Lamprey

For other uses, see Lamprey (disambiguation).

Lamprey Temporal range: Late Devonian–Recent PreЄ Є O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Petromyzontida or Hyperoartia
Order:	Petromyzontiformes
Family:	Petromyzontidae
Subfamilies
Geotriinae Mordaciinae Petromyzontinae

Lampreys (sometimes also called lamprey eels) are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers (lambere: to lick, and petra: stone). While lampreys are well-known for those species which bore into the flesh of other fish to suck their blood, most species of lamprey are non-parasitic and never feed on other fish. In zoology, lampreys are sometimes not considered to be true fish because of their distinctive morphology and physiology.

Physical description

Basic external anatomy of the lamprey

Mouth of a Sea lamprey, Petromyzon marinus

Lampreys live mostly in coastal and fresh waters, although some species, (e.g. Geotria australis, Petromyzon marinus, Entosphenus tridentatus) travel significant distances in the open ocean, as evidenced by their lack of reproductive isolation between populations. They are found in most temperate regions except those in Africa. Their larvae (ammocoetes) have a low tolerance for high water temperatures, which may explain why they are not distributed in the tropics.

Adults physically resemble eels, in that they have no scales, and can range anywhere from 13 to 100 centimetres (5 to 40 inches) long. Lacking paired fins, adult lampreys have large eyes, one nostril on the top of the head, and seven gill pores on each side of the head. The unique morphological characteristics of lampreys, such as their cartilaginous skeleton, suggest that they are the sister taxon (see cladistics) of all living jawed vertebrates (gnathostomes), and are usually considered the most basal group of the Vertebrata. They feed on prey as adults by attaching their mouthparts to the target animal's body, then using their teeth to cut through surface tissues until they reach blood and body fluid. They will generally not attack humans unless starved. Hagfish, which superficially resemble lampreys, are the sister taxon of the true vertebrates (lampreys and gnathostomes).

Lampreys provide valuable insight into the evolution of the adaptive immune system, as they possess a convergently evolved adaptive immunity with cells that function like the T cells and B cells seen in higher vertebrates. Lamprey leukocytes express surface variable lymphocyte receptors (VLRs) generated from somatic recombination of leucine-rich repeats gene segments in a recombination activating gene-independent manner.

Geotria australis larvae also have a very high tolerance for free iron in the body, and have well-developed biochemical systems for detoxification of the large quantities of this metal.

Fossils

Lamprey fossils are rare because cartilage does not fossilize as readily as bone. The first fossil lampreys were originally found in Early Carboniferous limestones, laid down in marine sediments in North America: Mayomyzon pieckoensis and Hardistiella montanensis.

In the 22 June 2006 issue of Nature, Mee-mann Chang and colleagues reported on a fossil lamprey from the same Early Cretaceous lagerstätten that have yielded feathered dinosaurs, in the Yixian Formation of Inner Mongolia. The new species, morphologically similar to Carboniferous and modern forms, was given the name Mesomyzon mengae ("Mesozoic lamprey"). The exceedingly well-preserved fossil showed a well-developed sucking oral disk, a relatively long branchial apparatus showing branchial basket, seven gill pouches, gill arches and even the impressions of gill filaments, and about 80 myomeres of its musculature.

Months later, in the 27 October issue of Nature, a fossil lamprey even older than the Mazon Creek genera, dated 360 million years ago, was reported from Witteberg Group rocks near Grahamstown, in the Eastern Cape of South Africa. This species, dubbed Priscomyzon riniensis still strongly resembled modern lampreys despite its Devonian age.

Taxonomy

Some researchers have classified lampreys as the sole surviving representatives of the Linnean class Cephalaspidomorphi. Fossil evidence now suggests that lampreys and cephalaspids acquired their shared characters by convergent evolution. As such, many newer works such as the fourth edition of Fishes of the World classify lampreys in a separate group called Petromyzontida (or Hyperoartia).

The lampreys entail the single order Petromyzontiformes and family Petromyzontidae.

The following taxonomy is based upon the treatment by FishBase as of February 2011. Within this family, there are 43 recorded species in eight genera and three subfamilies:

• Subfamily Geotriinae
  • Genus Geotria
• Subfamily Mordaciinae
  • Genus Mordacia
• Subfamily Petromyzontinae
  • Genus Caspiomyzon
  • Genus Eudontomyzon
  • Genus Ichthyomyzon
  • Genus Lampetra
  • Genus Lethenteron
  • Genus Petromyzon

Taxonomists place lampreys and hagfish in the Subphylum Vertebrata of the phylum Chordata, which also includes the invertebrate subphyla Tunicata (sea-squirts) and the fish-like Cephalochordata (lancelets or `Amphioxus'). Recent molecular and morphological phylogenetic studies place lampreys and hagfish in the super-class Agnatha or Agnathostomata (both meaning without jaws). The other vertebrate super-class is Gnathostomata (jawed mouths) and includes the classes Chondrichthyes (sharks), Osteichthyes (bony fishes), Amphibia, Reptilia, Aves (birds), and Mammalia.

Relation to humans

Uses

Larger lamprey in a restaurant tank about to be cooked and served.

Portuguese Lamprey rice.

Lampreys have long been used as food for humans. They were highly appreciated by ancient Romans. During the Middle Ages, they were widely eaten by the upper classes throughout Europe, especially during fasting periods, since their taste is much meatier than that of most true fish. King Henry I of England is said to have died from eating "a surfeit of lampreys". On March 4th, 1953, Queen Elizabeth's coronation pie was made by the Royal Air Force using lampreys.^{[citation needed]}

Especially in southwestern Europe (Portugal, Spain, and France), larger lampreys are still a highly prized delicacy. Overfishing has reduced their number in those parts. Lampreys are also consumed in Sweden, Finland, Russia, the Baltic countries and South Korea. In Britain, lampreys are commonly used as bait, normally as dead bait. Pike, perch and chub all can be caught on lampreys. Lampreys can be bought frozen from most bait and tackle shops.

Research

The lamprey has been extensively studied because it has a relatively simple brain that is thought in many respects to reflect the brain structure of early vertebrate ancestors. Beginning in the 1970s, Sten Grillner and his colleagues at the Karolinska Institute in Stockholm have used the lamprey as a model system to work out the fundamental principles of motor control in vertebrates, starting in the spinal cord and working upward into the brain. In a series of studies, they found that neural circuits within the spinal cord are capable of generating the rhythmic motor patterns that underlie swimming, that these circuits are controlled by specific locomotor areas in the brainstem and midbrain, and that these areas in turn are controlled by higher brain structures including the basal ganglia and tectum. In a study of the lamprey tectum published in 2007, they found that electrical stimulation could elicit eye movements, lateral bending movements, or swimming activity, and that the type, amplitude, and direction of movement varied as a function of the location within the tectum that was stimulated. These findings were interpreted as consistent with the idea that the tectum generates goal-directed locomotion in the lamprey as it does in other species.

Lampreys are used as a model organism in biomedical research where their large reticulospinal axons are used to investigate synaptic transmission. The axons of lamprey are particularly large and allow for microinjection of substances for experimental manipulation.

As pests

Lampreys attached to a lake trout.

Sea lampreys have become a major plague in the North American Great Lakes after artificial canals allowed their entry during the early 20th century. They are considered an invasive species, have no natural enemies in the lakes and prey on many species of commercial value, such as lake trout. Lampreys are now found mostly in the streams that feed the lakes, with special barriers to prevent the upstream movement of adults, or by the application of toxicants called lampricides, which are harmless to most other aquatic species. However those programs are complicated and expensive, and do not eradicate the lampreys from the lakes but merely keep them in check. New programs are being developed including the use of chemically sterilized male lamprey in a method akin to the sterile insect technique. Research currently under way on the use of pheromones and how they may be used to disrupt the life cycle (Sorensen, et al., 2005) has met with some success. Control of sea lampreys in the Great Lakes is conducted by the U.S. Fish and Wildlife Service and the Canadian Department of Fisheries and Oceans. The work is coordinated by the Great Lakes Fishery Commission.

Lake Champlain, bordered by New York State, Vermont, and Quebec, and New York's Finger Lakes are also home to populations of sea lampreys whose high populations have warranted control. Lake Champlain's lamprey control program is managed by the New York State Department of Environmental Conservation, the Vermont Department of Fish and Wildlife, and the U.S. Fish and Wildlife Service. New York's Finger Lakes sea lamprey control program is managed solely by the New York State Department of Environmental Conservation.

Folklore

Lampreys are called "nine-eyed eels" (i.e., per side) from a counting of their seven external gill slits on a side with one eye and the nostril. A German word for lampreys is `Neunauge(n)' which means `nine-eye(s).

In literature

Illustration from an edition of Tacuinum Sanitatis, 15th century.

Vedius Pollio was punished by Augustus for attempting to feed a clumsy slave to the lampreys in his fishpond.

...one of his slaves had broken a crystal cup. Vedius ordered him to be seized and then put to death, but in an unusual way. He ordered him to be thrown to the huge lampreys which he had in his fish pond. Who would not think he did this for display? Yet it was out of cruelty. The boy slipped from the captor’s hands and fled to Caesar’s feet asking nothing else other than a different way to die — he did not want to be eaten. Caesar was moved by the novelty of the cruelty and ordered him to be released, all the crystal cups to be broken before his eyes, and the fish pond to be filled in... – Seneca, On Anger, III, 40

"Lampreys have been seen before attacking a human in the great lakes. The lamprey let go a few seconds later after realizing its mistake. The man (who chose to be not named) was taken to the hospital with various injuries." – From the Jules Verne's novel Twenty Thousand Leagues Under the Sea.

References

• Mee-mann Chang et al. (2006). "A lamprey from the Cretaceous Jehol biota of China". Nature 441 (7096): 972–974 (22 June 2006). doi:10.1038/nature04730. PMID 16791193. 
• Sorensen, P; Fine, J; Dvornikovs, V; Jeffrey, C; Shao, F; Wang, J; Vrieze, L; Anderson, K; Hoye, T. (2005). "Mixture of new sulfated steroids functions as a migratory pheromone in the sea lamprey". Nature Chemical Biology 1 (November): 324–328. doi:10.1038/nchembio739. PMID 16408070. 
• Fisher (1994). Fishes of the World, Third Edition. John Wiley and Sons. ISBN 0-471-54713-1. 
• Gess, Robert W.; Coates, Michael I.; Rubidge, Bruce S. (2006). "A lamprey from the Devonian period of South Africa". Nature 443 (7114): 981–984. doi:10.1038/nature05150. PMID 17066033. 
• Froese, Rainer, and Daniel Pauly, eds. (2011). "Petromyzontidae" in FishBase. February 2011 version.

External links

• ITIS report on the lampreys, itis.usda.gov
• "Lamprey conservation", cfb.ie
• A Tree of Life diagram showing the relation of Lampreys to other organisms, tellapallet.com
• Lamprey skeletons, scienceblogs.com
• "Scientists from South Africa discover world's oldest fish fossil", News report on 27 October 2006 Nature article, Pravda. (English)
• Alok Jha, Perfect lampreys show little change in 125 m years The Guardian (22 June 2006), guardian.co.uk
• Scientists find lamprey a 'living fossil', uchospitals.edu