Lampreys are a fairly unique class of aquatic vertebrates with an apparently ancient lineage. Every description I’ve read identifies them as superficially similar looking to eels, but lacking a jaw and instead having a round, sucking disk mouth (Cross and Collins 1995, Wikipedia, the Great Lakes Fishery Commission, etc.). That is to say that they are elongated, have no scales, and have spine-less fins. However, the resemblance is pretty much completely superficial. In fact, lampreys are not even true fish (Cross and Collins 1995, Tree of Life), and in 2006 researchers found a fossilized lamprey that was virtually indistinguishable from the modern animal (article about the find) from 360 million years ago. That is way back there, when fish were just evolving jaws.
Lamprey life-history is fairly straightforward...for an amphibian (which it isn’t). The larvae are called ammocoetes, and live in mucky sediments consuming microorganisms (at one point, it was thought these were a totally different species). After 5-7 years of this, they grow eyes and a new mouth, get bigger and learn how to swim. Then they spent ~18 months swimming around and sucking the blood out of fish large enough for them to latch onto (this varies tremendously by species, Chestnut lampreys, the Kansas Threatened species I’m gradually getting to, do not survive more than a year and are adults only a very short amount of this time). Adults then move upstream into smaller streams and reproduce. Reproduction occurs by spawning (egg and sperm release) into shallow, excavated depressions in gravel beds, and the hatched offspring move downstream and spend much of their lifespan in the benthos.
Lampreys are typically thought of as blood-suckers. Indeed, many of the most well-known members of this are fish parasites that kill their host and cause untold economic damage. The introduction of sea lampreys into the
With all that context, why is there a lamprey species listed as a Threatened species in
Hall and Moore (1954) also described the Chestnut Lamprey’s ecology and habits in
These days, the species if found in
G.E. Hall and G.A. Moore. 1954.