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Chapter 33 0 Invertebrates
While sampling marine plankton, a student encounters large numbers of eggs in her samples. She rears some of the eggs in the laboratory for further study and finds that the blastopore becomes the mouth in a complete digestive system. The embryo develops into a trochophore larva and eventually has a coelom and open circulation. These eggs belonged to a(n) • annelid. • echinoderm. • mollusk. • nemertean. • arthropod.
A species of terrestrial animal is discovered with the following characteristics: exoskeleton; tracheal system for gas exchange; modified segmentation. A knowledgeable zoologist would predict that its adults probably also would have * • eight legs. • a water vascular system. • a sessile lifestyle. • wings. • parapodia.
Below is a proposed phylogeny for major clades of the animal kingdom, with several of the lineages labeled (A-E). Responses may be used once, more than once, or not at all. The ancestors of which clades possessed a true coelom? A and B only C and D only C, D, and E B, C, D, and E all of these
Which clade(s) possess(es) species whose members display at least some degree of segmentation? • A only • B only • C and D • C, D, and E • all of these