Answer:
I'm not entirely sure, does the question have awnswes to choose from, if so I would say the transition is like a new birth from bam to bam. sorry if this is wrong pal.
Answer:
What is your chosen ecosystem?
Explanation:
Cnidaria - incomplete digestion [have only a single opening] ,digestion is extracellular and intracellular ,they have stinging casules called cnidoblast which helps for anchorage,defence and capture prey.
echinodermata - complete digestion[mouth on ventral,anus on dorsal],have water vascular system helps in locomotion ,capture of prey,transport of food....digestion is intracellular
I am tempted to say that the nervous system processes the stimuli, or to be more specific, the neurons that go across our nervous system.