Cross reference: Agnatha    Lamprey Receptors  
Lamprey Fast-Slow Twitch    Lamprey Locomotion     
Lamprey Feeding & Respiration   

Lamprey - Wikipedia  
Lampreys (sometimes also called, inaccurately, lamprey eels) are any jawless fish of the order Petromyzontiformes, placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like sucking mouth. The common name "lamprey" is probably derived from Latin lampetra, which may mean "stone licker" (lambere "to lick" + petra "stone"), though the etymology is uncertain.[3]

Currently there are about 38 known extant species of lampreys.[4] Although they are well known for boring into the flesh of other fish to suck their blood, in fact only a minority do so;[5] only 18 species of lampreys are actually parasitic.[6] The lampreys are a very ancient lineage of vertebrates, though their exact relationship to hagfishes and jawed vertebrates is still a matter of dispute.


mbbiology - Lamprey   
A well written, non-technical article with good diagrams available online for free. 


Life ProcessLifeCycle.jpg

Sea lamprey #1  (Goog)   
Full length article available online for free. 
Working in pairs, sometimes with a second female assisting, they make depressions 2 to 3 feet in diameter and about 6 inches deep in the stream bed in stretches where the bottom is stony or pebbly, dragging the stones downstream in a pile with their suckerlike mouths. And they are able to move stones as large as one's fist. It is in these depressions that the eggs are deposited, not among the piles of discarded stones that have often been described as "nests." It seems that they all die after spawning; not only have they often been found dead, but their intestines atrophy, they are attacked by fungus, and they become so debilitated that recovery seems out of the question.

    The larvae are different in appearance from the adults: blind, toothless, with mouths and fins of different shape. They continue in this state for a period estimated as 3 to 4 years, during most of which time they live in burrows in the mud or sand, or hide under stones. They are abundant in the mud of flats near the mouths of small tributary streams of river systems such as the Delaware and Susquehanna, where lampreys still breed in large numbers, and they subsist on minute organisms. At the end of this larval period, when they have grown to a length of 4 to 6 inches, they undergo transformation to the adult form and structure, an event occupying about two months, August to September or October. They run down to the sea in November or December, to live and grow there for one or two years, so that large ones, not yet mature, are to be found in salt water all the year round.

sea lamprey #2   
Full length article available online for free. 

Marine Lamprey (Goog)   
Full length article available online for free. 
The sea lamprey, like all agnathans, lacks bony teeth and jaws. Nevertheless it has an impressive oral armament of conical teeth made of keratin, the same structural protein found in human hair and nails. The lamprey even has teeth on its tongue. The oral apparatus of the adult lamprey is a sucking disk lined with whorls of over 100 of these teeth. The adult attaches to a bony fish in the ocean with the oral disk and rasps through the skin with the teeth on its tongue. It feeds on the body fluids and muscle tissue as it gets a free ride around the sea.
Lamprey breed in the Connecticut River's tributaries in late May and early June. Spawning takes place in stretches of streams where the bottom is stony or pebbly. Working in pairs, a male and a female make depressions 2 to 3 feet in diameter and about 6 inches deep in the streambed by dragging away stones by means of their oral discs, leaving the stones in a pile downstream. Stones as large as a baseball may be moved. The female now secures herself by means of her oral disc to some large stone near the upstream end of the nest. Her mate attaches himself in the same way near her and wraps himself partly round her; then both stir up the sand with vigorous movements while eggs and milt are simultaneously deposited. Sand grains stick to the fertilized eggs and the larvae develop in the stream's sediments.
    After spawning the parents die. The larval or ammocoete stage lasts from 3 to 5 years, during which time the larvae live under stones or in the mud and subsist entirely on microscopic organisms filtered from the water. When the larvae reach 4 to 5 inches in length, they undergo transformation to the adult form and migrate downstream to the sea.

Lamprey - The Canadian Encyclopedia   
Brief, well written article available online for free. 
For respiration and feeding, water enters the mouth and is extruded through the gill openings. ... In adults, water for respiration enters and exits only through the gill openings."  
    My comment
This is another reference which seems to accept the idea that respiration is through the gills. 

Sea Lamprey Biology - NYS Dept. of Environmental Conservation  
    Well written, non-technical article available online for free. 

Mating Pheromone Reception and Induced Behavior in Ovulating Female Sea Lampreys (Goog) 
Only abstract available online. 
We conclude ... that olfaction is the only means for ovulating females to detect a pheromone that is released by spermiating males.

23.  Hardisty MW.  (1979).  Biology of the Cyclostomes.  Chapman and Hall.  London.     

181119 - 1037