The respiratory system works closely with the circulatory system to deliver oxygen to the cells and rid the body of carbon dioxide. The human respiratory system includes the nasal cavity, the trachea and bronchial tree, and the primary organs, the lungs. In the animal kingdom, aquatic and terrestrial animals have different modes of respiration. Students will explore these differences, looking at the role of the water vascular system, skin, gills, and lungs in respiration. Students will look closely at and manipulate the following specimens: a starfish, a squid, a dogfish, and a mammal. They will look closely at respiratory structures.