Marble crab

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Marble crab
Marble Crab (Procambarus fallax f. Virginalis), caught in the wild from southern Germany

Marble Crab ( Procambarus fallax f. Virginalis ), caught in the wild from southern Germany

Systematics
Partial order : Large crayfish (Astacidea)
Superfamily : Crayfish (Astacoidea)
Family : Cambaridae
Genre : Procambarus
Type : Procambarus fallax
Shape : Marble crab
Scientific name
Procambarus fallax f. virginalis
Martin et al., 2010

The marble crab ( Procambarus fallax f. Virginalis , also described as a separate species Procambarus virginalis since December 2017 ) is a form of the crayfish species Procambarus fallax . At first she was only known as an aquarium inhabitant in Germany, but her geographic origin and descent was unclear for a long time. Later morphological examinations and DNA analyzes showed that it is an asexual ( parthenogenetic ) form of the North American species Procambarus fallax from Florida and Georgia . The marbled carapace gives it its name .

The marble crab is now established as a neozoon in various countries around the world . Due to its high rate of reproduction, it is viewed as a potential threat to ancestral species populations.

features

The color and morphology of the marble crab arises from the general appearance of Procambarus fallax . Characteristic is the drawing of the carapace , which has a marbling on the side. The cancer grows up to 15 cm (usually 12 cm) long. He reaches a live weight of 15, exceptionally up to 30 g.

Multiplication and life cycle

The cancer is the only currently known crayfish to reproduce through parthenogenesis (virgin generation), males are unknown. This is the apomictic form of parthenogenesis, with meiosis completely failing during egg formation. Why and how this type of reproduction occurred in this (and only in this) crayfish species is still unclear. Some hypotheses, such as the origin of hybridization or infection by the Wolbachia bacterium , which are known to have caused parthenogenesis in other species, could be ruled out.

Maturing eggs develop from the ovaries , from which, depending on the water temperature and quality ( oxygen content ), around 120 young animals hatch after three to six weeks (record value: 724), and this in the aquarium every eight weeks all year round. After being laid on the pleopods , the eggs are attached to the underside of the abdomen (pleon) of the mother animals. During this time, the females do not eat any food and look for hiding places. The hatched young animals have a body length of about 4 mm. The first two youth stages do not eat any food and remain on the mother animal. After hatching, the young shed their skin regularly until, at around four months of age, after around 15 moults, they themselves reach sexual maturity. The normal generation time is around six months. A single female can produce eggs up to seven times, and in the adult stage it sheds its skin up to ten times. Its normal lifespan is around two years, the record is 1,610 days.

Although all young animals are genetically identical due to the way they reproduce, they differ noticeably in phenotype. For example, B. each of several hundred examined young animals on an individual drawing.

Oncologists at the German Cancer Research Center are trying to draw parallels between the unique clonal multiplication method of Marble crabs and that of tumor cells .

food

Cub
Young animals
Larva in the zoea stage; Length about 2 mm

The marble crab is an omnivore, with vegetable food predominating. In the aquarium hobby, flake food, oak and beech leaves are usually fed. No pronounced predatory behavior was observed, but sick and some bottom-living fish are found in aquariums, such as B. smaller catfish species (e.g. Otocinclus ) are captured. Dealing with the aquarium planting is described quite differently.

Systematics and origin

Marble crabs were discovered in German aquarium stores in the mid-1990s, the provenance of the animals can no longer be reconstructed. The original species Procambarus fallax occurs in North America. However, P. fallax reproduces separately and also shows a slightly different habitus .

As a breeding product , the marble crab is an anökozoon , i.e. a neozoon that arose under human influence.

Due to the ease of breeding and the fact that all offspring are genetically identical to the dam (i.e. clones ), the marble crab has now become a popular model organism in the laboratory.

The marble crab was added to the list of invasive alien species of Union concern for the European Union in 2016. Monitoring and control measures have been carried out in Germany since the beginning of 2018.

Ecological aspects

Today the marble crab is widespread in the aquarium hobby worldwide. In addition, it can also be found as a neozoon in many areas of the world , including in Central Europe . There are currently 15 detection sites in the wild in Europe, 13 of them after 2008. At least six of these are established, reproductive populations. Marble crabs are known from a wide variety of bodies of water, including flowing and standing, including garden ponds. They can also move overland for longer distances in damp weather, for example a specimen was found in a road underpass away from water. Because of their rapid reproduction, they are used as live bait when fishing for pike and pikeperch and are introduced into new waters by fishermen. The center of the introduction is Germany, where it occurs to the north as far as the Low German Plain; there are also individual finds from Italy , Slovakia and Austria .

A release of marble crabs into the wild or a "living dump" via the toilet has catastrophic effects from the point of view of the conservationist. In Madagascar , the drastic increase in introduced marble crabs is feared to have far-reaching consequences for native flora and fauna. In the meantime, a first occurrence was also known in Japan .

Epidemiology and Measures

Marble cancer is known as a vector of disease . This is another reason why attempts are being made to limit the spread of this species.

Cancer plague

The marble crab is largely immune to the cancer plague itself . Since it can transmit the disease and rob ecological resources, it represents a potential threat to indigenous cancers such as the noble crayfish ( Astacus astacus ) or the Galician crayfish ( Astacus leptodactylus ).

Chytridiomycosis

Researchers and environmental authorities see the possibility that chytrid fungi are spread by the marble crab. This fungus is endangered by amphibians because chytridiomycosis contributes regionally to species extinction, as it is known for the disease of the fire salamander , for example . Batrachochytrium dendrobatitis does not survive dehydration. In order to prevent this fungus from spreading, material that comes into contact with water, such as water sports or fishing equipment, must be dried completely. The trade in animals and plants from affected waters, as well as their movement and subsequent contact with local fauna, also represent a major risk for B. dendrobatitis-free regions and their amphibians.

activities

In order to limit the spread of marble cancer and diseases, all member states within the EU were obliged to take appropriate measures and to record their success. The development of the population is monitored by biomonitoring . The following management measures for marble cancer are known: "M 1: public relations and education", "M 2: removal", "M 3: creation of buffer zones", "M 4: erection of cancer barriers or maintenance of existing barriers", "M 5: draining or backfilling and new construction of (still) waters ”,“ M 6: Targeted promotion of natural opponents ”.

literature

Web links

Individual evidence

  1. ↑ Peer Martin, Nathan J. Dorn, Tadashi Kawai, Craig van der Heiden, Gerhard Scholtz: The enigmatic Marmorkrebs (marbled crayfish) is the parthenogenetic form of Procambarus fallax (Hagen, 1870) . In: Contributions to Zoology . tape 79 , no. 3 , 2010, p. 108-118 ( PDF ). P. 114.
  2. ↑ Frank Lyko: The marbled crayfish (Decapoda: Cambaridae) represents an independent new species. Zootaxa, 4363, 4, pp. 544–552, December 2017 doi : 10.11646 / zootaxa.4363.4.6
  3. ↑ Peer Martin, Nathan J. Dorn, Tadashi Kawai, Craig van der Heiden, Gerhard Scholtz: The enigmatic Marmorkrebs (marbled crayfish) is the parthenogenetic form of Procambarus fallax (Hagen, 1870) . In: Contributions to Zoology . tape 79 , no. 3 , 2010, p. 108-118 ( PDF ). Pp. 110-114.
  4. ↑ a b Christoph Chucholl, Michael Pfeiffer: First evidence for an established Marmorkrebs (Decapoda, Astacida, Cambaridae) population in Southwestern Germany, in syntopic occurrence with Orconectes limosus (Rafinesque, 1817) . In: Aquatic Invasions . tape 5 , no. 4 , 2010, p. 405-412 , doi : 10.3391 / ai.2010.5.4.10 ( PDF ).
  5. ↑ a b Marble Crab by A. Heeger on www.wirbellose.de, website of the AGW Working Group on Invertebrates of Inland Waters, last changed on June 21, 2017
  6. ^ Günter Vogt: Suitability of the clonal marbled crayfish for biogerontological research: a review and perspective, with remarks on some further crustaceans . In: Biogerontology . tape 11 , no. 6 , June 27, 2010, p. 643-669 , doi : 10.1007 / s10522-010-9291-6 .
  7. ^ G. Vogt: The marbled crayfish: a new model organism for research on development, epigenetics and evolutionary biology . In: Journal of Zoology . tape 276 , no. 1 , September 2008, p. 1–13 , doi : 10.1111 / j.1469-7998.2008.00473.x .
  8. ↑ Frank Lyko: The clone cancer from nature - a model for tumors. Retrieved July 24, 2019 .
  9. ↑ Chris Lukhaup (2001): Procambarus sp., The marble crab - a grateful aquarium inhabitant. Aquaristik aktuell 4/2001: 48–51.
  10. ↑ Kowarik, Ingo: Biologische Invasionen; Neophytes and Neozoa in Central Europe . 2nd Edition. Eugen Ulmer KG, Stuttgart 2010, ISBN 978-3-8001-5889-8 . P. 348. Kowarik refers to:
    Marten, M., Werth, C. & Marten, D. (2004): The marble crab (Cambaridae, Decapoda) in Germany - another neozoon in the Rhine catchment area. Lauterbornia 50: 17-23
  11. ↑ Günter Vogt (2011): Marmorkrebs: Natural crayfish clone as emerging model for various biological disciplines. In: Journal of Biosciences 36: 377-382. doi : 10.1007 / s12038-011-9070-9
  12. ↑ List of Invasive Alien Species of Union Concern (PDF) accessed on July 15, 2016
  13. ↑ a b c d e "Invasive Cancer Types" - Management and Action Sheet for Regulation (EU) No. 1143/2014, country editions:
  14. ↑ Spread of the marble crab ( Memento of the original from January 16, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (Online forum) @1@ 2Template: Webachiv / IABot / www.aquaristik-live.de
  15. ↑ Christoph Chucholl, Katharina Morawetz, Harald Groß: The clones are coming - strong increase in marble cancer [Procambarus fallax (Hagen, 1870) f. virginalis] records from Europe . In: Aquatic Invasions . tape 7 , no. 4 , 2012, p. 511-519 , doi : 10.3391 / ai.2012.7.4.008 ( PDF ).
  16. ↑ Marble crabs found in a pond for the first time. In: ORF . October 27, 2018, accessed October 27, 2018 .
  17. ↑ Gluttonous marble crabs threaten Madagascar . Die Welt, August 19, 2010
  18. ↑ Z. Faulkes, TP Feria, J. Muñoz: Do Marmorkrebs, Procambarus fallax f. virginalis, threaten freshwater Japanese ecosystems? In: Aquatic biosystems. Volume 8, number 1, June 2012, p. 13, doi : 10.1186 / 2046-9063-8-13 , PMID 22738196 , PMC 3460755 (free full text).
  19. ^ Tadashi Kawai (Ed.), Zen Faulkes (Ed.), Gerhard Scholtz (Ed.): Freshwater Crayfish: A Global Overview . CRC Press, 2015, ISBN 9781466586406 , p. 6
  20. ↑ a b Christoph Chucholl: Predicting the risk of introduction and establishment of an exotic aquarium animal in Europe: insights from one decade of Marmorkrebs (Crustacea, Astacida, Cambaridae) releases ( Memento of September 30, 2017 in the Internet Archive ), Management of Biological Invasions (2014) Volume 5, Issue 4: 309-318.
  21. ↑ Chucholl, C. & Blank, S. & Brinker, A. (2017): The protection of the crayfish - A guide . Ministry for Rural Areas and Consumer Protection Baden-Württemberg, Stuttgart, 84 pages