Lamprey Facts

Lamprey Facts

1. Lampreys developed from jawless fishes that swam through prehistoric waters five hundred million years ago.

2. The jawless fish then died in what later became a coal mine, south of what later was Chicago.

3. Lampreys are similar in general size and shape to hagfishes, but are more closely related to gnathostomes than are hagfishes.

4. Lampreys possess vertebral structures called arcualia, tiny cartilaginous skeletal elements that are homologous with the neural arches of vertebrates.

5. Unlike hagfishes, lampreys possess large well developed eyes and have two semicircular canals.

6. They also are not isosmotic.  Instead well-developed kidneys and chloride cells in the gills regulate the concentration of body fluids and allow lampreys to live in a wide range of salinities.

7. The lamprey’s mouth is located at the base of the oral hood (a fleshy suction cup lined with teeth).

8. The oral hood allows the lamprey to latch on tight to its prey and once attached the lamprey is very hard to dislodge.

9. Lampreys occur in both marine and fresh waters and about half of all species are ectoparasites of fish (the others are non-feeding as adults and live only a few months).Lampreys spawn in streams and the larvae (ammocoetes) live and grow as filter feeders in the stream for 3-7 years before maturing into an adult.  Feeding adults live a year or so before spawning and dying.

10. Parasitic lampreys have a sucker-like mouth with which they attach to fish and rasp away at them with their keratinized teeth.

11. The lamprey produces an anticoagulant as it feeds to maintain blood flow.  When it is full the lamprey detaches, but the open wound on the fish may kill it.  At best the wound is unsightly and largely destroys the fish’s commercial value.

12. Because attached lampreys cannot have a through-flow of water they have to ventilate their gills in a tidal fashion. Water is drawn in and pumped out of the gill slits, which is not very efficient, but is a necessary compromise.

13. Landlocked sea lampreys made their way into the Great Lakes around 1918 and caused the complete collapse of the lake trout fishery by the 1950’s.

14. Lamprey numbers fell as their prey base collapsed and control efforts were introduced.  Trout numbers have since recovered somewhat, but wounding rates are still high.

15. As is the case elsewhere there has been a campaign to control lamprey numbers primarily by using lampricides in steams. Controls do reduce lamprey wounding rates and after control rates have fallen from 60-70 wounds per 100 fish examined to as low as 30 wounds/fish.

16. The origin of jaws was a hugely significant event in the evolution of the vertebrates and the success of the Gnathostomes [the jawed vertebrates, “jaw mouth”] is obvious.  The first jawed vertebrates were the placoderms heavily armored fish which arose in the early Devonian (about 400mya).

17. They also possessed paired pelvic and pectoral fins that gave them much better control while swimming.

18. Vertebrate jaws are made of cartilage derived from the neural crest, the same material as the gill arches (which support the gills).

19. Jaws appear to have arisen by modification of the first cartilaginous gill arches, which aid in gill support and ventilation.

20. Large parasitic species (up to 3’), can kill up to 40 lbs. of prey in lifetime.