Chapter 34, Problem 1IQ

Name the animal shown in the following diagram and indicate the chordate group to which it belongs. Identify the labeled structures and indicate the four chordate characters.

Summary Introduction

To name: The animals shown in the given diagram, indicate the chordate group to which it belongs, identify the labelled structure, and indicate the four characters of chordate.

Introduction: Deuterostomia is a sub taxon of Bilaterians. It includes chordates and echinoderms. A chordate is an animal belongs to the phylum Chordata. Chordates include urochordates, cephalochordates, and vertebrates.

Answer to Problem 1IQ

Pictorial representation: Fig.1 shows the labeled structure of lancelet and four characters of chordate.

Fig.1: Labeled structure of lancelet and four chordate characters

Explanation of Solution

The animal shown in the given (Fig.1) is lancelet and it belongs to the chordate group of Cephalochordata.

Lancelets are marine animal, which is tiny in nature. It retains complete four characteristics of chordate into the stage of adult. The adult lancelet, which is involved in suspension-feeding burrow backward to the soil and particles of food are filtered by a mucous net, which is produced across the pharyngeal slits. Using serial muscle contractions, the lancelet swims. The notochord is flex by these serial muscle contractions. From the mesoderm, these segments of muscle mature and it is called somites. It is found in all embryos of chordate.

Four chordate characters: In Fig.1, the symbol * indicates the derived characters of chordates. It includes notochord, dorsal, hollow nerve cord, pharyngeal slits, and a post-anal tail.

Notochord: It is a flexible chord and it gives skeletal support beside a length of embryos of chordate and in certain chordate adult.

Dorsal, hollow nerve: It develops into the spinal cord and the brain.

Pharyngeal slits: The pharyngeal grooves or clefts frequently develop into pharyngeal slits. The role of the pharyngeal slit is involved in suspension feeding or portion of head or function as gills.

A muscular, post-anal tail: It contains muscles and skeletal elements.