Lamprey |
Sea lamprey from Sweden
|
Scientific classification |
Kingdom: |
Animalia
|
Phylum: |
Chordata
|
Class: |
Cephalaspidomorphi
|
(unranked) |
Hyperoartia
|
Order: |
Petromyzontiformes
|
Family: |
Petromyzontidae
|
|
Subfamilies |
Geotriinae
Mordaciinae
Petromyzontinae |
A lamprey (sometimes also called lamprey eel)
is a
jawless fish with a toothed, funnel-like sucking mouth, with
which most species bore into the flesh of other fish to suck
their blood. In zoology, lampreys are often not considered to be true
fish because of their vastly different morphology and
physiology.
Physical description
Lampreys live mostly in coastal and fresh waters,
although at least one species, Geotria australis,
probably travels significant distances in the open ocean, as
is evidenced by the lack of reproductive isolation between
Australian and New Zealand populations, and the capture of a
specimen in the Southern Ocean between Australia and
Antarctica. They are found in most temperate regions except
Africa. Their larvae have a low tolerance for high water
temperatures, which is probably the reason that they are not
found in the tropics. Outwardly resembling eels in that they
have no scales, an adult lamprey can range anywhere from 13
to 100 centimetres (5 to 40 inches) long. Lampreys have one
or two dorsal fins, large eyes, one nostril on the top of
their head, and seven gills on each side. The unique
morphological characteristics of lampreys, such as their
cartilaginous skeleton, means that they are the sister taxon
(see cladistics) of all living jawed vertebrates (gnathostomes)
and are not classified within the Vertebrata itself. The
hagfish, which superficially resembles the lamprey, is
the sister taxon of the lampreys and gnathostomes (a clade
termed the
Craniata).
Basic external anatomy of the lamprey
Mouth of a
sea lamprey
Lampreys begin life as burrowing freshwater
larvae (ammocoetes). At this stage, they are toothless, have
rudimentary eyes, and feed on microorganisms. This larval
stage can last five to seven years and hence was originally
thought to be an independent organism. After these five to
seven years, they transform into adults in a metamorphosis
which is at least as radical as that seen in amphibians, and
which involves a radical rearrangement of internal organs,
development of eyes and transformation from a mud-dwelling
filter feeder into an efficient swimming predator, which
typically moves into the sea to begin a predatory/parasitic
life, attaching to a fish by their mouths, secreting an
anticoagulant to the host, and feeding on the blood and
tissues of the host. In most species this phase lasts about
18 months. Whether lampreys are predators or parasites is a
blurred question.
Not all lampreys can be found in the sea. Some lampreys
are landlocked and remain in fresh water, and some of these
stop feeding altogether as soon as they have left the larval
stage. The landlocked species are usually rather small.
To reproduce, lampreys return to fresh water (if they
left it), build a nest, then spawn, that is, lay their eggs
or excrete their semen, and then invariably die. In
Geotria australis, the time between ceasing to feed at
sea and spawning can be up to 18 months long.
Recent studies reported in Nature suggest that lampreys
have evolved a unique type of immune system with parts that
are unrelated to the antibodies found in mammals. They also have a very high tolerance to iron
overload, and have evolved biochemical defenses to detoxify
this metal.
Fossil lampreys
Lamprey fossils are exceedingly rare; cartilage does not
fossilize as readily as bone. Until 2006, the oldest known
fossil lampreys were from Early
Carboniferous limestones[1], 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 ("Middle 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, as well as about 80 myomeres of its musculature.
A few months later, in the 27 October issue of Nature,
an even older fossil lamprey, dated 360 Mya, 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
The taxonomy presented here is that given by Fisher,
1994. This work classifies lampreys as the sole living
members of the class
Cephalaspidomorphi.[2]
The lampreys entail the single order Petromyzontiformes
and family Petromyzontidae.[3]
Within this family, there are 40 recorded species in nine
genera and three subfamilies:
- Subfamily
Geotriinae
- Genus
Geotria
-
Geotria australis (Gray,1851)
- Subfamily
Mordaciinae
- Genus
Mordacia
- Mordacia lapicida (Gray, 1851)
Mordacia mordax (Richardson, 1846)
Mordacia praecox (Potter, 1968)
- Subfamily
Petromyzontinae
- Genus
Caspiomyzon
-
Caspiomyzon wagneri (Kessler, 1870)
- Genus
Eudontomyzon
- Eudontomyzon danfordi (Regan, 1911)
Eudontomyzon hellenicus (Vladykov, Renaud, Kott
and Economidis, 1982)
Eudontomyzon mariae (Berg, 1931)
Eudontomyzon morii (Berg, 1931)
Eudontomyzon stankokaramani (Karaman, 1974)
Eudontomyzon vladykovi (Oliva and Zanandrea,
1959)
- Genus
Ichthyomyzon
- Ichthyomyzon bdellium (Jordan, 1885) - Ohio
lamprey
Ichthyomyzon castaneus Girard, 1858 - chestnut
lamprey
Ichthyomyzon fossor (Reighard and Cummins, 1916)
- northern brook lamprey
Ichthyomyzon gagei (Hubbs and Trautman, 1937) -
southern brook lamprey
Ichthyomyzon greeleyi (Hubbs and Trautman, 1937)
- mountain brook lamprey
Ichthyomyzon unicuspis (Hubbs and Trautman,
1937) - silver lamprey
- Genus
Lampetra
- Lampetra aepyptera (Abbott, 1860) - least
brook lamprey
Lampetra alaskensis (Vladykov and Kott, 1978)
Lampetra appendix (DeKay, 1842) - American brook
lamprey
Lampetra ayresii (Günther, 1870)
Lampetra fluviatilis (Linnaeus, 1758)
Lampetra hubbsi (Vladykov and Kott, 1976) - Kern
brook lamprey
Lampetra lamottei (Lesueur, 1827)
Lampetra lanceolata (Kux and Steiner, 1972)
Lampetra lethophaga (Hubbs, 1971) - Pit-Klamath
brook lamprey
Lampetra macrostoma (Beamish, 1982) - Vancouver
lamprey
Lampetra minima (Bond and Kan, 1973) - Miller
Lake lamprey
Lampetra planeri (Bloch, 1784)
Lampetra richardsoni (Vladykov and Follett,
1965) - western brook lamprey
Lampetra similis (Vladykov and Kott, 1979) -
Klamath lamprey
Lampetra tridentata (Richardson, 1836) - Pacific
lamprey
- Genus
Lethenteron
- Lethenteron camtschaticum (Tilesius, 1811)
Lethenteron japonicum (Martens, 1868)
Lethenteron kessleri (Anikin, 1905)
Lethenteron matsubarai (Vladykov and Kott, 1978)
Lethenteron reissneri (Dybowski, 1869)
Lethenteron zanandreai (Vladykov, 1955)
- Genus
Petromyzon
-
Petromyzon marinus (Linnaeus, 1758) -
sea lamprey
- Genus
Tetrapleurodon
- Tetrapleurodon geminis (Alvarez, 1964)
Tetrapleurodon spadiceus (Bean, 1887)
Relation to humans
Lampreys have long been used as food for humans. 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"
[1].
Especially in Southwestern Europe (Portugal, Spain,
France) they are still a highly prized delicacy. Overfishing has reduced their number in those parts.
Lampreys are also consumed in South Korea.
Lampreys attached to a
lake trout
On the other hand, 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. Since the majority of North American
consumers, unlike Europeans, refuse to accept lampreys as
food fish, the Great Lakes fishery has been very adversely
affected by their invasion. They are now fought mostly in
the streams that feed the lakes, with special barriers and
poisons called lampricides, which are harmless to most other
aquatic species. However those programs are complicated and
expensive, and they do not eradicate the lampreys from the
lakes but merely keep them in check. New programs are being
developed including the use of sterilization of male lamprey
by trapping of prespawn adults. Research is currently under
way on the use of pheromones and how they may be used to
disrupt the life cycle (Sorensen, et al., 2005). 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.
Trivia
Vedius Pollio
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 to be put to death
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
[2]
Philip Larkin
Christopher Warner, a character in Philip Larkin's early
novel Jill is said to have attended a fictional minor
public school called Lamprey College.
King Henry I
Henry I of England was said to have died from eating too
many lampreys, of which he was fond of eating
[3].
Notes
- ^
From the
Mississippian Mazon Creek lagerstätte and the Bear Gulch
Limestone sequence.
- ^
Cephalaspidomorpha is sometimes given as a subclass
of the Cephalaspidomorphi.
- ^
Petromyzoniformes and Petromyzonidae are
sometimes used as alternative spellings for
Petromyzontiformes and Petromyzontidae respectively.
References
- Mee-mann Chang et
al. (2006). "A
lamprey from the Cretaceous Jehol biota of China".
Nature 441: 972-974 (22 June 2006).
- 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.
- 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: 981-984.
External links