The mucus traps the particulate matter drawn into the pharynx and is swallowed in a continuous stream. This is effective but rather a slow process and there must be dense concentrations of food to have any effect. After emerging from the mud metamorphosis and migration to a lake or out to sea takes place. Lampreys most distinctive feature the oral disc, filled with numerous toothlike plates of keratin that cover the disc and tongue in speciesspecific patterns is put into action. An adult predatory lamprey latches onto the side of a fish and after rasping a hole begins sucking their blood and other body juices.
Lampreys reach up to a length of four feet and as small as five inches.
The lamprey feeds on other fish by secreting a chemical called lamphredin, which prevents the victim s blood from clotting. The head of an adult lamprey has relatively large eyes, followed posteriori by a series of seven, rounded gill openings. The brain has a poorly developed cerebellum but large optic lobes. Remarkably these fish have been seen going over vertical walls up to six feet high. Eel morphology is rather constant throughout all of the Anguilliformes.