What kind of blood do insects have?

Insects possess a fluid known as hemolymph, which is functionally similar to blood in vertebrates but has distinct differences in coloration and composition. Hemolymph is typically transparent or slightly yellowish and does not contain red blood cells as found in vertebrates, which is the reason it does not appear red or colored like traditional blood. Instead, hemolymph serves a variety of functions, including transporting nutrients, hormones, and waste products, as well as playing a key role in the insect's immune defense.

This characteristic of being transparent is significant because it reflects the unique physiological adaptations of insects compared to other organisms. Additionally, while the terms oxygenated and deoxygenated blood relate to vertebrate blood and its role in respiratory gas exchange, hemolymph operates differently by bathing the organs directly in a fluid that is not specialized for oxygen transport in the same way. The notion of hemolymph being colored is also misleading since the absence of red blood cells means it does not take on colors associated with oxygenated or deoxygenated states.