Members of which phylum lack a well-defined circulatory system and respiratory system?

Question

Members of which phylum lack a well-defined circulatory system and respiratory system? (A) Aschelminthes (B) Annelida (C) Arthropoda (D) Hemichordata

Tardigrade Admin · Accepted Answer

The circulatory system was seen for the first time in phylum Annelida and shows a closed type of circulatory system, while Arthropoda and hemichordate shows an open type of circulatory system. In phylum Aschelminthes (Nemathelminthes) the circulatory system and respiratory system are absent.

Q. Members of which phylum lack a well-defined circulatory system and respiratory system?

Aschelminthes

Annelida

Arthropoda

Hemichordata

The circulatory system was seen for the first time in phylum Annelida and shows a closed type of circulatory system, while Arthropoda and hemichordate shows an open type of circulatory system. In phylum Aschelminthes (Nemathelminthes) the circulatory system and respiratory system are absent.