Category: Invertebrates
This family of polychaete worms contains about 500 mostly marine species. They can be found in all water depths – hiding under rocks, burrowing through mud, and foraging in seaweeds. They are generally omnivores but some species are actively carnivorous. When reproducing, ragworms morph into a new form known as an “epitoke” during which their digestive system may degenerate and all energy is diverted to reproduction – it dies after reproduction. This “epitoke” stage was once thought to be a different species.
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!
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Discover Animals is a web-based educational resource offered by the NAIA
