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  • A lamprey / Piharau (Geotria australis) underwater.
    Rights: Peter Anderson, Department of Conservation Te Papa Atawhai, Creative Commons 4.0 Published 14 December 2017 Size: 4.3 MB Referencing Hub media

    The lamprey (Geotria australis) belongs to is a primitive order1 of jawless fish (Petromyzontiformes). The adults are good climbers and can scale waterfalls, but because of habitat2 loss and dams blocking their migrations, most populations3 now occur at lower altitudes (less than 400 m) closer to the coast.

    Lamprey juveniles (ammocoetes) live in burrows in silty river edges. As ammocoetes, lamprey are blind and browny-black in colour. Once they reach 100–120 mm (after 3–5 years’ growth), they metamorphose into the adult form, which contains eyes and a vibrant blue colouration. This stage is termed macropthalmia, and these fish will migrate out to sea to feed parasitically on fish and whales.

    Lampreys are anadromous – this means they migrate up rivers from the ocean to spawn4. The eggs hatch in freshwater where juveniles reside for up to 4 years before heading out to the open ocean. Here, they attach onto the gills and flesh of other fish and marine mammals and live as parasites5. They use their specially adapted6 mouth – a roundish sucker, armed within by series of rasping teeth, with sharper and stronger ones on the tongue – to feed on the host7 animal’s blood.

    Before reaching sexual maturity, the lamprey returns to freshwater to breed and can use its circular sucker to latch onto and surmount obstacles such as rapids and small falls.

    The returning adult lamprey spends up to 18 months inland, maturing sexually before spawning8. Both sexes will survive spawning for over 3 months before dying. Scientists discovered the first Geotria australis spawning sites in the southern hemisphere on Canterbury's Banks Peninsula.

    The adults do not feed in freshwater – so other freshwater fish and people wading in streams will not be preyed on!

    Lamprey – also called kanakana or piharau – are a taonga species9 and were considered a delicacy by Māori.

    Watch a lamprey using its sucker mouth to climb a wall in this video.

    Acknowledgement: Peter Anderson, Department of Conservation Te Papa Atawhai, Creative Commons 4.0

    1. order: A classification grouping that ranks above family and below class (kingdom > phylum > class > order > family > genus > species).
    2. habitat: The natural environment in which an organism lives.
    3. population: In biology, a population is a group of organisms of a species that live in the same place at a same time and that can interbreed.
    4. spawn: The act of reproduction of aquatic creatures such as fishes, amphibians, crustaceans and mollusks. The mixing of the sperm of a male and the eggs of a female of the species. In mycology, the mycellium of mushrooms.
    5. parasite: An organism that lives in or on another organism. Parasites usually cause harm to their host organism.
    6. adaptation: A change in the structure or function of something. In biology, a change in a species, as a result of natural selection. Individuals with a particular feature (adaptation) are more likely to survive and reproduce than individuals without this feature.
    7. host: An organism that contains a parasite or other dependent organism. Hosts usually provide the dependent organism with food and shelter.
    8. spawning: The laying of eggs by aquatic animals like fish, frogs, crustaceans or mollusks.
    9. taonga species: Species or biota that are of value to Māori or hold cultural significance to Māori, which may include introduced species.
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      order

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    2. A classification grouping that ranks above family and below class (kingdom > phylum > class > order > family > genus > species).

      spawn

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    4. The act of reproduction of aquatic creatures such as fishes, amphibians, crustaceans and mollusks. The mixing of the sperm of a male and the eggs of a female of the species. In mycology, the mycellium of mushrooms.

      host

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    6. An organism that contains a parasite or other dependent organism. Hosts usually provide the dependent organism with food and shelter.

      habitat

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    8. The natural environment in which an organism lives.

      parasite

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    10. An organism that lives in or on another organism. Parasites usually cause harm to their host organism.

      spawning

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    12. The laying of eggs by aquatic animals like fish, frogs, crustaceans or mollusks.

      population

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    14. In biology, a population is a group of organisms of a species that live in the same place at a same time and that can interbreed.

      adaptation

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    16. A change in the structure or function of something. In biology, a change in a species, as a result of natural selection. Individuals with a particular feature (adaptation) are more likely to survive and reproduce than individuals without this feature.

      taonga species

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    18. Species or biota that are of value to Māori or hold cultural significance to Māori, which may include introduced species.