Cylindrical bodied, worm-like marine animals belong to the phylum: a) Echinodermata b) Mollusca c) Coelenterata d) Hemichordata

Question:

Cylindrical bodied, worm-like marine animals belong to the phylum: 

a) Echinodermata 

b) Mollusca 

c) Coelenterata 

d) Hemichordata

Answer: option (d) "Hemichordata".

Explanation: 

Solution: (a) Characteristics of Echinodermata: They have a star-like appearance and are spherical or elongated. They are exclusively marine animals. The organisms are spiny-skinned. They exhibit organ level of organization. 

(b) characteristics of phylum Mollusca: They are mostly found in marine and freshwater. Very few are terrestrial and found in moist soil. They exhibit organ system level of organization. Their body has a cavity. The body is divided into head, visceral mass, muscular foot and mantle. 

(c) characteristics of phylum Coelenterata: These are mostly aquatic or marine habitat animals. These species exhibit a tissue-level organization. The mouth is enclosed by thin and short tentacles. They are diploblastic animals, in which, the body is made up of two layers of cells: Ectoderm - One layer makes up the cells outside the body Endoderm - the other forms the inner lining of the body.

(d) characteristics of phylum Hemichordata: Phylum Hemichordata consists of a small group of worm-like marine animals. They have organ-system level of organization, bilaterally symmetrical, triploblastic and coelomate animals. The body is cylindrical and is composed of an anterior proboscis, a collar and a long trunk. 

Hence, the correct answer is option (d) "Hemichordata".