Turritopsis dohrnii

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Turritopsis dohrnii
Turritopsis dohrnii.jpg

Turritopsis dohrnii

Systematics
Class : Hydrozoa
Order : Anthomedusae
Subordination : Filifera
Family : Oceaniidae
Genre : Turritopsis
Type : Turritopsis dohrnii
Scientific name
Turritopsis dohrnii
( Weismann ), 1883

Turritopsis dohrnii is a Hydrozoen - Art from the genus Turritopsis in the family of oceaniidae . Due to peculiarities in their life cycle, the individuals of this species are potentially biologically immortal . The type of "immortal jellyfish" was previously classified as Turritopsis nutricula .

description

The living, colorless or pink polyp heads (hydrant) have 18 to 20 tentacles. The medusa of Turritopsis dohrnii are 2.7 millimeters high and 3.2 millimeters in diameter. The 14 to 32 tentacles are sometimes thickened at the terminal end. The ocelli (light sense organs) are rust-colored.

According to a study by Martell et al. Just released medusa have 8 tentacles, the tips of which are somewhat thickened. Other medusas had 11 or 12 tentacles. 16 tentacles, each with thickened tips, were counted on older animals. The small number of tentacles is typical of the species in the Mediterranean, the number of tentacles of all other Turritopsis species is higher. The discovery of an adult animal with 32 tentacles could never be confirmed later. All other finds had fewer than 24 tentacles, and 24 is too high to be common for Turritopsis dohrnii . In studies by Piraino et al. no more than 16 tentacles were counted in 4000 animals bred in the laboratory.

distribution

Turritopsis dohrnii is native to Italy and Mallorca , Turritopsis sp. (a separate species is unlikely, however) in southern Spain ( Alborán Sea , Mediterranean Sea ).

Life cycle

The fertilized eggs develop into a planula within a few days . Colony-forming polyps emerge from these on the sea floor and form new medusae through budding . After a few weeks (the exact duration depends on the sea temperature, at 20 ° C it is 25 to 30 days, at 22 ° C 18 to 22 days) these become sexually mature and can form new planulae when fertilized. In two related species ( Turritopsis polycirrha and T. rubra ) the eggs develop into the finished planula attached to the outer stomach wall (the manubrium) of the maternal medusa. T. polycirrha also has the special feature that it is hermaphroditic (hermaphroditic).

immortality

According to the usual life cycle of the cnidaria , the medusa die off after they have reproduced. In Turritopsis dohrnii , however, cells of the outer umbrella (exumbrella) can become the germ of a new polyp through transdifferentiation . This creates a new generation of polyps that emerge directly from the medusa and is genetically identical to it. The species is the first known case of a multicellular cell ( Metazoa ) in which the sexually mature individual reverts to a sexually immature, colony-forming life form. In this way an individual can go through the entire life cycle again and again and thus theoretically practice immortality. Recent taxonomic studies have shown that the Mediterranean specimens on which many of the studies were carried out are very likely to belong to the species Turritopsis dohrnii , which z. B. is characterized by a smaller number of tentacles. The Japanese forms of Turritopsis nutricula or dohrnii have the same ability to rejuvenate (rejuvenation).

Taxonomy

Turritopsis dohrnii was first described by Weismann in 1883 under the name Dendroclava dohrnii . The ending of the species addition dohrnii with -ii is correct, it is dedicated to Anton Dohrn , Latinized as Dohrnius, which results in dohrnii in the genitive . The first description was based only on the hydroid form. Neppi (1917) synonymized the species with Turritopsis nutricula , a view shared by almost all subsequent authors. The only life cycle studies by Piraino et al. (1996) and Carla et al. were also published under Turritopsis nutricula . Schuchert (2004) regards Turritopsis dohrnii as a different, separate species from Turritopsis nutricula . This view is supported by studies by Migotto (1996) and MP Miglietta.

literature

  • Jean Bouillon, Ferdinando Boero: Synopsis of the families and genera of the Hydromedusae of the world, with a list of the worldwide species , in: Thalassia Salentina, Vol. 24, 2000, pp. 65-66, PDF

Individual evidence

  1. ^ WoRMS - World Register of Marine Species - Turritopsis dohrnii (Weissmann, 1883). In: marinespecies.org. Retrieved July 29, 2015 .
  2. ^ A b M. P. Miglietta, S. Piraino, S. Kubota, P. Schucher: Species in the genus Turritopsis (Cnidaria, Hydrozoa): a molecular evaluation. 2006, in:  Journal of Zoological Systematics and Evolutionary Research 45 (1), pp. 11-19. doi : 10.1111 / j.1439-0469.2006.00379.x ( online )
  3. ↑ L. Martell, S. Piraino, C. Gravili, F. Boero: Life cycle, morphology and medusa ontogenesis of Turritopsis dohrnii (Cnidaria: Hydrozoa). In: Italian Journal of Zoology Vol. 83, Iss. 3, 2016 ( online )
  4. ↑ a b c Peter Schuchert: Revision of the European athecate hydroids and their medusae (Hydrozoa, Cnidaria): Families Oceanidae and Pachycordylidae. In: Rev. Suisse Zool. , Vol. 111 (2), 2004, pp. 315-369. PDF
  5. ↑ Giorgio Bavestrello, Christian Sommer & Michele Sarà: Bi-directional conversion in Turritopsis nutricula (Hydrozoa) , in: Bouillon, J. et al. (Ed.): Aspects of Hydrozoan Biology, Scientia Marina, Vol. 56 (2-3), 1992, pp. 137–140, PDF ( memento of the original from June 26, 2015 in the Internet Archive ) Info: The archive link became automatic used and not yet tested. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / evolucionuader.yolasite.com
  6. ↑ Stefano Piraino, Ferdinando Boero, Brigitte Aeschbach & Volker Schmid: Reversing the Life Cycle: Medusae Transforming into Polyps and Cell Transdifferentiation in Turritopsis nutricula (Cnidaria, Hydrozoa) , in: The Biological Bulletin, Vol. 190, 1996, p. 302– 312, PDF
  7. ↑ Shin Kubota: Distinction of Two Morphotypes of Turritopsis nutricula Medusae (Cnidaria, Hydrozoa, Anthomedusae) in Japan, with Reference to their Different Abilities to Revert to the Hydroid Stage and their Distinct Geographical Distributions. Biogeography, Vol. 7, 2005, pp. 41-50. PDF

Web links

Commons : Turritopsis dohrnii  - Collection of images, videos and audio files