Question

Ganesh found an organism and decided to observe its circulatory system in his lab. He found that the body tissues were in direct contact with the circulating fluid. The organism might be a/an:

• A. Annelid
• B. Chordate
• C. Arthropod
• D. Both A and C

Answer 1

The correct option is C Arthropod

There are two types of circulatory systems - open type and closed type.
In an open type circulatory system, the circulating fluid flows through the coelom. This coelom is called haemocoel. Tissues remain in direct contact with the circulatory fluid so that they can do the exchange of gases, nutrients, excretory materials etc. This type of circulatory system is observed in arthropods and non-cephalopod molluscs. So the organism found by Ganesh might be an arthropod.

In a closed type circulatory system, the blood circulates in closed vessels. So the tissues are not in direct contact with circulating fluid. The exchange of gases, nutrients, excretory materials occurs through the thin walls of closed vessels. This type of circulatory system is observed in annelids, cephalopod molluscs, chordates etc.