Question

Closed circulatory system occurs in which of the following organisms?
A. Snail
B. Cockroach
C. Cuttlefish
D. All of the above

Answer 1

Hint:-A class of the phylum Mollusca that includes active predatory organisms. Circulatory fluid and the interstitial fluid in these organisms are distinct. These organisms do not have an open circulatory system.

 Complete step-by-step solution:-
When the blood bathes tissues of the organisms directly, the circulatory system is said to be of open type. It is the characteristic feature of arthropods and most of the mollusks.
Blood in these organisms is called hemolymph. The heart pumps hemolymph which eventually flows into the large spaces called sinuses. The network of sinuses makes the hemocoel, the cavity. Blood is in direct contact with tissues in the sinuses. Snail (a mollusc) and cockroach (an arthropod) have an open circulatory system.
The phylum Mollusca includes four classes: Polyplacophora, gastropods, Bivalvia, and Cephalopoda. Cephalopods are mostly marine mollusks. They are active predators and have closed circulatory systems. When the blood flows through a network of blood vessels, the circulatory system is said to be of closed type. It is the characteristic feature of annelids, vertebrates, and cephalopods.
Blood in cephalopods flows into a series of blood vessels and does not bath the tissues. Cuttlefish belongs to the order Sepioidea of the class Cephalopoda of the phylum Mollusca. Therefore, despite being a mollusc, it has a closed circulatory system.
So, the correct answer is option C. Cuttlefish.

Note:- Squids and octopus are other examples of cephalopods. Blood in cuttlefish is blue-green due to the excess of the copper content in the hemocyanin. Hemocyanin is the oxygen carrier protein in these organisms.