They have cartilaginous skeletons, no jaws, skulls that hardly differ from the rest of the vertebrae, neither pectoral fins nor ribs. Two species live on the Bank, but are very rarely seen. Due to their food habits, neither will take hooks or are rarely hauled in by nets. The sea lamprey , Petromyzon marinus is an active, voracious predator of other fish.
Sea lamprey are anadramous, running up rivers to spawn on gravel bottoms and die.
The young spend a few years in freshwater mud habitats before moving on to sea. The hagfish , Myxine glutinosa, spends long periods burrowed in clay or mud bottoms along cold water currents. Lacking external eyes, four pairs of olfactory barbels probe the currents for dead or dying fish. The tongue is modified into long pad of incurved teeth that everts to penetrate the body cavity of its food giving it access to the intestines and meat. They are rarely seen, except when they have attacked hooked or netted fish.