Why are open circulatory systems advantageous to some animals?
- They use less metabolic energy.
- They help the animal move faster.
- They do not need a heart.
- They help large insects develop.
Some animals use diffusion instead of a circulatory system. Examples include:
- birds and jellyfish
- flatworms and arthropods
- mollusks and jellyfish
- none of the above
Blood flow that is directed through the lungs and back to the heart is called ________.
- unidirectional circulation
- gill circulation
- pulmonary circulation
- pulmocutaneous circulation