Short-headed lamprey facts for kids
Quick facts for kids Short-headed lamprey |
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| Conservation status | |
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Not evaluated (IUCN 3.1)
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| Scientific classification | |
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Mordaciidae
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| Genus: |
Mordacia
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M. mordax
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| Mordacia mordax (J. Richardson, 1846)
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The short-headed lamprey, also called the Australian lamprey or Murray lamprey, is a special type of lamprey found in south-eastern Australia and Tasmania. Its scientific name is Mordacia mordax. This lamprey belongs to a family called Mordaciidae, which has three species: M. praedox, M. mordax, and M. lapicida.
The short-headed lamprey is a rare animal that feeds on other fish. It's part of a very old group of animals that don't have jaws, just like hagfish. These jawless animals are important for understanding how vertebrates (animals with backbones) have changed over millions of years. The short-headed lamprey looks a bit like an eel. It has a thin body that can grow up to 50 centimeters long. It has two small fins on its back, and its skin is usually blue-gray or brown. Its eyes are small and located on the top of its head.
How Lampreys Evolved
Animals without jaws, like lampreys, have been around for about 500 million years! They are a key group for scientists studying how animals with backbones have changed over time. Even though the short-headed lamprey lives near another lamprey family in the Southern Hemisphere called Geotriidae, they are quite different.
Scientists have studied proteins like insulin from both groups. They found that the insulin in M. mordax is very different from that in Geotria australis (the only species in Geotriidae). There are 18 differences in their insulin, but only four differences when compared to lampreys from the Northern Hemisphere. This suggests that the Southern Hemisphere lampreys probably separated from each other a very long time ago in terms of evolution. It also seems that the Geotriidae family and the Northern Hemisphere lampreys (Petromyzontidae) are more closely related to each other than either is to any Mordacia species.
Lamprey Behavior and Life Cycle
Adult short-headed lampreys are parasites, meaning they attach to and feed on other fish. They are also anadromous. This means they live in the ocean but travel to fresh water to breed. They migrate up rivers in south-eastern Australia, from the Shoalhaven River in New South Wales all the way to Gulf St Vincent in South Australia.
Baby lampreys, called ammocoetes or larvae, stay in fresh water. They eat tiny organisms called plankton. After about three to four years, they go through big changes in their bodies. These changes allow them to switch from eating plankton to feeding on larger fish. After this change, they migrate to the South Pacific and Southern Oceans. Adult lampreys can travel hundreds of miles in the ocean to feed. Once they are fully grown and ready to reproduce, they return to freshwater rivers, lay their eggs, and then they die.
Lamprey Body Features
Young short-headed lampreys (larvae) can be anywhere from 20 to 150 millimeters long, depending on how much they have grown. When they are fully developed, they usually measure between 300 and 420 millimeters. As they grow, their teeth change a lot. They start with teeth that are all connected, but as they get older, these teeth separate and become individual, pointed teeth. This is different from the other Southern Hemisphere lamprey, Geotria australis, which has flat, rounded teeth.
The eyes of the short-headed lamprey are unique. They are located on the top and sides of its head, which is different from other lamprey species. Their eyes have special cells that help them see better in the dark. This is similar to how deep-sea fish eyes work. This is useful because M. mordax only comes out of the river sediment at night to travel.
The fins on the back of the short-headed lamprey are also special. Its front and back dorsal fins are connected to its tail fin. When M. mordax is fully grown, these front and back dorsal fins are clearly separated, which helps tell them apart from Northern Hemisphere lampreys.
Scientists often study lampreys to learn more about how the bodies of animals with backbones develop. For example, some studies have shown that lampreys have similar types of fats (lipoproteins) in their bodies as humans do. Lampreys are also the simplest animals with backbones that show clear roles for special chemicals called neurohormones in controlling their reproduction.
