Dendrogramma enigmatica

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Dendrogramma enigmatica
Holotype of Dendrogramma enigmatica

Holotype of Dendrogramma enigmatica

Systematics
Trunk : Cnidarians (Cnidaria)
Class : Hydrozoa (Hydrozoa)
Order : State jellyfish (Siphonophorae)
Family : Rhodaliidae
Genre : Dendrogramma
Type : Dendrogramma enigmatica
Scientific name of the  genus
Dendrogramma
Just et al., 2014
Scientific name of the  species
Dendrogramma enigmatica
Just et al., 2014

Dendrogramma enigmatica is a species from the order of the state jellyfish (Siphonophorae). Their scientific generic name refers to thebranching of the digestive tract, similar toa dendrogram . The type epithet enigmatica refers to the puzzling systematic positionwhen it was discovered.

description

State jellyfish consist of sticks of specialized individual animals, whereby only the originally found elements of Dendrogramma enigmatica , which are probably cover pieces, and a single orange, gas-filled sack, which probably represents a pneumatophore (swimming buoy), are known.

The originally found elements consist of a cylindrical stem and a disc spread out at its end, so that they resemble the fruiting body of an umbrella mushroom . A simple round mouth opening is at the end of the stem facing away from the umbrella and probably creates the connection to the entire stick. From here the gastric space extends as a tube to the screen, where it branches dichotomously . The epidermis consists of a layer of flat cells of the same type except in the oral cavity, where they are thickened and apparently with vacuoles . The gastrodermis consists of a layer of elongated cells containing vacuoles. In the first description, two types of these elements were described as two types, which, according to genetic analysis, belong to the same species: In the case of the elements described as Dendrogramma enigmatica , the stem is relatively long in relation to the diameter of the umbrella (in the case of the holotype about 7.8 to 11 Millimeters), its length corresponds approximately to its one and a half times its diameter at the transition to the screen. The screen has a notch and, in holotype 37, branches of the gastric space. The mouth opening is surrounded by two lobes of different sizes. In "Dendrogramma discoides" the stem is short compared to the diameter of the umbrella (with the holotype about 4.5 to 17 millimeters) and also shorter than its diameter at the umbrella base. The umbrella is entire and the mouth opening is surrounded by two equally large and one significantly smaller lobes. The number of gastric space branches in the screen is 63.

Research history

Dendrogramma enigmatica was first collected in 1986 at a depth of 400 to 1000 meters off the south-east Australian continental slope and later examined at the Museum Victoria in Melbourne . The exact systematic position of the animals was initially unknown and it was speculated that they could represent a previously unknown tribe or living relatives only from the Ediacara fauna of known organisms. Later molecular biological investigations on fresh material made it possible to classify it as a state jellyfish.

literature

  • Jean Just, Reinhardt Møbjerg Kristensen, Jørgen Olesen: Dendrogramma, New Genus, with Two New Non-Bilaterian Species from the Marine Bathyal of Southeastern Australia (Animalia, Metazoa incertae sedis) - with Similarities to Some Medusoids from the Precambrian Ediacara . In: PLoS One . tape 9 , no. 9 , 2014, p. e102976 (English, full text [PDF]).
  • Timothy D. O'Hara, Andrew F. Hugall, Hugh MacIntosh, Kate M. Naughton, Alan Williams, Adnan Moussalli: Dendrogramma is a siphonophore . In: Current Biology . tape 26 , no. 11 , 2016, p. 457-458 (English).

Web links

Commons : Dendrogramma  - collection of images, videos and audio files