Hello, I'm an expert in the field of biology with a focus on zoology. Let's dive into the question of whether worms have blood.

Worms, which belong to the phylum Annelida, do have a circulatory system, but it's quite different from the one found in mammals. Most worms have a system of fluid-filled spaces called coelom, which serve as a hydrostatic skeleton and also help in the transportation of nutrients and waste. However, some worms do have a true circulatory system with a heart or hearts and blood vessels. The "blood" in these worms, known as coelomic fluid, serves a similar purpose to blood in other animals, carrying nutrients and oxygen to the cells and removing waste products.

In earthworms, for example, the coelomic fluid is a colorless liquid that contains cells such as amoebocytes and leukocytes, which are involved in immune responses. It also transports nutrients and waste products. The coelomic fluid is not red like human blood because it does not contain hemoglobin, the protein that gives blood its red color due to its ability to carry oxygen.

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The ventral blood vessels are responsible for carrying blood to the back of the earthworm's body. Earthworms do not have lungs. They breathe through their skin. Oxygen and carbon dioxide pass through the earthworm's skin by diffusion.read more >>