How do embryos and sponges show poorly organized responses to stimuli?

In the study of stereotyped responses, unorganized or poorly organized responses are characteristic of organisms that lack a nervous system, specifically early embryos and sponges.1

These organisms exhibit poorly organized responses because they lack the specialized structures—such as neurons, nerve networks, and musculature—required to coordinate rapid, integrated reactions to environmental stimuli. While more complex animals utilize a nervous system to conduct impulses from sensory receptors to effectors, sponges and early embryos do not possess these integrative mechanisms. Consequently, they do not display the conspicuous, directed movements or complex behavioral patterns seen in organisms with more developed nervous systems.213