Question

Which of the following animals belongs to Urochordata?
A. Herdamania
B. Balanoglossus
C. Amphioxus
D. Petromyzon

Answer 1

Urochordata is an aquatic invertebrate animal, a member of the subphylum Tunicata. It is a division of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords. They are the solitary chordates that have lost their myomeric segmentation, with the probable exception of the seriation of the gill slits.

Complete answer:
Balanoglossus is a deuterostome, and looks like the sea squirts, in that it possesses “gill slits''. It has notochord in the higher part of the body and is devoid of nerve cord. Amphioxus includes some species of "fish-like" benthic filter feeding chordates in the order Amphioxiformes. Petromyzon marinus is a parasitic lamprey inhabitant to the Northern Hemisphere.
Herdmania is a maritime animal. They are embraced in the subphylum Urochordata. They are inactive types of animals. They are attached to the substratum or rock with the help of the flat base like organization. Whenever the organisms are agitated, they abruptly contract their body and emit inner contents with force by its apertures.
So, they are generally called sea squirt. The larvae possess retrogressive metamorphosis in which there is loss of superior features while development to adult.

Hence, the correct answer is option (A).

Note: Like other chordates, urochordates have a notochord for the period of their early growth. Notochord is lost by the time they have finished their metamorphosis. As members of the Chordata, they are right Coelomata with endoderm, ectoderm, and mesoderm, but they do not enlarge very noticeable coelomic body cavities, if any at all. In urochordates is the body wall or mantle composed of connective tissue, muscle fibres, blood vessels, and nerves.