Answer: Circulatory system: ...
Digestive system and Excretory system: ...
Endocrine system: ...
Integumentary system / Exocrine system: ...
Immune system and lymphatic system: ...
Muscular system: ...
Nervous system: ...
Renal system and Urinary system.
Explanation:
The answer is the cell wall
For many of their illnesses scientist and doctors haven't treated them before so they don't know how to treat them or exactly if the animal can handle the treatment
