Not all forms of animal or insect life have red blood. A notable exception is the spider. Spiders have blood that appears to be a somewhat blue or blue-green variety. This is because the oxygen in a spider's bloodstream is not bound to hemoglobin, as is the case with humans. Instead, the oxygen is bound to hemocyanin, which contains copper rather than the iron that is found in hemoglobin. The result is a blood color that is blue rather than red.
More facts about animal blood:
- Not all living things contain blood. Invertebrates such as flat worms and jelly fish do not rely on blood to distribute nutrition though the body. These animals without backbones are capable of absorbing nutrients through the skin and eliminating waste in a similar manner.
- There are several variations of blood color in different types of animals. Crabs and lobsters have blue blood, and leeches and earthworms have green blood. There also are invertebrates, such as starfish, that have yellow blood.
- Giraffes tend to have the highest average blood pressure when compared to other types of wild and domestic animals.