Chapter 27, Problem 30A

Summary Introduction

To write: The reason why the animal in given diagram could not be an invertebrate chordate

Introduction: Chordates are species belonging to the phylum Chordata that at some stage during their development have four distinctive characteristics-a dorsal tubular nerve cord, pharyngeal pouches, a notochord and a postanal tail.

Explanation of Solution

The notochord is dominated by bone or cartilage in most vertebrates. The notochord persists in invertebrate chordates. Postanal tail reaches past the anus, in most chordates. Nonchordate tails have portions of the digestive system inside, including the anus at the end of the body. The nerve cords in nonchordates are ventral to and below the digestive system, and are strong. Chordates possess a dorsal tubular nerve cord that is dorsal to or above the digestive organs, and is a type of a tube.