Question

Which of the following animals is Protochordata?
A. Herdmania
B. Balanoglossus
C. Branchiostoma
D. Both A and C

Answer 1

Hint: Protochordata (Gr.protos means first) is small, marine organisms that belong to lower or primitive chordates. These are exclusively marine. Urochordata and Cephalochordata are referred to as Protochordata.

Complete answer:
Animals belongs to phylum Chordata that can be characterized by following fundamental properties
-Presence of notochord
-Paired pharyngeal gill slits
-Dorsal hollow nerve cord.

Phylum Chordata are divided into three subphylums that show above mentioned characteristics at certain periods or for entire periods in their lifetime. It is divided into subphylum - Urochordata (or Tunicata), Cephalochordata and Vertebrata. Subphylum Urochordata and Cephalochordata are considered as Protochordata. It also includes phylum Hemichordata.

Characteristics of Phylum Protochordata-
-Completely marine in nature.
-Notochord is either present throughout the lives or only during the early embryonic stage.
-Bodies are triploblastic and shows bilateral symmetry
-Post anal tail help in movement
-The gut is ventral to the nerve cord.
-Ventral heart and closed circulatory system.

Classification of Phylum Protochordata-
-Urochordata or Tunicata- It is a marine organism mostly sessile in nature resembles a worm. Notochord is present only in the larval stage. Breath by using gills.Open type of circulatory system and reproduce asexually by budding. Examples- Salpa, Ascidia, Herdmania
-Cephalochordata- It is also marine. Notochord is present throughout life and extends from head to tail.
It can move by the tail. Examples- Branchiostoma (Amphioxus)
-Hemichordata- Marine organisms show triploblastic and bilateral symmetry.

Hence, the correct answer is option (C).

Note: Protochordates are primitive chordates that have more or less characters shown resemblance with Chordates but mostly in early or larval stage. Phylum protochordata is divided into subphylum - Urochordata (or Tunicata), Cephalochordata and Vertebrata.