Class: Petromyzonti (Lampreys)
"Some species live in fresh water for their entire lives. Others, like the sea lamprey (Petromyzon marinus) ... are anadromous. That is, they are hatched and grow in fresh water, migrate to the ocean to mature, and then return to fresh water to spawn. Lamprey eggs hatch into small larvae, known as ammocoetes, which are not predators at all; they lack the sucker mouths of the adults, and feed by producing strands of mucus and trapping food particles. The ammocoetes stage may last up to seven years before its metamorphosis into an adult. Adult lampreys live for a year or two before spawning, and then die soon afterwards. The adults bear seven separate gill openings and have an internal skeleton of cartilage. Unlike hagfishes, with which they were once classified, lampreys have a complete braincase and rudimentary true vertebrae. Uniquely among living vertebrates, lampreys also have a single "nostril" on the dorsal side of the head -- a feature they share with various fossil jawless fish, which had a similar opening.
Lampreys have a round, suckerlike jawless mouth filled with rows of horny teeth, and a rasplike "tongue". An internal ring of cartilage supports the rim of the mouth. Although lampreys sometimes prey on small invertebrates, they are better known as predators on fish. Fastening on to living fish, lampreys rasp into the flesh and feed on the body fluids. A fish attacked by lampreys may be severely weakened or even killed. Because they lack mineralized tissues such as bone, lampreys are rare as fossils, and their early evolutionary history is still poorly known."
Source: https://ucmp.berkeley.edu/vertebrates/basalfish/petro.html
Order: Petromyzontiformes
Family: Geotriidae (Pouched and Argentinian lampreys) [1 genus (Geotria); 2 species]
—No subordinate taxa
Family: Mordaciidae (Southern Topeyed lampreys) [1 genus (Mordacia); 3 species]
—No subordinate taxa
Family: Petromyzontidae (Northern lampreys) [2 subfamilies (9 genera)1; 45+ species]
| Scientific Name & Authority | Common Name/s | Distribution (Habitat) | Status (Last Record) | Taxon Profile |
| Entosphenus minimus (Bond & Kan, 1973) | Miller Lake lamprey | Oregon, USA (freshwater [potamodromous]) | Rediscovered | Access |
| Lampetra sp. nov. 'Migratory' | Ukranian migratory lamprey | Ukraine (freshwater, marine [anadromous]) | Rediscovered | Access |
| Tetrapleurodon spadiceus (Bean, 1887) | Chapala lamprey, Mexican lamprey | Mexico (freshwater [potamodromous]) | Missing (1987) | Access |
1 Lampetrinae (Caspiomyzon, Entosphenus, Eudontomyzon, Lampetra, Lethenteron, Occidentis, Tetrapleurodon); Petromyzontinae (Ichthyomyzon, Petromyzon)
Statistics
| Conservation status | Number of taxa (in percentage) |
| Extinct | 0 |
| Missing | 1 (33.34%) |
| Extinct in the Wild | 0 |
| Possibly Extinct in the Wild | 0 |
| Globally Rediscovered | 2 (66.66%) |
| Rediscovered in the Wild | 0 |
| Reintroduced | 0 |
| Hypothetical | 0 |
| Invalid | 0 |
| Erroneously listed | 0 |
| Uncertain status | 0 |
| Total | 3 |