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Silver lamprey

Ichthyomyzon unicuspis

What do they look like?

Silver lampreys have a single, continuous dorsal fin, which is connected to a short, round caudal fin. They do not have jaws and instead have an oral disc with sharp teeth. Likewise, their skeletons are made of cartilage. The larvae of silver lampreys look very similar to the larvae of northern brook lampreys. The larvae are brown to gray-brown on their back and sides. They also have a pale median line along their backs. Most young adults have a tan coloration and are lighter on their stomachs than on their backs, although some have a slate coloration at this stage. Mature adults range from blue to blue-gray on their sides and back, and black, grey, or blue on their bellies. Individuals that reach over 150 mm in length become slightly darker, but even when this happens, they are still lighter than chestnut lampreys. (Becker, 1983; Werner, 2004)

  • Range mass
    1.6 to 104.1 g
    0.06 to 3.67 oz
  • Average mass
    28.4 g
    1.00 oz
  • Range length
    103 to 326 mm
    4.06 to 12.83 in
  • Average length
    211 mm
    8.31 in

Where do they live?

Silver lampreys are found in southern Canada and the northern United States. In Canada, they are found in rivers and lakes of Ontario and Quebec. In the United States, they can be found from Minnesota to Vermont, and as far south as Kentucky. Their range is centered in the Great Lakes and any tributaries or outflows, as well as the Ohio, Mississippi, St. Lawrence, and Hudson Rivers. (Renaud, et al., 2009; Werner, 2004)

What kind of habitat do they need?

Silver lampreys are found in large, clear rivers and lakes. They usually live in areas where they can get to their large host fishes such as flathead catfish, northern pike, paddlefish, and lake sturgeon. During spawning in the spring, silver lampreys are found in clear, medium to large-sized rivers with gravel and sandy bottoms. They can be found at many different water depths. During their parasitic adult stage, silver lampreys live in lakes, however, as larvae they live in rivers and streams. (Becker, 1983; Manion and Hanson, 1980)

  • Aquatic Biomes
  • pelagic
  • lakes and ponds
  • rivers and streams

How do they grow?

Larvae hatch about 5 days after the eggs are deposited into the nest. When the eggs hatch and the larvae leave the nest, they drift downstream and burrow into sand and muck. Once the larvae have burrowed into the substrate, they filter feed from the water, feeding on algae, diatoms, pollen, and protozoa. Silver lampreys stay in the larval life stage for about four to seven years. At the end of this period, lampreys use stored nutrients to transform into adults. (Becker, 1983; Rovainen, 1996)

How do they reproduce?

Parasitic adult lampreys move upstream to spawn. Males begin nest building with the help of females. Nests must be built at depths of 13 to 170 cm, with water temperature ranging from 10 to 26.1°C. Gravel about 3 cm in diameter can be used for nest building. The nests are about 30 cm in diameter and have an inside area of about 11 cm. Nest building usually takes one to three days. Once the nest is complete, the male and female spawn. Sea lampreys build their nests in deeper, swifter moving waters. Because these species will share nests, silver lampreys will nest in deeper than usual waters when such nests are present. Silver lampreys sometimes take part is mass spawning, where multiple individuals and lamprey species spawn in one nest. Sometimes individuals spawn in a nest that has already been constructed, often by sea lampreys, as they tend to build larger nests on average. In Michigan, silver lampreys have been found in nests with sea lampreys and American brook lampreys. In Wisconsin, silver lampreys have only been found with sea lampreys. Male silver lampreys are not as competitive as male sea lampreys, which mostly mate in pairs. (Cochran and Lyons, 2004; Cochran, et al., 2008; Manion and Hanson, 1980; Werner, 2004)

As the water temperature increases during spring, adult silver lampreys move upstream in rivers to spawn. Once the nest is built, the female attaches her oral disc to one of the rocks in the nest and the male follows. The male and female release the eggs and sperm at the same time and the eggs sink to the bottom of the nest. (Manion and Hanson, 1980)

  • How often does reproduction occur?
    Silver lampreys only spawn once and die shortly after.
  • Breeding season
    Silver lampreys spawn from April to July.

Because silver lampreys die shortly after spawning they do not show any parental care. (Manion and Hanson, 1980)

  • Parental Investment
  • no parental involvement

How long do they live?

Silver lampreys can live 5 to 9 years, from larvae to their adult form. They actually spend a majority of their life under ground as larvae before metamorphosis. After metamorphosis, silver lampreys live about 1 to 2 years before spawning and dying. (Werner, 2004)

  • Typical lifespan
    Status: wild
    5 to 9 years

How do they behave?

Silver lampreys spend about 75% of their life burrowed in riverbeds as filter feeding larvae. The rest of their life is parasitic, where they swim to a large host fish and attach to their body to feed on their blood and bodily fluids. Because of this, silver lampreys rarely interact with each other except during spawning. Likewise, they mostly interact with other species when they attach to hosts for feeding. Silver lampreys mostly feed at night, possibly to avoid predators. (Cochran, 1986)

Home Range

Silver lampreys do not have a home range. As parasites, these lampreys go wherever their host fish goes. More specifically, they have even been observed attached to lake sturgeon during their migration and spawning season. This can actually help silver lampreys get upstream to their preferred spawning habitat. (Cochran, et al., 2003)

How do they communicate with each other?

Since silver lampreys are mostly solitary and usually only interact with other species while feeding, their senses are developed more for perception than communication. Silver lampreys may be able to use low-frequency electric fields produced by fish to detect prey. Since these fields are weak, a potential host would probably need to be within 10 cm of silver lampreys to be detected. Silver lampreys may also be able to pick up chemical signals. In addition to these senses, silver lampreys have well-developed eyes with an egg-shaped lens. (Bodznick and Preston, 1983; Collin and Fritzsch, 1992; Kawasaki and Rovainen, 1988)

What do they eat?

Silver lampreys eat in different ways in their larval and adult stages. As larvae, silver lampreys filter feed from the bottom of rivers, feeding on algae, pollen, diatoms, and protozoa. In their adult stage, silver lampreys attach themselves with their teeth and oral disc to a large host fish. Their sharp teeth can cut through the flesh of their prey. With their sucker-like mouth, they feed on fish flesh where they attach, but they mainly feed on blood and bodily fluids. Their highest rates of feeding are between June and September. Their host species include lake sturgeon, Atlantic sturgeon, paddlefish, longnose gar, goldfish, common carp, longnose suckers, white suckers, black buffalo, brown bullhead, northern pike, muskellunge, lake whitefish, brook trout, lake trout, white bass, striped bass, rock bass, smallmouth bass, and walleye. (Becker, 1983; Renaud, 2002; Rovainen, 1996)

  • Animal Foods
  • fish
  • blood
  • body fluids

What eats them and how do they avoid being eaten?

Eggs, larvae, and small adult lampreys are preyed upon by many different fish species. In one case, a gull was seen feeding on a silver lamprey on the Fox River in Wisconsin. By feeding mostly at night, silver lampreys may avoid many predators. (Becker, 1983; Cochran and Marks, 1995; Cochran, 1986)

What roles do they have in the ecosystem?

Larval silver lampreys help break down particles by filter feeding on algae, pollen, diatoms, detritus, and protozoa. In their parasitic stage, silver lampreys may help control populations of their host fishes. (Dodds and Whiles, 2010)

Species (or larger taxonomic groups) used as hosts by this species

Do they cause problems?

Lampreys are parasitic on large fish, which are often popular sport and game fish. Even though silver lampreys are parasitic, they do not threaten sport fishing as much as invasive sea lampreys. Silver lampreys are a native species and are found in popular fishing sites. Fishing seems unaffected, even when large numbers of lamprey are present. This suggests that silver lampreys have no negative effects on humans. (Becker, 1983)

How do they interact with us?

Silver lampreys give little economic benefit to humans; however larvae and small adults can be used as bait to catch black bass and catfish. (Becker, 1983)

Are they endangered?

Populations of silver lampreys are stable but may be declining in areas with sea lampreys. Silver lampreys are listed as endangered in Nebraska and South Dakota, and are rare in West Virginia. (Becker, 1983; Renaud, 1997)


Chelsea Blumbergs (author), University of Michigan-Ann Arbor, Jeff Schaeffer (editor), University of Michigan-Ann Arbor, Lauren Sallan (editor), University of Michigan-Ann Arbor, Leila Siciliano Martina (editor), Animal Diversity Web Staff.


Becker, G. 1983. Fishes of Wisconsin. Madison, WI: University of Wisconsin Press.

Bodznick, D., D. Preston. 1983. Physiological characterization of electroreceptors in the lampreys Ichthyomyzon unicuspis and Petromyzon marinus. Journal of Comparative Physiology, 152: 209-217.

Cochran, P. 1986. The daily timing of lamprey attacks. Environmental Biology of Fishes, 16: 325-329.

Cochran, P., D. Bloom, R. Wagner. 2008. Alternative Reproductive Behaviors in Lampreys and their Significance. Journal of Freshwater Ecology, 23: 437-444.

Cochran, P., J. Lyons. 2004. Field and Laboratory Observations on the Ecology and Behavior of the Silver Lamprey (Ichthyomyzon unicuspis) in Wisconsin. Journal of Freshwater Ecology, 19: 245-253.

Cochran, P., J. Lyons, M. Gehl. 2003. Parasitic attachments by overwintering silver lampreys, Ichthyomyzon unicuspis, and chestnut lampreys, Ichthyomyzon castaneus. Environmental Biology of Fishes, 68: 65-71.

Cochran, P., J. Marks. 1995. Biology of the Silver Lamprey, Ichthyomyzon unicuspis, in Green Bay and the Lower Fox River, with a Comparison to the Sea Lamprey, Petromyzon marinus. Copeia, 1995: 409-421.

Collin, S., B. Fritzsch. 1992. Observations on the shape of the lens in the eye of the silver lamprey, Ichthyomyzon unicuspis. Canadian Journal of Zoology, 71: 34-41.

Dodds, W., M. Whiles. 2010. Freshwater Ecology, Second Edition: Concepts and Environmental Application of Limnology. Burlington, MA: Elsevier.

Kawasaki, R., C. Rovainen. 1988. Feeding Behavior by Parasitic Phase Lampreys, Ichthyomyzon unicuspis. Brain Behavior and Evolution, 32: 317-329.

Manion, P., L. Hanson. 1980. Spawning Behavior and Fecundity of Lampreys from the Upper Three Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences, 37: 1635-1640.

Renaud, C. 1997. Conservation status of Northern Hemisphere lampreys (Petromyzontidae). Journal of Applied Ichthyology, 13: 143-148.

Renaud, C. 2002. The Muskellunge, Esox masquinongy, as a host for the Silver Lamprey, Ichthyomyzon unicuspis, in the Ottawa River, Ontario/Quebec. Canadian Field Naturalist, 116: 433-440.

Renaud, C., M. Docker, N. Mandrak. 2009. Taxonomy, Distribution, and Conservation of Lampreys in Canada. American Fisheries Society Symposium, 72: 1-18.

Rovainen, C. 1996. Feeding and Breathing in Lampreys. Brain, Behavior and Evolution, 48: 297-305.

Werner, R. 2004. Freshwater Fishes of the United States: A Field Guide. Syracuse, NY: Syracuse University Press.

University of Michigan Museum of ZoologyNational Science Foundation

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Blumbergs, C. 2014. "Ichthyomyzon unicuspis" (On-line), Animal Diversity Web. Accessed February 27, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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