Parasitic Lampreys

The Sea Lamprey (Petromyzon marinus) belongs to the order Petromyzontiformes which consists of 40 known extant species of Lamprey; 18 are known to be parasitic. These primitive fish have an antitropical distribution in both fresh and salt water as the young, known as ammocoete, have low thermal tolerance and is non-viable to reproduce in such an area that cannot support offspring. As the name suggests the Sea lamprey spends its adult life occupying coastal waters and oceans. Certain species are known to travel extensive distances for breeding purposes up into freshwater billabongs and periodically land locked habitats providing evidence for isolation by distance and physical barrier (Renaud, C.B 2011).

Figure 1. The Sea Lamprey (Petromyzon marinus). Photographer: Breck P, Kent

The lampreys are notorious for their hematophagus feeding (blood sucking) ability which is only facilitated in post metamorphosed individuals or the adult stage. Sea lampreys have a 3 staged life cycle compromised of the larval, metamorphosis and parasitic stage of which their morphology and physiology undergo drastic changes to cope with the transition from fresh to salt water and their new feeding habits. The lamprey depend on the parasitic relationships with their host as they require blood. They adhere and bore a hole in the flesh using their specialised circular mouth filled with reversed keratinised teeth. Anticoagulants in saliva prevent the host’s blood from clotting and they can maintain a constant supply of food. They poses annular cartilage as opposed to a jaw bone that supports the supraoral and inraoral laminae. This allows the free movement and adaptation to different adhesion surfaces for the lamprey to anchor. The shading of teeth in terms of colour provides an estimate to the age; typically, darkened relates to older teeth. In relation to the age of the teeth is estimated that in a 2 year period the lamprey will replace its teeth in the vicinity of 30 times; they have a hollow core allowing stacked tooth structure as a fast method of teeth renewal (Seagle, H.H. et al, 1982: Beamish, F.W.H. et al 1975)

These vampire like blood sucking creatures rely on a variety of marine hosts in order to survive. Lampreys feeding behaviour has evolved over millions of years and proven the test of time and have also become one of the largest parasitic feeders in the marine ecosystem.

Video with thanks to NatGeo Wild. https://www.youtube.com/watch?v=AzZao6SVMyc

References:

Beamish, F.W.H. & Potter, I.C. 1975. The biology of the anadromous Sea Lamprey (Petromyzon marinus) in New Brunswick. J. Zool., 177: 57–72.

Renaud, C.B. 2011 Lampreys of the world. An annotated and illustrated catalogue of lamprey species known to date. FAO Species Catalogue for Fishery Purposes. No. 5. Rome, FAO. 109 pp.

Seagle, H.H., Jr. & Nagel, J.W. 1982. Life cycle and fecundity of the American Brook Lamprey, Lampetra appendix, in Tennessee. Copeia, 1982(2): 362–366.

Figure 1. Breck P, Kent (n.d). The Sea Lamprey (Petromyzon marinus). Retrieved from http://www.arkive.org/sea-lamprey/petromyzon-marinus/ on 20/04/2015