Phylum Mollusca includes invertebrates that are found in freshwater and saltwater environments as well as terrestrial areas that are moist. They are members of the animal kingdom. Although more primitive than chordates, they possess eyes and have excellent sense organs for detecting touch, vibration and chemicals just as chordates do. They have organs like the mouth, stomach, heart, foot, anus, gonad and those are also found in chordates. Chordates include animals that possess during some point in their life cyce a notochord and a dorsal nerve cord, pharyngeal slits and a post anal tail. Chordates have a bilateral body plan. Chordates include most complex animals including those with a backbone or Vertebrates. Although chordates are more complex than mollusks, they are both in Kingdom Animalia, both possess organ systems and have well-developed nervous systems.