Question

Balanoglossus is now classified in.
A. Chordata
B. Urochordata
C. Cephalochordata
D. Non-Chordata

Answer 1

Hint: Animals in phylum Chordata have “notochord, dorsal hollow nerve cord, closed circulatory system and paired pharyngeal gill slits''. Non-chordate animals have a “worm-like cylindrical body with open circulatory system”. Urochordata and Cephalochordata are classified under phylum Chordata.

Complete Answer:
Let us find the correct answer,
Option A: Balanoglossus does not contain notochord, dorsal central nervous system, perforated pharyngeal gill slits, ventral heart, postnatal tail, and closed circulatory system in its body (main characteristics of phylum Chordata). Hence option A is incorrect.

Option B: As Urochordata are classified under phylum Chordata so, if it is not a chordate it can not belong to Urochordata. Hence option B is incorrect.

Option C: As Cephalochordata also classified under phylum Chordata so, if it is not a chordate it can not belong to Cephalochordata. Hence option C is incorrect.

Option D: If we divide the balanoglossus body in different parts it is composed of the proboscis, collar, and long trunk and also contains an open circulatory system with worm-like body structure similar to animals in Non-Chordata. Hence option D is correct.

Thus, the correct option is Non-Chordata (option D).

Additional information: Previously balanoglossus was classified under phylum Hemichordata which was considered as the subphylum under Chordata. But now Hemichordata is considered as a separate phylum under Non-Chordata.

Note: Chordates have metamerically segmented bodies, this is clearly shown by muscular, nervous, circulatory, and excretory systems, whereas these segmentation are absent in Non-Chordates.