Lampreys (Order Petromyzontiformes) are an ancient lineage of fishes. They are the most primitive fishes swimming in the waters of Arkansas and among the most primitive vertebrates in the world.
The complete absence of hinged jaws differentiates lampreys from all other fishes in Arkansas. While they are sometimes mistaken for American Eels (Anguilla rostrata), which are also found in our rivers, the resemblance is entirely superficial. Lampreys can be readily distinguished from eels by their unique mouth structure, complete lack of scales, lack of any paired fins, single nostril on top of the head, entirely cartilaginous skeleton, and the presence of seven prominent round external gill slits.
A lamprey’s most notable feature is its mouth. Instead of having hinged jaws, a lamprey’s mouth consists of a cup-shaped suction disk full of rasping teeth. In parasitic lampreys, the disk and its teeth are used to attach to the side of a fish host, and then the lamprey’s abrasive, file-like tongue is used to pierce the host’s body so that the lamprey can feed on blood and other bodily fluids and tissues. Lampreys may also use their suction abilities to anchor to substrate in swift current or move along a stream bed.
While lampreys are notorious for being parasites on other fish, some species are completely non-parasitic. Of the five species that occur in Arkansas, two are parasitic and three are non-parasitic. All lampreys begin life as a filter-feeding larvae known as ammocoetes, which resemble adults in overall body shape, but lack the sucking disk, abrasive teeth, or large eyes of adult lampreys. An ammocoete spends most of its time burrowing into the stream bed in areas with soft sand or silt, using its narrow, hood-like mouth to strain microorganisms and organic material from the water. After a few years, the ammocoete will make a dramatic transformation into an adult lamprey. It will develop large eyes and the large oral sucking disk, as well as other major changes to its internal organs and systems.
-in-situ-for-email.jpg?sfvrsn=218db0a3_0&MaxWidth=340&MaxHeight=400&ScaleUp=false&Quality=High&Method=ResizeFitToAreaArguments&Signature=97CEE64CC1F4BF73B68730E34CAABA224979F9F7 "01 Chesnut Lamprey (Ichthyomyzon castaneus) in situ for email")
In parasitic species, such as the Chestnut Lamprey (Ichthyomyzon cataneus), the oral disk is wider than the head and full of well-developed teeth; it is used to attach to the side of a fish host so that the lamprey can feed. A parasitic lamprey may spend several days feeding before dropping off. The fish host typically doesn’t die as a direct result of an attack from this species, although it may die due to infection of a wound caused by the attack.
-blog.jpg?sfvrsn=5361cebe_0&MaxWidth=340&MaxHeight=400&ScaleUp=false&Quality=High&Method=ResizeFitToAreaArguments&Signature=F614BB3A1B978A5BF4665BCFF530B4CE42416EF7 "02-Southern-Brook-Lamprey-(Ichthyomyzon-gagei)-blog")
In non-parasitic species, such as the Southern Brook Lamprey (Ichthyomyzon gagei), the oral disk is not wider than the head and the rasping teeth are present but less well developed, particularly in the more posterior portion of the disk. Adult non-parasitic lampreys do not eat, as they have greatly reduced, non-functioning digestive tracts. Instead, they live off fat reserves, accumulated during the larval stage for energy and nutrients, only long enough to spawn once before dying. Both parasitic and non-parasitic lampreys exhibit a reproductive strategy known as semelparity in which a species has only one reproductive episode before death.
In other parts of the U.S., such as the Great Lakes region, predation by the invasive Sea Lamprey (Petromyzon marinus) has become a major ecological and economic issue, devastating populations of native fish species. It is important to note that this species does not occur in Arkansas. In areas where they are not invasive, parasitic lampreys have co-evolved with their fish hosts, and typically do not have a major impact on host populations. They are a fascinating part of our aquatic ecosystems.
On a recent joint survey by the Arkansas Natural Heritage Commission (ANHC) and Arkansas Game and Fish Commission (AGFC) in an Izard County stream, Jeff Quinn (AGFC stream biologist) and I collected one of the rarer lamprey species in the state, the non-parasitic Least Brook Lamprey (Lampetra aepyptera). Only around 40 individuals of this diminutive species have been collected in Arkansas, and until now, the species had never been documented in this creek. Documenting previously unknown populations of rare species and tracking all known populations of these species are a vital role of the ANHC.
Photos:
Photo 1: Comparison of a Chestnut Lamprey (Ichtyomyzon castaneus), above, and an American Eel (Anguilla rostrata), below. Photos by Dustin Lynch.
Photo 2: The oral disks of a non-parasitic species, the Southern Brook Lamprey (Ichthyomyzon gagei) at left, and a parasitic species, the Chestnut Lamprey (Ichtyomyzon castaneus), at right. The Southern Brook Lamprey's oral disk is not wider than the head and the rasping teeth are present but less well developed, particularly in the more posterior portion of the disk. The Chestnut Lamprey's oral disk is wider than the head and full of well-developed teeth; it is used to attach to the side of a fish host so that the lamprey can feed. Photos by Dustin Lynch.
Photo 3: Ammocoete, the filter-feeding larva of a lamprey, overhead view (top) and lateral view (bottom). Photos by Dustin Lynch.
Photo 4: Chestnut Lamprey (Ichthyomyzon castaneus), a common parasitic lamprey species in Arkansas, from the Ouachita River. Photo by Dustin Lynch.
Photo 5: Southern Brook Lamprey (Ichthyomyzon gagei), a common non-parasitic lamprey species in Arkansas, from the Maumelle River. Photo by Dustin Lynch.
Photo 6: Least Brook Lamprey (Lampetra aepypytra), a non-parasitic lamprey that is rare in Arkansas. Recently found on a survey in Izard County. Photo by Dustin Lynch.
Photo 7: A Chestnut Lamprey (Ichthyomyzon castaneus) uses its oral disk to latch onto ANHC Aquatic Ecologist Dustin Lynch's hand. Photo by Dustin Lynch.
The complete absence of hinged jaws differentiates lampreys from all other fishes in Arkansas. While they are sometimes mistaken for American Eels (Anguilla rostrata), which are also found in our rivers, the resemblance is entirely superficial. Lampreys can be readily distinguished from eels by their unique mouth structure, complete lack of scales, lack of any paired fins, single nostril on top of the head, entirely cartilaginous skeleton, and the presence of seven prominent round external gill slits. 
A lamprey’s most notable feature is its mouth. Instead of having hinged jaws, a lamprey’s mouth consists of a cup-shaped suction disk full of rasping teeth. In parasitic lampreys, the disk and its teeth are used to attach to the side of a fish host, and then the lamprey’s abrasive, file-like tongue is used to pierce the host’s body so that the lamprey can feed on blood and other bodily fluids and tissues. Lampreys may also use their suction abilities to anchor to substrate in swift current or move along a stream bed.
While lampreys are notorious for being parasites on other fish, some species are completely non-parasitic. Of the five species that occur in Arkansas, two are parasitic and three are non-parasitic. All lampreys begin life as a filter-feeding larvae known as ammocoetes, which resemble adults in overall body shape, but lack the sucking disk, abrasive teeth, or large eyes of adult lampreys. An ammocoete spends most of its time burrowing into the stream bed in areas with soft sand or silt, using its narrow, hood-like mouth to strain microorganisms and organic material from the water. After a few years, the ammocoete will make a dramatic transformation into an adult lamprey. It will develop large eyes and the large oral sucking disk, as well as other major changes to its internal organs and systems. -in-situ-for-email.jpg?sfvrsn=218db0a3_0 "01 Chesnut Lamprey (Ichthyomyzon castaneus) in situ for email")
In parasitic species, such as the Chestnut Lamprey (Ichthyomyzon cataneus), the oral disk is wider than the head and full of well-developed teeth; it is used to attach to the side of a fish host so that the lamprey can feed. A parasitic lamprey may spend several days feeding before dropping off. The fish host typically doesn’t die as a direct result of an attack from this species, although it may die due to infection of a wound caused by the attack. -blog.jpg?sfvrsn=5361cebe_0 "02-Southern-Brook-Lamprey-(Ichthyomyzon-gagei)-blog")
In non-parasitic species, such as the Southern Brook Lamprey (Ichthyomyzon gagei), the oral disk is not wider than the head and the rasping teeth are present but less well developed, particularly in the more posterior portion of the disk. Adult non-parasitic lampreys do not eat, as they have greatly reduced, non-functioning digestive tracts. Instead, they live off fat reserves, accumulated during the larval stage for energy and nutrients, only long enough to spawn once before dying. Both parasitic and non-parasitic lampreys exhibit a reproductive strategy known as semelparity in which a species has only one reproductive episode before death.In other parts of the U.S., such as the Great Lakes region, predation by the invasive Sea Lamprey (Petromyzon marinus) has become a major ecological and economic issue, devastating populations of native fish species. It is important to note that this species does not occur in Arkansas. In areas where they are not invasive, parasitic lampreys have co-evolved with their fish hosts, and typically do not have a major impact on host populations. They are a fascinating part of our aquatic ecosystems.
On a recent joint survey by the Arkansas Natural Heritage Commission (ANHC) and Arkansas Game and Fish Commission (AGFC) in an Izard County stream, Jeff Quinn (AGFC stream biologist) and I collected one of the rarer lamprey species in the state, the non-parasitic Least Brook Lamprey (Lampetra aepyptera). Only around 40 individuals of this diminutive species have been collected in Arkansas, and until now, the species had never been documented in this creek. Documenting previously unknown populations of rare species and tracking all known populations of these species are a vital role of the ANHC.
Photos:
Photo 1: Comparison of a Chestnut Lamprey (Ichtyomyzon castaneus), above, and an American Eel (Anguilla rostrata), below. Photos by Dustin Lynch.
Photo 2: The oral disks of a non-parasitic species, the Southern Brook Lamprey (Ichthyomyzon gagei) at left, and a parasitic species, the Chestnut Lamprey (Ichtyomyzon castaneus), at right. The Southern Brook Lamprey's oral disk is not wider than the head and the rasping teeth are present but less well developed, particularly in the more posterior portion of the disk. The Chestnut Lamprey's oral disk is wider than the head and full of well-developed teeth; it is used to attach to the side of a fish host so that the lamprey can feed. Photos by Dustin Lynch.
Photo 3: Ammocoete, the filter-feeding larva of a lamprey, overhead view (top) and lateral view (bottom). Photos by Dustin Lynch.
Photo 4: Chestnut Lamprey (Ichthyomyzon castaneus), a common parasitic lamprey species in Arkansas, from the Ouachita River. Photo by Dustin Lynch.
Photo 5: Southern Brook Lamprey (Ichthyomyzon gagei), a common non-parasitic lamprey species in Arkansas, from the Maumelle River. Photo by Dustin Lynch.
Photo 6: Least Brook Lamprey (Lampetra aepypytra), a non-parasitic lamprey that is rare in Arkansas. Recently found on a survey in Izard County. Photo by Dustin Lynch.
Photo 7: A Chestnut Lamprey (Ichthyomyzon castaneus) uses its oral disk to latch onto ANHC Aquatic Ecologist Dustin Lynch's hand. Photo by Dustin Lynch.