LATEST RELEASE FROM THE SHAPE OF LIFE BOOK. The Next Segment - An Explosion of Life
"What I like doing the most is actually getting out, getting down, getting dirty in the mud with the worms themselves. Getting out there whether it’s pouring rain, whether it’s a low tide at dawn, I don’t care. I just like to be out there with the worms, seeing them in their own habitat."
DAMNHAIT MCHUGH, BIOLOGIST
All annelids are distinguished by ringlike external bands that coincide with internal partitions dividing the body into segments, each containing a repetition of nerves, muscles, and reproductive organs. With circulatory systems to distribute blood and oxygen and one-way guts, their bodies are enormously more complex than modern flatworms. A gut that goes from one end of the body to the other was a major step in the evolution of animals. With such a gut, food can be continuously taken in by a mouth, processed as it passes through the body and released as waste at the other end. Not only could the early annelids continually digest their food, but also they could squirm, crawl and slither as they did it, thus not interrupting their movement whether hunting or fleeing.
A substantial body against which muscles could work to produce powerful movements was a great architectural breakthrough. The secret of the success of these new bodies was an internal cavity that not only provided room for large complex organ systems, but also proved essential for more complex ways of living.
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