In a reverse hierarchy, the conceptual pyramid of authority is turned upside-down, so that the apex is at the bottom and the base is at the top. This model represents the idea that members of the higher rankings are responsible for the members of the lower rankings.
Along the sides of the body is a light-colored horizontal stripe called the lateral line. The line is made up of a series of tiny pores that lead to receptors that are sensitive to the mechanical movement of water and sudden changes of pressure.The spiny dogfish has a double dorsal fin.The anterior dorsal fin is larger than the posterior dorsal fin.The spiny dogfish has the presence two spines, one immediately in front of each dorsal fin. The spines carry a poison secreted by glands at their base.he spiny dogfish has a double dorsal fin. The anterior dorsal fin is larger than the posterior dorsal fin. The spiny dogfish has the presence two spines, one immediately in front of each dorsal fin. The spines carry a poison secreted by glands at their base.
1 Both sharks and bony fish have caudal fins, or tail fins with two lobes. 2  The caudal fin of a shark is considered heterocercal, meaning the two lobes are unequal in size and the vertebral column extends up into the top lobe. The skull of a shark is made of only 10 cartilaginous elements while a bony fish skull has about 63 bones. 2  Bony fish have pleural ribs formed from dermal bone and sharks lack these ribs. 3  Unlike bony fish that have a protective bony plate covering their vulnerable gills, the gill slits of a shark are exposed and visible.