Do Insects have blood?
Insects don’t technically have blood, no. True blood contains cells that house respiratory pigment proteins (such as hemoglobin) involved in oxygen transport. Furthermore, true blood is completely enclosed within a circulatory system. Insects have neither a closed circulatory system, nor pigment-bearing blood cells. Insects do, however, possess a functionally equivalent fluid called hemolymph. This fluid is involved in the circulation of nutrients to the rest of the body, just like blood. Rather than being completely confined to blood vessels, hemolymph is pumped through the body cavity, where it simply bathes the surrounding tissues before being returned to the heart. In other arthropods, hemolymph also performs the role of oxygen transport, but the respiratory pigments (usually hemocyanin instead of hemoglobin) float freely in the hemolymph, rather than being confined to specialized cells. This doesn’t occur in insects because they have a completely separate tracheal system for respi
Some of them have blood, some have hemolymph. Qoute from “Insects – An outline in entomology – p.63 “Hemolymph is a watery fluid containing ions, molecules, and cells. It is often clear and colorless but may be variously pigmented yellow, green, or blue, or rarely, in the immature stages of a few aquatic and endoparasitic flies, red owing to the presence of hemoglobin.
