Question

Identify the animal (A) and name the phylum to which it belongs (B).

A

a. A - Balanoglossus, B - Hemichordata
b. A - Balanoglossus, B - Cephalochordata
c. A - Nereis, B - Urochordata
d. A - Nereis, B - Annelida

Answer 1

Hint: The given diagram is elongated, symmetrical, bilaterally symmetrical and richly ciliated. This body looks unsegmented and divided into three regions: Proboscis, collar and trunk. These all features belong from hemichordates.

Complete answer:
As we can see in the diagram, the animal is elongated, symmetrical, bilaterally symmetrical and richly ciliated. There is no segment on the body and the body is divided into three regions: Proboscis, collar and trunk.

> So, our first option is A - Balanoglossus, B -Hemichordata. Balanoglossus is an ocean-dwelling acorn worm. It resembles an earthworm. Its body is long like a worm like, it is cylindrical. The body of Balanoglossus is composed of an anterior part proboscis, a collar and a long trunk and it belongs to phylum hemichordata.

> The 2nd option is A - Balanoglossus, B - Cephalochordata. As we already mentioned, Balanoglossus belongs to the phylum hemichordata.

> The 3rd option is A - Nereis, B - Urochordata. The body of Nereis is dorsoventrally flat, which is segmented and having 80 to 120 segments and divided into acorn, trunk and pygidium. It belongs to the phylum annelida.

> The last option is A - Nereis, B - Annelids. As we already mentioned about Nereis, which have a segmented body. So, the given diagram is of Balanoglossus, which belongs to the phylum Hemichordata.

Hence, the correct answer is option (A), A-Balanoglossus, B-Hemichordata.

Note: The length of Balanoglossus is 3 cm to 2 meter. Different species of Balanoglossus will show different colors. They are light brown or yellow or light red in colour. Balanoglossus is also called the connecting link between chordates and non - chordata.