Pouch Lamprey, Geotria australis Gray 1851

Other Names: Narrow-mouthed Lamprey, Piharau, Pouched Lamprey, Velasia, Wide-mouthed Lamprey

A Pouch Lamprey, Geotria australis. Source: Rudie H. Kuiter / Aquatic Photographics. License: All rights reserved


Primitive eel-like fishes with two dorsal fins near the tail, 7 pairs of pore-like gill openings and a mouth in the shape of an oral disc fringed with skin flaps and armed with many small, horny teeth.

Pouch Lampreys have cartilaginous skeletons, primitive eyes, a single median nostril. They lack true jaws, paired fins and scales. Breeding males have a large baggy pouch on the underside of the head.

These jawless fishes are anadromous - adults spawn in the headwaters of freshwater rivers and streams, and when the larvae or ammocoetes hatch, they drift downstream and burrow into soft muddy sediments. They spend the next few years filter-feeding on micro-organisms from the water above.

After metamorphosis, young adults migrate downstream to estuaries and coastal waters, where they feed parasitically by rasping flesh from other fishes with their toothy tongues. They eventually cease feeding and migrate back to freshwater to breed.

Video of Pouched Lamprey in south Western Australia

Cite this page as:
Dianne J. Bray & Martin F. Gomon, Geotria australis in Fishes of Australia, accessed 21 Jan 2018, http://fishesofaustralia.net.au/home/species/3415

Pouch Lamprey, Geotria australis Gray 1851

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Widespread throughout cold temperate waters of the Southern Hemisphere, from South America, Australia and New Zealand. In Australian waters, Pouched Lampreys live in marine, estuarine and coastal rivers and streams on the south coast, from about Lakes Entrance, Victoria, to Perth, Western Australis.

They have an anadromous life cycle. Adults spawn in freshwater, and the worm-like ammocoete larvae live in muddy burrows in the upper reaches of coastal streams for about 4 years. As young adults, the lampreys migrate downstream and spend about two years in the Southern Ocean, before returning to breed in freshwater.


Body eel-like with 7 pore-like gill openings and a single median nostril on top of the head. The mouth lacks jaws, and is modified into an oral disc with many blunt, overlapping, flat, horny teeth in curved rows and several larger central teeth. The oral disc is fringed by short, fleshy papillae. Mature males have an enlarged oral disc and sometimes a baggy pouch beneath the head. Two dorsal fins are set well back near the tail, the first short-based and the second slightly longer, ending near the origin of caudal fin. Scales, pectoral, ventral and anal fins are absent. The ammocoetes (<12cm) lack eyes and have a single undivided dorsal fin.


Ammocoete larvae to 10cm; adults to 60cm TL.


Adults are dark brown to grey, and the ammocoetes are brown. Young adults at sea are silver or silvery cobalt blue, with two greenish or blue-green dorsal stripes.


The larvae or ammocoetes begin their life as filter feeders, living mostly on detritus and microscopic algae. After metamorphosis, southern lampreys become parasitic. They use their sucker-like mouth and horny rasping teeth to attach to other fishes and tear into the flesh of their prey. Adults stop feeding when they return to freshwater rivers to spawn, surviving on stored fats and body tissues during their migration.


Newly hatched ammocoete larvae drift downstream and eventually burrowing into muddy substrates. After 4-5 years, the ammocoetes metamorphose into young adult lampreys over a period of about six months. During this time their eyes become larger and develop the visual pigments essential for life at sea. They migrate downstream, leaving behind their life as filter-feeders to become parasites on other fishes.

They spend the next two years or so in the Southern Ocean before undertaking a long migration of up to 18 months back to the headwaters of freshwater streams to breed. Remarkably, the lampreys do not feed during this time. Once in freshwater, they lose their brilliant colour, becoming a drab brown. Males may also develop the large characteristic pouch on the underside of the head behind the mouth.

Adults usually spawn in small, shallow, gravel-bottomed streams. The female prepares a small depression or nest in the substrate and attaches herself to a rock with her oral disc. The male attaches to the female with his oral disc and wraps around her to squeeze out her eggs before releasing his sperm. Adults die shortly after spawning.


When lampreys migrate upstream to spawn they must often negotiate obstacles such as rapids, waterfalls and even dams. Pouched lampreys are able to climb structures by gripping onto rocks and other surfaces with their sucking mouths, gradually inching their way upstream. They can even move around oover round to make their way upstream.

Species Citation

Geotria australis Gray 1851, List fish Brit. Mus. Part I: 142, Pl. 1 (fig. 3), Pl. 2. Type locality: Hobson’s Bay or Onkaparinga, SA.


Dianne J. Bray & Martin F. Gomon

Pouch Lamprey, Geotria australis Gray 1851


Allen, G.R. 1989. Freshwater fishes of Australia. T.F.H. Publications, Inc., Neptune City, New Jersey.

Allen, G.R., S.H. Midgley & M. Allen. 2002. Field guide to the freshwater fishes of Australia. Western Australian Museum, Perth, Western Australia. 394 p.

Bird, D.J. & Potter, I.C. 1983. Proximate composition at various stages of adult life in the Southern Hemisphere lamprey, Geotria australis Gray. Comp. Biochem. Physiol. 74 A(3): 623-633.

Cadwallader, P.L. & G.N. Backhouse. 1983. A guide to the freshwater fish of Victoria. Victoria Government Printing Office. Melbourne: 1-249.

Chilcott, S.J. & P. Humphries. 1996. Freshwater fish of northeast Tasmania with notes on the dwarf galaxias. Records of the Queen Victoria Museum 103: 145-149.

Collin, H.B. & S.P. Collin. 2000. The corneal surface of aquatic vertebrates: microstructures with optical and nutritional function? Phil. Trans. R. Soc. Lond. B 355(1401): 1171-1176.

Collin, S.P., Hart, N.S., Shand, J. & Potter, I.C. 2003. Morphology and spectral absorption characteristics of retinal photoreceptors in the southern hemisphere lamprey (Geotria australis). Vis. Neurosci. 20(2): 119-130.

Collin, S.P., Potter, I.C. & Braekevelt, C. (1999) The ocular morphology of the southern hemisphere lamprey Geotria australis Gray, with special reference to the characterisation and phylogeny of photoreceptor types. Brain Behav. Evol. 54: 96-118.

Cook, R.D., I.C. Potter & R.W. Hilliard. 1990. Morphology and innervation of the buccal glands of the Southern Hemisphere lamprey, Geotria australis. J. Morphol. 206(1): 133-145.

Davies, W.L., Collin, S.P. & Hunt, D.M. 2009. Adaptive gene loss reflects differences in the visual ecology of basal vertebrates. Molecular Biology and Evolution 26(8): 1803-1809.

Davies, W., Cowing, J., Carvalho, L., Potter, I., Trezise, A., Hunt, D. & Collin, S. 2007. Functional characterization, tuning, and regulation of visual pigment gene expression in an anadromous lamprey. FASEB J. 21: 2713–2724.

Fernholm, B. 1990. Petromyzontidae. p. 79-80. In O. Gon and P.C. Heemstra (eds.) Fishes of the Southern Ocean. J.L.B. Smith Institute of Ichthyology, Grahamstown, South Africa. 462 pp.

Fletcher, L.N., Coimbra, J.P., Rodger, J., Potter, I.C., Gill, H.S., Dunlop, S.A. & Collin, S.P. 2014. Classification of retinal ganglion cells in the southern hemisphere lamprey Geotria australis (Cyclostomata). Journal of Comparative Neurology 522(4): 750-771.

Galloway, R., Potter, I.C., Macey, D.J. & Hilliard, R.W. 1987. Oxygen consumption and responses to hypoxia of ammocoetes of the Southern Hemisphere lamprey Geotria australis. Fish Physiology and Biochemistry 4(2): 63-72.

Gill, H.S., Renaud, C.B., Chapleau, F., Mayden, R.L. & Potter I.C. 2003. Phylogeny of living parasitic lampreys (Petromyzontiformes) based on morphological data. Copeia 2003(4): 687-703.

Gomon, M.F., D.J. Bray & R.H. Kuiter. 2008. Fishes of Australia's Southern Coast. Reed New Holland. Chatswood, Australia.

Gray, J.E. 1851. List of the specimens of fish in the collection of the British Museum. Part I, 160 pp.

Gustafsson, O.S.E., Collin, S.P. & Kröger, R.H.H. 2008. Early evolution of multifocal optics for well-focused colour vision in vertebrate.s. J. Exp. Biol. 211: 1559-1564.

Hammer, M.P. & K.F. Walker. 2004. A catalogue of South Australian freshwater fishes, including new records, range extensions and translocations. Transactions Royal Society of South Australia 128(2): 85-97.

Hardisty, M.W. & Potter, I.C. 1971. The general biology of adult lampreys. In : Hardisty, M.W. & Potter, I.C. (eds.) The Biology of Lampreys Vol. 1 (Academic Press : London)

Hardisty, M.W., Potter, I.C. & Hilliard, R.W. 1986. Gonadogenesis and sex differentiation in the Southern Hemisphere lamprey, Geotria australis Gray. J. Zool. Lond. (A) 209: 477-499.

Hubbs, C.L. & Potter, I.C. 1971. Distribution, phylogeny and taxonomy. pp. 1-65 figs 1-112 in Hardisty, M.W. & Potter, I.C. (eds). The Biology of Lampreys. London : Academic Press Vol. 1

Jellyman, D.J. & Glova, G.J. 2002. Habitat use by juvenile lampreys (Geotria australis) in a large New Zealand river. New Zealand Journal of Marine and Freshwater Research 36: 503–510.

Kelso, J.R.M. 1993. Substrate selection by Geotria australis ammocoetes in the laboratory. Ecology of Freshwater Fish 2: 116–120.

McDowall, R.M. 1988. Diadromy in fishes: migrations between freshwater and marine environments. Croom Helm, London.

Macey, D.J., Cake, M.H. & Potter, I.C. 1988. Exceptional iron concentrations in larval lampreys (Geotria australis) and the activities of superoxide radical detoxifying enzymes. Biochemical Journal 252(1): 167-172.

Merrick, J. & Schmida, G. 1984. Australian Freshwater Fishes. Macquarie University, North Ryde, NSW.

Morgan, D.L., H.S. Gill & I.C. Potter. 1998. Distribution, identification and biology of freshwater fishes in south-western Australia. Records of the Western Australian Museum Supplement 56: 1-97.

Nelson, J.S. 2006. Fishes of the World. Hoboken, New Jersey : John Wiley & Sons, Inc. 601 pp.

Paxton, J.R., J.E. Gates & D.F. Hoese. 2006. Petromyzontidae, pp. 42-44. In : Beesley, P.L. & A. Wells. Zoological Catalogue of Australia. Volume 35. ABRS and CSIRO Publishing, 3 vols.

Potter, I.C. 1986. The distinctive characters of southern hemisphere lampreys (Geotriidae and Mordaciidae). pp. 9-29 in Uyeno, T., Arai, R., Taniuchi, T. & Matsuura, K. (eds). Indo-Pacific Fish Biology. Proceedings of the Second International Conference on Indo-Pacific Fishes. Tokyo : Ichthyological Society of Japan 985 pp.

Potter, I.C., Hilliard, R.W. & Bird, D.J. 2009. Metamorphosis in the Southern Hemisphere lamprey, Geotria australis. Journal of Zoology 190: 405–430.

Potter, I.C., Macey, D.J., Roberts, A.R. & Withers, P.C. 1996. Oxygen consumption by ammocoetes of the lamprey Geotria australis in air. Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 166(5): 331-336.

Potter, I., Prince, P & Croxall, J. 1979. Data on the adult marine and migratory phases in the life cycle of the southern hemisphere lamprey Geotria australis. Environ Biol Fishes 4: 65–69.

Potter, I.C. & Strahan, R. 1968. The taxonomy of lampreys Geotria and Mordacia and their distribution in Australia. Proceedings of the Linnean Society of London 179(2): 229-240 figs 1-2.

Robinson, E.S. & G.C. Potter. 1981. The chromosomes of the southern hemispheric lamprey, Geotria australis Gray. Experientia 37(3): 239-240.

Schwab, I.R. & S.P. Collin. 2005. Are you calling me primitive? British Journal of Ophthalmology 89: 1553.

Strahan, R. 1980. Family Mordaciidae: short-headed lampreys; Family Geotriidae: pouched lamprey. pp. 38-43 6 figs in McDowall, R.M. (ed.). Freshwater Fishes of South-eastern Australia. Sydney : A.H. & A.W. Reed 208 pp. figs

Yamazaki, Y. & A. Goto. 2000. Present status and perspectives on the phylogenetic systematics and speciation of lampreys. Japanese Journal of Ichthyology 47(1): 1-28.

Quick Facts

CAAB Code:37003001


Biology:Primitive jawless fishes

Feeding:Parasitic carnivore

Habitat:Freshwater, marine

Max Size:60 cm TL

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