BIO 203


     Silver lamprey undergo three stages during their lifespans.  The first is simply the time period where the individual is an egg. The second stage is known as the ammocoete or larval stage.  The final stage is the adult stage, which is the form people most commonly think of when they hear the term lamprey (Minnesota DNR 2008).
    Lamprey spawn sometime between April and June depending on the location they are found.  Ideally Silver Lamprey spawn when water temperatures reach anywhere from 13 to 18 degrees Celsius or about fifty degrees Fahrenheit (Minnesota DNR 2008; Ohio DNR 2012).  Silver Lamprey spawn in small rivers and streams with rocky or gravel like stream and river beds.  Silver Lampreys prefer to spawn near rifles in the stream or places where the water is somewhat shallow and fast moving (Ohio DNR 2012; Ontario Fisheries).  Male Silver lamprey are responsible for constructing the nests (NY Falls 2013).  They do so by using their sucker-like mouths to pick up rocks and other debris to form a nest or shallow bowl-shaped hole in the streambed (Georgia Bay Biosphere Reserve).  Multiple males often work together to create a pit, and this nest if then often used by multiple mating pairs (Ohio DNR 2012). Silver Lamprey have actually been known to share and occupy the same nest as Sea Lamprey, who are an invasive species that occupy many of the same spawning grounds (NY Falls 2013; Georgia Bay Biosphere Reserve).  Sea Lamprey, Petromyzon marinus, are an invasive species of lamprey that often will share spawning sites and nest with Silver lamprey.  Courtesy Wiki Commons.
    For Silver Lamprey and many of their relatives mating is a fairly simple process.  The female uses her sucker-like mouth to hold on to a rock, then the male attaches himself to the female’s head.  The pair then intertwine and vibrate vigorously while eggs and sperm are released simultaneously and combine to form zygotes.  Females release an estimated 10,000 eggs, with each egg being about one millimeter in diameter ( 1999).  After the male and female spawn, their life cycles are complete and they soon after die (Ohio DNR 2012; Minnesota DNR 2008).  

     The fertilized eggs hatch in approximately ten to twelve days after fertilization.  The newly hatched lamprey are in a laval state and called ammocetes.  Interestingly in the ammocete stage Silver Lamprey are actually filter feeders who live solely on organic material and small organisms (Minnesota DNR 2008). They live in the mud and sand of rivers and streams for anywhere from three to seven years (Minnesota DNR 2008; 1999).  When ammocetes reach about three inches long they metamorphosize into adult lamprey. Upon becoming adults, Silver Lamprey grow become to become parasites, and then move to larger bodies of water like lakes and rivers where they find and attach to a host ( 1999).  Silver Lamprey live their lives for one or two years as parasites until they reach sexual maturity at the age of anywhere from six to eight years of age.  At this point Silver Lamprey return to streams to spawn (EOL; Georgia Bay Biosphere Reserve).

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