrodites, meaning they have both male and female reproductive organs. There are over 6000 named species of earthworms, ranging in size from less than half an inch to over nine feet long! Earthworms have no doubt played a keystone role in human agriculture, as their activity aerates the soil and mixes in organic material, creating conditions favorable for plant growth.
The world’s first Animals
Invertebrates were the first animals to evolve. While their soft bodies left precious few records behind, there are fossils of sponge-like animals that are 665 million years old, as well as traces of tracks and burros from worm-like animals going back 1 billion years. By comparison, the earliest birds appeared only 150 million years ago! And not only were invertebrates first, they are the most plentiful of animals - it is estimated that 97% of all animals living on the Earth today are invertebrates, with several groups containing more species than all vertebrates combined!
Learn more >>
Discover Animals is a web-based educational resource offered by the NAIA
