What is a lamprey? A lamprey is a primitive fish that looks like a worm and dates back to 360 million years ago. There are 38 known species and 7 in Ohio. Three of the species are parasitic and four are non-parasitic. All of them have a non-parasitic juvenile life stage called an ammocete.
Ammocete lamprey found in southeastern Ohio stream.
Image source: Scott Glassmeyer 2016
The lifespan is depending on the species but ranges from 3 to 7 years (Hardisty, 1944). They spend most of their time in the soil as an ammocete feeding on detritus and algae. A study from an Ohio State University master’s student thesis found Sea Lamprey (Petromyzon marinus), as ammocetes, eat more fresh plant an soil organic matter when younger and more algae when older (Evans, 2012).
The eyes of an ammocete are not fully developed because they don’t use their eyes for seeing more than light and dark. They spend the first 3 years in sandy soils usually beneath leaf patches in small rivers and streams.
Head of ammocete lamprey from southeastern Ohio stream.
Image source: Scott Glassmeyer 2016
The dark holes on the side of the “neck” are gill openings where water goes in and out to exchange oxygen across the gills. They do not actively pump water across the gills like most other fish, it simply moves in and out through natural movements.
They metamorphose into adults in the sand and sometimes gravel between July and early winter (Hardisty, 1944). Depending on the species when they metamorphose to adults they transform into parasitic feeding adults and non-parasitic adults (Figure 1).
Figure 1: Life cycles of parasitic and non-parasitic life stages.
Figure source: http://maydenlab.slu.edu/mayden/lamprey/lifehistory.html
Non-parasitic lamprey metamorphose into adults, spawn, and die without feeding. Parasitic lamprey metamorphose into adults, feed on larger fish by latching onto the side and sucking out blood until the victim dies. After feeding and growing, they return to the river, spawn and die. When lamprey are of reproductive age, they spawn in rivers usually at around 10 inches of water right above a riffle in a nest that they dig out. The eggs stay in the substrate for a few weeks and when they hatch, the life cycle repeats itself.
Video Source: Scott Glassmeyer spring 2016
Evans, T. (2012). Assessing Food and Nutritional Resources of Native and Invasive Lamprey Larvae Using Natural Abundance Isotopes. In J. Bauer, M. Daly, & S. Ludsin (Eds.): Presented in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Graduate School of The Ohio State University.
Hardisty, M. W. (1944). The life history and growth of the brook lamprey (Lampetra Planeri). Journal of Animal Ecology, 13, 110-122. doi:10.2307/1444