Protanguilla palau
| Protanguilla palau | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Protanguilla palau |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the family | ||||||||||||
| Protanguillidae | ||||||||||||
| Johnson , Ida & Miya , 2012 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Protanguilla | ||||||||||||
| Johnson, Ida & Miya , 2012 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Protanguilla palau | ||||||||||||
| Johnson , Ida & Sakaue , 2012 |
Protanguilla palau is a species of fish that is at the base of today's eel-like species and, in addition to features of today's eels, also has features that are otherwise only found in Cretaceous species or even earlier. It is therefore considered a living fossil . The species wasdiscoveredin an underwater cave off Palau in 2009.
features
Protanguilla palau is elongated, with a cylindrical front trunk, which is moderately flattened behind and merges into a very flat tail. The animals examined so far were about four and a half to eight inches long. The muzzle is flattened. The opening of the gills is an oval tube with a short, fringed collar. The scales are small and oval. They cover the body in a wicker-like pattern, but are absent around the eyes, mouth and tip of the snout. The lateral line organ runs through 80 to 84 scales. The pectoral fins start in the lower third of the body and have 18 or 19 branched rays. Ventral fins are absent as in all recent eel-like species. The dorsal and anal fins extend over two-thirds of the length of the body and are fused with the caudal fin . The dorsal fin has 176 to 189, the anal fin 175 to 191 unbranched rays, the caudal fin ten.
Protanguilla palau shows a number of characteristics that either correspond to today's eel-like or Cretaceous representatives or are completely unique. In contrast to all other eel-like species today, but just like some of the Cretaceous representatives of the order, Protanguilla palau has an intermaxillary bone and a metapterygoid , and neither the Symplecticum and Os quadratum nor the upper hypuralia are fused. Just as with today's eel-like, but in contrast to Cretaceous representatives, the dorsal, caudal and anal fins are also fused in Protanguilla palau and an entopterygoid is missing. Characteristics that are even more original than those of all known present-day or fossil eel-like species are the presence of a gill trap and fewer than 90 vertebrae .
Occurrence
Protanguilla palau is only known from an underwater cave in Palau at a depth of 35 meters.
Systematic position
Due to the unique combination of characteristics, Protanguilla palau was placed in its own genus and family within the eel-like. Anatomical and molecular-biological comparisons indicate that the species as a sister group is opposed to all other eel-like species of today and separated from them about 220 million years ago at the transition from the Triassic to the Jurassic .
literature
- G. David Johnson, Hitoshi Ida, Jiro Sakaue, Tetsuya Sado, Takashi Asahida, Masaki Miya (2012): A 'living fossil' eel (Anguilliformes: Protanguillidae, fam. Nov.) From an undersea cave in Palau. In: Proceedings of the Royal Society B , 279 (1730): 934-943. doi : 10.1098 / rspb.2011.1289 (English)
Web links
- Protanguilla palau on Fishbase.org (English)
- Live animal video ( YouTube video)