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Ascaris is characterized by :
A
presence of true coelom but absence of metamerism
B
presence of true coelom and metamerism (metamerisation)
C
absence of true coelom but presence of metamerism
D
presence of neither true coelom nor metamerism
Detailed Solution
Ascaris (the roundworm) belongs to the phylum Aschelminthes (Nematoda).
Aschelminthes are pseudocoelomates: the body cavity is not lined by mesoderm; instead the mesoderm is present as scattered pouches between the ectoderm and endoderm. So a true coelom is absent.
The body is long, cylindrical and circular in cross-section, and it is unsegmented, so metamerism is also absent.
They have the organ-system level of organisation, bilateral symmetry and a complete alimentary canal with a well-developed muscular pharynx.
A true coelom together with metamerism is found in annelids, not in roundworms.
So Ascaris is characterised by the presence of neither a true coelom nor metamerism.
Aschelminthes are pseudocoelomates: the body cavity is not lined by mesoderm; instead the mesoderm is present as scattered pouches between the ectoderm and endoderm. So a true coelom is absent.
The body is long, cylindrical and circular in cross-section, and it is unsegmented, so metamerism is also absent.
They have the organ-system level of organisation, bilateral symmetry and a complete alimentary canal with a well-developed muscular pharynx.
A true coelom together with metamerism is found in annelids, not in roundworms.
So Ascaris is characterised by the presence of neither a true coelom nor metamerism.