Low blood pressure makes them resistant to certain diseases, and their blood can also clot quickly to prevent blood loss.
Water-like blood (no hemoglobin, uses seawater for circulation).
Yellow blood due to high concentration of a vanadium-based pigment.
Blue blood due to the copper-based compound, hemocyanin which aids in oxygenation.
No red blood cells; instead, they have a unique circulatory system with a high concentration of copper.
Extremely high levels of white blood cells, make their blood a potential source for antibacterial and antiviral compounds.
Blue-green blood due to copper-based hemocyanin, which is more efficient in cold, low-oxygen environments.