They are things your body cannot produce on it's own
These animals were living in an environment with a warm climate that results in changing sea levels. These conditions create a lot of shallow inland seas allowing these animals to thrive. The Cretaceous period is the last period of the Mesozoic area where new groups of mammals, birds, and flowering plants appeared on Earth.
Answer: if change happens naturally in an ecosystem it will be better evolved to handle it. But at the expense it happens very slowly
Explanation: my answer
Jellyfish contain 99% of water.
