Which of the following organisms has no blood but respires?

Correct option is C

The correct answer is (c) Hydra

Explanation:
• Hydra is a microscopic freshwater organism belonging to the phylum Cnidaria. It completely lacks a specialized circulatory system or blood.
• Instead, it manages respiration strictly through simple diffusion across the cell membranes directly from the surrounding water.

Information Booster:
• Because its body wall is primarily composed of just two cellular layers (diploblastic), virtually all cells are in direct contact with the oxygen-rich aquatic environment.
• Excretion of nitrogenous waste (ammonia) in Hydra also occurs through direct cellular diffusion.

Additional Knowledge:
Cockroach (Option a)
• Cockroaches possess an open circulatory system containing a colorless fluid called hemolymph. They respire via a network of tracheal tubes.
Fish (Option b)
• Fish possess red blood filled with hemoglobin and respire aggressively through specialized gills.
Earthworm (Option d)
• Earthworms have a closed circulatory system containing red blood with dissolved hemoglobin. They respire primarily across their moist skin.
None of the above/More than one of the above (Option e)
• Incorrect, as Hydra is the classical example of this biological setup.

So the correct answer is (c)