Ear fish

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Ear fish
Kneria uluguru

Kneria uluguru

Systematics
Overcohort : Clupeocephala
Cohort : Otomorpha
Sub-cohort : Ostariophysi
Order : Sandfish (Gonorynchiformes)
Family : Slender fish (Kneriidae)
Genre : Ear fish
Scientific name
Kneria
Steindachner , 1866

The ear fish ( Kneria ) are a genus of small freshwater fish that occur in Africa south of the equator . The main areas of distribution are the Congo Basin , Katanga , Tanzania and Angola . The genus was named in honor of the Austrian zoologist and ichthyologist Rudolf Kner .

features

Ear fish are elongated, spindle-shaped fish and grow to be 4.8 cm to 7.5 cm long. Their body shape is reminiscent of that of loaches , but the body is flatter than that of most loaches and the caudal stalk is longer. The mouth is slightly below and strongly protractile (can be extended), the margin of the upper jaw is formed only by the premaxillary . The jaw and palate are edentulous. The dorsal and anal fins are short, the caudal fin is forked. The dorsal fin attachment is above or behind the ventral fin attachment. The intestine is very long and the swim bladder is connected to it ( physostomes ). The lateral line bends down behind the pelvic fins and then runs below the lateral center line. A bulging of the upper gill space, the suprabranchial organ , enables the fish to breathe atmospheric oxygen. Kneria species are inconspicuously colored in various shades of brown.

Occipital organ

The bean- or ear-shaped occipital organ in front of and above the pectoral fin attachment, which all adult males have, is typical of the species and a specialty of fish. The organ consists of two parts: the opercular organ, a round area formed as a suction cup on the gill cover and the postopercular organ above the pectoral fins, which consists of a zone with transverse cornified skin ridges, is delimited at the top by another, crescent-shaped skin ridge and is open at the bottom . The occipital organ serves as an adherent organ in courtship and spawning. The males probably attach themselves laterally to the females with its help. How exactly this happens and what function the postopercular organ has is unknown, since the attachment happens so quickly that it cannot be observed with the naked eye.

Way of life

The way of life of the ear fish is still largely unknown. They are more or less flow-loving (rheophil), soil-oriented and mainly eat growth (algae) and / or the invertebrates that live between the algae. They are able to move their head to the right and left and upwards.

Types and occurrences

There are 13 types that are difficult to distinguish from one another. In some species the for accurate overlap determining important characteristics and may have been to many types described .

literature

  • Günther Sterba : The world's freshwater fish. 2nd Edition. Urania, Leipzig / Jena / Berlin 1990, ISBN 3-332-00109-4 .
  • Günther Sterba (Ed.), Gert Brückner: Encyclopedia of Aquaristics and Special Ichthyology. Neumann-Neudamm, Melsungen u. a. 1978, ISBN 3-7888-0252-9 .
  • Lothar Seegers: The Kneriden East and Central Africa, The genus Kneria. Pages 585 to 590, in DATZ The Aquarium and Terrarium Magazine; 9/1996, Verlag Eugen Ulmer , ISSN  1616-3222 .

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