Do all animals have blood?

Question

Do all animals have blood?

Answer

Many invertebrate animals such as coral, jelly fish and flat worms do not have blood because they are able to absorb nutrients and move gases and wastes directly to the outside of their bodies. Blood comes in other colors. Earthworms, leeches, and insects have green blood.

Source: google

Why did this come up

Watching National Geographic show on scientists collecting the blood of seals to detect pollution.