Similar to skeletal muscle tissue, cardiac muscle does not regenerate to a great extent. Dead cardiac muscle tissue is replaced by scar tissue, which cannot contract. As scar tissue accumulates, the heart loses its ability to pump because of the loss of contractile power.
Jellyfish have glowing protein as well as fireflies, corals, species of fish and certain species of frogs. Basically any animal or plant you see in nature that produces its own fluorescent light.
