The correct terms to fill in the blanks are gastric cavity and extracellular. In cnidarians, the mouth of both the medusa and polyp form opens into an internal gastric cavity where extracellular digestion takes place. The polyp and medusa are body forms that can be found in the phylum Cnidaria. The polyp is a nonmotile body form while the medusa is a free swimming body form.
The pitch of a sound is how high or low a sound is when we hear it, whereas the intensity of a sound is the energy/vibrancy of the sound over an area and depends on the frequency of the sound as well.
