blood in vertabrates and invertabrates

In vertebrates, the circulating fluid, or blood is kept within a closed circulating system, whereas hemolymph is the circulating fluid of animals with open circulatory system, for example insect.
The coelomic fluid of some invertebrates also has a circulatorry role instead of blood.
The function of blood.
Respiratory pigments in blood.
Transport of nutrients
Circulate hormones
Blood clotting
─░mmune reponses
Phagocytosis of dead cells and foreign materials
─░mportant pH buffer system
Constituents of blood can confer antifreeze properties.
Heat exchange
Blood volume is 6% in cephalopod mollusks, 3-16% in vertebrates, and 30% or more in arthropods.
In animals having open circulatory system, the blood volume is only a fraction of the extracellular fluid volume but blood volume is only a fraction of the extracellular volume for animals with a closed circulatory system.
Hematocrit value
Plasma volume, cell volume