What is an example from the animal world were a living system is sensitivity into a weak field

Sensory systems provide information from outside the animal that, when integrated, shape behavior. Internal senses, such as hunger or fear, affect behavioral priorities. Motivation describes how animals make choices among possible behaviors, based on the strength of internal needs and sensory inputs.

Because they are stupid and insensitive

Centriole.centrioles are present in animal cells but are usually absent in plant cells.