Mordacia
| Mordacia | ||||||||||||
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Mordacia lapicida |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Mordaciidae | ||||||||||||
| Gill , 1893 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Mordacia | ||||||||||||
| Gray , 1851 |
Mordacia is a genus of lampreys (Petromyzontiformes) that occurs in three species in the southern hemisphere. Two species live in southeast Australia, one in southern Chile .
features
Adult animals reach a maximum length of 54 to 60 cm, while their Ammocoetes larvae reach a maximum length of 16 cm. Like all lampreys, the Mordacia species are elongated like an eel, have a jawless round mouth, a cartilage skeleton and a chorda dorsalis . They have two dorsal fins, the second of which has grown together with the caudal fin during the Ammocoetes stage and in isolated individuals of M. mordax . The cloaca is under the back half of the second dorsal fin. Scales and paired fins are missing. Adult animals have well-developed eyes. In animals that are almost fully grown and not yet sexually mature, they are more to the side, and in sexually mature animals they are more on the top of the head. The pocket-like gills are not supported by gill arches. The round mouth and tongue are covered with conical teeth. Uniform oral papillae are present on the lateral edges of the mouth, but are absent in front and behind. The digestive tract is equipped with cilia and spiral folds .
Way of life
The Ammocoetes larvae of the Mordacia species live for years as filter feeders in freshwater, where the non-parasitic Australian species Mordacia praecox also remains as an adult and spawns immediately after metamorphosis , while the other two species live as anadromous migratory fish and migrate into the sea after metamorphosis and attack other fish with their suckers and feed on the wound. The parasitic Mordacia species migrate into fresh water for reproduction . Their numerous, small and yolkless eggs are released through hard floors. The animals die after spawning.
species
- Mordacia lapicida (Gray, 1851)
- Mordacia mordax (Richardson, 1846)
- Mordacia praecox Potter, 1968
The two Australian species M. mordax and M. praecox form a pair of a parasitic and a non-parasitic species.
Systematics
The genus Mordacia was originally assigned to the Petromyzontidae as the only genus of the subfamily Mordaciinae . Today they are the only genus in the Mordaciidae family.
literature
- Joseph S. Nelson : Fishes of the World. John Wiley & Sons, New York 2006. ISBN 0-471-25031-7 .
- Claude B. Renaud: Lampreys of the world. An annotated and illustrated catalog of lamprey species known to date. - FAO Species Catalog for Fishery Purposes. No. 5. Rome, 2011. PDF