Question

The adult tunicates show
A. All the chordate character
B. No chordate characters
C. Some of the chordate characters
D. Only dorsal nerve cord

Answer 1

Hint: Tunicates are the Urochordates. They are found in marine water. In the larva stage all the chordate characters are present in tunicates. Adult tunicates lack a notochord and post-anal tail. They reproduce asexually.

Complete answer:
Chordates are the animals classified into phylum chordata. The characteristics of the chordates are given as follows: They bear a notochord, a dorsal hollow nerve cord, Pharyngeal slits, Post-anal tail, organ system organization, diploblastic/trpiloblatic organization, bilateral symmetry, coelomate, unsegmented body and they also have closed circulatory system.
Tunicates belong to the phylum Urochordata. It includes around 3,000 species. They are present in shallow marine water. They were named tunicates as they have thick extracellular body covering. They are present in shallow marine water. Larvae of tunicates consists all four of the major distinguishing characteristics that are: post-anal tail, a notochord, and pharyngeal slits. Larval stage is active and mobile.
Adult tunicates are considered as craniate chordates. They do not have notochord and post-anal tail. Adult tunicates do not bear much resemblance to other chordates. They are sessile filter feeders. Body segmentation in these chordates is absent. Adult tunicate have two large openings called as siphons. These are generally hermaphrodites that sexually reproduce by cross fertilization. Individual does not have its own sperm. They can also undergo asexual reproduction by the process of budding. Indirect development is observed in tunicates.
Adult tunicates lack the most important chordate character that is notochord and post-anal tail but they maintain the pharyngeal slits. So, we can say that adult tunicates consist of some chordate characters.

Hence, the correct answer is option (C).

Note: The circulatory system of tunicates involves small pockets that are known as sinuses. Tunicates play an important role in the evolution of vertebrates. The heart does not use blood vessels, the heart pumps blood through sinuses. Direction of pumping blood into the heart can also change periodically. Urochordates contain many classes in which class Ascidiacea. It is the largest class. Examples of tunicates are: salps, larvaceans, doliolids and pyrosomes.