Spiny eels

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Spiny eels
Mastacembelus armatus

Mastacembelus armatus

Systematics
Sub-cohort : Neoteleostei
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Gill slit eels (Synbranchiformes)
Family : Spiny eels
Scientific name
Mastacembelidae
Bleeker , 1870

The spiny eels (Mastacembelidae), also known as arrow eels , live with almost 90 species in tropical and subtropical fresh waters of the Old World. Some spiny eel species are caught as food fish. Smaller or particularly colored species are often found in the aquarium fish trade.

distribution

They live from the Euphrates and Tigris river basin ( Mastacembelus mastacembelus ) across India and Southeast Asia to southern China. In Africa they occur in the Congo , the Upper Zambezi , Okavango , Lake Malawi and Lake Victoria . In the East African Lake Tanganyika there are 13 endemic species that form a monophyletic swarm of species that arose in the course of adaptive radiation . Some of the Asian species also go into brackish water . There are a total of 39 species in Asia and 48 in Africa.

Appearance

Spiny eels have an eel-like, sometimes ribbon-shaped, elongated body. The largest spiny eel is the fire spiny eel ( Mastacembelus erythrotaenia ), which reaches a length of one meter, while the tiny Caecomastacembelus latens from the rapids of the lower Congo is only seven centimeters long. For most of them, the body is 15 to 20 times as long as the height. Some species are significantly more stocky and only 6 to 7 times as long as their body is tall. In contrast to real eels, they have short dorsal and anal fin spines, which, however, are usually not connected by a fin membrane. Ventral fins are missing. The caudal fin can be fused with the dorsal and anal fin. The fish are benthic and nocturnal, their eyes are weak, some are practically blind - the sense of smell is very well developed for this.

It is characteristic that the "upper lip" with the front nostrils is extended to form a trunk-like appendage (hence the name: from ancient Greek μάσταξ mástax 'mouth, beak, upper lip', ἐν- en- 'one' and βέλος bélos 'thrown' - So, for example, 'fish that moves the upper lip forward, the trunk sticks in where') - the premaxillary cannot be extended, the muscle responsible for it moves the "trunk" and its cartilaginous axis. The rear narins (nostrils) are in front of the eyes. The ectopterygoid steers with the prefrontal, a very unusual articulation. Premaxillaries and dentals are finely toothed. The gill openings are united ventrally, similar to the related gill slit eels (Synbranchidae). The gill arches are of the barbel type (Regan 1912). The shoulder girdle is far removed from the occiput. 66 to 110 vertebrae.

Fins formula : Dorsal IX-XXXXII / 52-131, Anal II-III / 30-130, caudal 19, pectoral 22nd

behavior

All spiny eels prefer heavily overgrown regions of their living waters, the species in the largely vegetation-free East African great lakes hide between stones. They are nocturnal. The eel-shaped species usually spend the day buried in the ground, while the ribbon-shaped species hide between aquatic plants. At least species that survive buried dry seasons are then air breathers . Spiny eels feed on worms, small crustaceans and small fish.

Reproduction

The reproductive behavior of the spiny eels is known in some species from observations in aquariums. The belted spiny eel ( Macrognathus circumcinctus ), a species that lives in fast-flowing waters, spawns in the river gravel, the strongly sticky eggs stick to it. The eye spot spiny eel ( Macrognathus aculeatus ) spawns as free-spawners near the surface of the water. The young fish stay near the bottom.

External system

The spiny eels belong to the order of the gill-slit-like (Synbranchiformes). Sister group of the spiny eels are the tiny, worm-like Chaudhuriidae , with which they are united in the suborder Mastacembeloidei. This is a sister group of the rest of the Synbranchiformes, i.e. the common clade of gill-slit eels (Synbranchidae) and spiked-tube mouths (Indostomidae). The sagitta , an otolith in the fish's ear, corresponds to that of the perch-like and shows that the spiny eels and all gill-slit eels belong to the perch relatives (Percomorphaceae).

Internal system

The spiny eels were divided by RA Travers into two subfamilies, the Afromastacembelinae with the genera Afromastacembelus and Caecomastacembelus to which the African species belong whose tail has grown together with the dorsal and the anal fin and the Mastacembelinae with the genera Macrognathus , Mastacembelus and Sinobdella , which include Asian species with isolated caudal fin. However, this system has not prevailed, since these genera do not correspond to any monophyletic groups, and the genera Afromastacembelus and Caecomastacembelus are regarded as synonyms of Mastacembelus .

Genera and species

Macrognathus aral
Indian pygmy eel
( Macrognathus pancalus )
Peacock spiny eel
( Macrognathus siamensis )
Zebra spiny eel
( Macrognathus zebrinus )
Fire spiny eel
( Mastacembelus erythrotaenia )
Macrognathus aculeatus ,
Mastacembelus unicolor ,
Mastacembelus zebrinus ,
Mastacembelus pancalus .

literature

  • Joseph S. Nelson : Fishes of the World . John Wiley & Sons, 2006, ISBN 0-471-25031-7
  • WA Gosline (1983): The relationships of the Mastacembelid and Synbranchid fishes. Yep J. Ichthyol. 29: 323-328.

Individual evidence

  1. ↑ Mastacembelus mastacembelus on Fishbase.org (English)
  2. ↑ a b c d Katherine J. Brown, Lukas Rüber, Roger Bills & Julia J. Day: Mastacelembelid eels support Lake Tanganyika as an evolutionary hotspot of diversification. BMC Evolutionary Biology, 2010, 10: 188, doi: 10.1186 / 1471-2148-10-188
  3. ^ William K. Gregory: Fish skulls. A study of the evolution of natural mechanisms. New York Zool. Soc. New York 1933, OCLC 251016995 . (1959 edition on archive.org)
  4. ↑ Peter Bucher: zoo animal keeping 5. Fish. German Harri GmbH, 2005, ISBN 3-8171-1352-8
  5. ^ RA Travers (1984): A review of the Mastacembeloidei, a suborder of synbranchiform fishes. Part I: Anatomical descriptions. Bull. Br. Mus. Nat. Hist. (Zool.) 46: 1-133.

Web links

Commons : Mastacembelidae  - Collection of images, videos and audio files