Dwarf blackfish

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Dwarf blackfish
Okefenokee dwarf blackfish (Elassoma okefenokee)

Okefenokee dwarf blackfish ( Elassoma okefenokee )

Systematics
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Sunfish-like (Centrarchiformes)
Family : Elassomatidae
Genre : Dwarf blackfish
Scientific name of the  family
Elassomatidae
Jordan , 1877
Scientific name of the  genus
Elassoma
Jordan, 1877

The dwarf blackfish ( Elassoma ) are a genus of very small North American freshwater fish from the group of perch relatives (Percomorphaceae). The genus is monotypical in the family Elassomatidae , which was separated from the family of sunfish (Centrarchidae). They live in the southeastern United States of America , including the Mississippi basin . Etymologically, Elassoma is a haplology for elassosoma "smaller body".

features

They are small fish, 33 to 47 mm long, depending on the species, with a bluish black or brown color. Dwarf blackfish have five gill spines , a single dorsal fin and a rounded caudal fin, but no lateral line organ on the body. Your scales are cycloid . The sexes also differ in the teeth of the jaws outside of the breeding season. In the males the entire upper jaw is occupied with strong teeth, while in the females the upper jaw is only occupied with smaller teeth in the middle.

Basically, dwarf blackfish differ from sun bass in their small stature, their continuous dorsal fin and their courtship behavior.

Reproduction

Little blackfish show pronounced sexual dimorphism during the breeding season . While the males enhance their dark, contrasting drawing elements, the females remain simple, colored in inconspicuous brown tones.

The males are then territorial and courtship with flapping movements of the fins and move the body up and down in waves. It finally spawns in a dense network of plants, usually 20 to 30 centimeters above the bottom of the water. Brood care does not take place. The fish spawn several times at intervals of a few days to a few weeks. The approximately 60 to 80 eggs of a spawning act are released in individual portions of approximately six to ten pieces, each of which is surrounded by a thick jelly shell. The individual eggs are very small and crystal clear. The fry hatch after two to three days and hang on to plants for a few days with an adhesive thread on their heads before they become free swimming.

Systematics

In the 1980s and before that, the dwarf blackfish were placed in the sunfish (Centrarchidae) and referred to as dwarf sunfish or as a separate family but as close relatives of the sunfish. Both families were traditionally assigned to the perch-like (Perciformes) and even classified into different sub-orders within the perch-like. However, new molecular biological studies show that sunfish and dwarf blackfish are closely related and sister groups , while they are only distantly related to the perch (Percidae). The team of ichthyologist Thomas J. Near and that of fish systematic specialist Ricardo Betancur-R. therefore assigned sunfish and black bass to the Centrarchiformes order established by the German-Dutch zoologist Max Carl Wilhelm Weber and the Dutch biologist Lieven Ferdinand de Beaufort and named after the sunfish in the 19th century .

species

7 species are currently known:

swell

  1. ↑ a b c Joseph S. Nelson : Fishes of the World , John Wiley & Sons, 2006, ISBN 0-471-25031-7
  2. ^ Greek dictionary W. Pape 1880
  3. ↑ a b Uwe Werner: A dwarf black perch with a signal effect . in DATZ 4/2009, ISSN  1616-3222
  4. ^ A b Bohlen J. & A. Nolte: On the reproductive biology of the dwarf black perch . in Riehl, R. & H. Greven: Reproductive biology of aquarium fish Volume 2, Schmettkamp-Verlag, Bornheim, page 69-78 (1999) online at www.joerg-bohlen.de ( Memento of the original from January 17, 2005 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.joerg-bohlen.de
  5. ↑ Thomas J. Near, Michael Sandel, Kristen L. Kuhn, Peter J. Unmack, Peter C. Wainwright, Wm. Leo Smith: Nuclear gene-inferred phylogenies resolve the relationships of the enigmatic Pygmy Sunfishes, Elassoma (Teleostei: Percomorpha). Molecular Phylogenetics and Evolution 63 (2012) 388-395, doi : 10.1016 / j.ympev.2012.01.011
  6. ^ Thomas J. Near, A. Dornburg, RI Eytan, BP Keck, WL Smith, KL Kuhn, JA Moore, SA Price, FT Burbrink, M. Friedman & PC Wainwright. 2013. Phylogeny and tempo of diversification in the superradiation of spiny-rayed fishes. Proceedings of the National Academy of Sciences of the United States of America. 101: 12738-21743. doi: 10.1073 / pnas.1304661110 , PDF
  7. ↑ Ricardo Betancur-R, Edward O. Wiley, Gloria Arratia, Arturo Acero, Nicolas Bailly, Masaki Miya, Guillaume Lecointre and Guillermo Ortí: Phylogenetic classification of bony fishes . BMC Evolutionary Biology, BMC series - July 2017, DOI: 10.1186 / s12862-017-0958-3
  8. ↑ Elassoma on Fishbase.org (English)

Web links

Commons : Black Bass  - Collection of images, videos, and audio files