Biology (11th Edition)

Published by McGraw-Hill Education
ISBN 10: 1-25918-813-2
ISBN 13: 978-1-25918-813-8

Chapter 34 - Protostomes - Review Questions - Synthesize: 4


No, especially since it is a parasite, parasites often being highly specialized. Further, having a digestive tract is seen in animals below the Platyhelminthes in fig. 35.5, so it is more likely that the digestive tract has been lost in this case.

Work Step by Step

The key here is to look lower down the phylogenetic tree. Since the digestive tract is seen lower on the tree, any absence higher up is probably due to loss rather than to retention of an ancestral character state.
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