Ichthyomyzon unicuspis

The silver lamprey (Ichthyomyzon unicuspis) is a lamprey commonly found in the Northern and Central United States, as well as a large part of southern Canada. Its binomial name means 'sucking fish' in Greek and 'one-pointed' in Latin. The silver lamprey is a member of the Class Agnatha, sometimes referred to as cyclostomes (round-mouths). Other common names include: Bloodsucker, Blue Lamprey, Hitch-hiker, Lamper, Lamprey Eel. The silver lamprey should not to be confused with the sea lamprey (Petromyzon marinus), which has caused considerable damage to native fish populations in the Great Lakes region. The silver lamprey is commonly found along the Great Lakes and in the Mississippi River and Ohio River and their tributaries from Minnesota to Nebraska, Tennessee, and West Virginia. There have also been a small number of isolated encounters around the Hudson Bay and in the Mississippi River in Mississippi. The silver lamprey is an eel-like fish with an attenuate body composed of 49–52 clearly defined segments (i.e. myomeres, between the last gill slit and the anus). Silver lampreys possess a cartilaginous skeleton, and adults generally grow to a length of 12 inches and are silvery or bluish in color when spawning. Prior to spawning adults are often a dull brown or tan color. The dorsal fin is continuous, though it may be notched. The mouth is a jawless, sucking disc, with unicuspid teeth arranged in circular rows and is in the inferior position. When expanded, the mouth is wider than the lamprey's body. The lamprey's gills are arranged in a straight line immediately behind the eye, and a single nostril is located between the eyes. Larvae are a brown to tan all over have no eyes (instead they have eyespots) and are called ammocoetes. They also have seven gill openings and do not have any paired fins, they have only a long continuous fin runs from the dorsal to the ventral side. Ammocoetes also have no teeth and instead have an oral hood which houses skin extensions that help them filter particles out of the water as they draw it into their oral cavity.