Question

The open circulatory system is found in –
A. Earthworm
B. Cockroach
C. Snail
D. Both B and C

Answer 1

According to the classification of the animal kingdom, Arthropoda and Mollusca have an open type of circulatory system while organisms of Annelida have a closed circulatory system.

Complete answer: In open circulatory systems, the fluid does not flow in arteries and veins, it is directly pumped into the body cavity called hemocoel. Heart may be present but it directly pumps body fluid in different body cavities. Open circulatory systems instead of blood, haemolymph is used. The functions of blood, lymph, and intestinal fluids, which are highly specialized fluids in animals with closed circulatory systems, are carried by haemolymph. Haemolymph directly absorbs nutrients from food and oxygen in the hemocoel. Open circulatory systems are less efficient than closed circulatory systems. The open circulatory system cannot provide enough supply to support a large body.
It has following functions-

Transport of oxygen to different parts of the body.
Transport of nutrients
Transport of waste materials
Acts as messenger for cells
Transport of various cells, such as immune cells.
Difference between open and closed circulatory system-

S.No	closed circulatory system	open circulatory system
1	Blood is the fluid circulated in it.	Haemolymph is present instead of blood.
2	Blood flows in closed blood vessels	Haemolymph is directly pumped into hemocoel
3	More efficient	Less efficient
4	Present in members of Vertebrata, Annelida	Present in members of arthropoda and mollusca.

Thus, the correct answer is- D. both B and C.

Note: earthworm is a member of phylum Annelida and has a closed circulatory system while snail is of Mollusca and cockroach falls under Arthropoda. Open circulatory system is a characteristic feature of Arthropoda and Mollusca, not of Annelida.