| | Introduction to Animal Evolution (Site not responding. Last check: 2007-11-01) |
 | | Note that in addition to this tube-within-a-tube, both the pseudocoelomates and coelomates, but not the acoelomates, possess some form of a vascular system that serves to transport nutrients |
 | | radiata and the acoelomates) possess a single opening into their digestive cavity, one that serves as both a mouth and an anus |
 | | Soft-bodied fauna probably dates back as far as 700 million years ago, but are thought to have consisted of animals possessing no more sophistication than the acoelomates |
| www.mansfield.ohio-state.edu /~sabedon/campbl32.htm (1075 words) |