Chapter 27, Problem 16A

Summary Introduction

To write:The animals have features of chordates, but do not have backbones are the close relatives of chordates.

Introduction:Echinoderms are deuterostomes which represent a significant transition in animal phylogeny. Echinoderms are aquatic mammals, and are the only species to have a deuterosome development and an endoskeleton in evolutionary history.

Explanation of Solution

Invertebrate chordates, which refer to two of the chordate subphyla − Cephalochordata and Urochordata, have a dorsal tubular nerve cord, pharyngeal pouches, a notochord, a postanal tail, and possibly ancestral thyroid glands. They do not have any backbone.

Conclusion

Thus, it concludes thatcephalochordata and urochordata have chordate features, but the close relatives of chordates do not have backbones.