Hemolymph

Hemolymph (or haemolymph) is the blood analogue used by those animals, such as all arthropods and most mollusks, that have an open circulatory system. In these animals there is no distinction between blood and interstitial fluid. The liquid fills all of the interior (hemocoel) of the body and surrounds all cellss.

Hemolymph is composed of water, inorganic salts (mostly Na, Cl, K, Mg, and Ca), and organic compounds (mostly carbohydrates, proteins, and lipids).

There are free-floating cells, the hemocytes, within the hemolymph. They play a role in the arthropod immune system.