Porifera is an extant phylum within the animal kingdom, and species belonging to this phylum do not have nervous systems. Although Porifera do not form synapses and myofibrils which allow for neuromuscular transmission, they do differentiate a proto-neuronal system and contain homologs of several genes found in Cnidaria which are important in nerve formation.[1] Sponge cells have the ability to communicate with each other via calcium signaling or by other means.[2] Sponge larvae differentiate sensory cells which respond to stimuli including light, gravity, and water movement, all of which increase the fitness of the organism. In addition to sensory cells differentiated during development, adult Porifera display contractile activity.[3]