EVERYDAY SCIENCE

Detailed explanation-1: -The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike central nervous systems, where neurons are typically grouped together, neurons found in nerve nets are spread apart. This nervous system allows cnidarians to respond to physical contact.

Detailed explanation-2: -Although cnidarians are essentially floating nerve nets, with no true brains, they possess ganglia to coordinate nerve messages along the body. Cnidarians lack specific response to external stimuli, such as detecting what direction a stimulus is coming from.

Detailed explanation-3: -Cnidarians are considered “nerve net animals” even though their nervous systems include various forms of condensation and centralization. Yet, their broad, two-dimensional muscle sheets are innervated by diffuse nerve nets.

Detailed explanation-4: -The nerve net may be the most efficient way to innervate broad, two-dimensional sheets of effectors in which multiple, spatially-separated sites of excitation can activate the effectors.

Detailed explanation-5: -A diffuse nerve net is a basic design of cnidarian nerve systems. Nerve net of the sea anemone Nematostella vectensis revealed by expression of a mCherry protein under nerve-specific elav promotor. Modified from [98].