Dugesia
| Dugesia | ||||||||||||
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Dugesia subtentaculata |
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| Scientific name | ||||||||||||
| Dugesia | ||||||||||||
| Girard , 1850 |
Dugesia is a genus of the vortex worms (colloquially often calledplanariansafter the old genus Planaria ). The vortex worms belong to the flatworms . The representatives of the genus Dugesia reach a size of a maximum of about 2.5 cm. The species Dugesia gonocephala ( European creek planaria ) is a frequent inhabitant of Central European inland waters. Dugesia species feed on carnivore .
Appearance
Dugesians are very flattened worms, a few millimeters to more than two centimeters long, depending on the species, the head of which looks like an isosceles triangle. Sitting on top of the head, sunk into cup-shaped depressions, simple eyes that enable the animal to recognize the direction of the incidence of light. The head does not have a mouth opening because the pharynx is anteriorly located approximately in the middle of the body. With strong lighting, the throat can also be seen from above in a binocular or microscope, but also with a strong magnifying glass.
behavior
The locomotion of the Dugesians is a kind of floating crawling: flagellated ciliated cells on the abdomen enable locomotion on a film of mucus which the animals secrete. They orient themselves in the light with their backs to the light, but generally show a preference for shade or darkness, which is why they often go unnoticed for a long time as aquarium inhabitants.
Reproduction
Dugesia species are hermaphroditic , so they have both male and female gonads. Many species can reproduce not only sexually, but asexually by simply dividing in half.
Regenerative ability
A specialty in the animal kingdom is the high regenerative capacity of the species. The animals have a high number of so-called neoblasts . In the event of injuries through division and specialization into individual cell types, these stem cells can very quickly close the wound and then regenerate all of the animal's missing tissues. So much so that every part of a dismembered into several parts Dugesia regenerates a complete animal within two to three weeks.
species
Some types:
- Dugesia agilis
- Dugesia antillana
- Dugesia dorotocephala
- Dugesia gonocephala (creek planaria)
- Dugesia japonica (Japanese planaria)
- Dugesia tigrina (spotted vortex worm)
Dugesia and man
For a long time, zoologists have known Dugesia's ability to regenerate. What has long been considered a curiosity is now an occasion to examine the physiology and genetics of the species in detail, because it is hoped that there will be indications of regeneration and therapy options for injured people.
Dugesia is also a well-known, albeit mostly undesirable, guest in the aquarium hobby. Only a few aquarium fish eat the animals. These include labyrinth fish , e.g. B. the paradise fish, one of the traditionally bred aquarium fish. The spotted strudelworm ( Dugesia tigrina , synonym Girardia tigrina ) may have been introduced into European waters through aquaristics. Today it is considered a neozoon in all of Central Europe .
Web links
- Pictures of Dugesia gonocephala at Biopix
- YouTube video (English): Want a Whole New Body? Ask This Flatworm How
- Volker Stollorz : Faith Healer - The Secret of Dr. Flatworm
- Animal Diversity Web: Dugesia
literature
- EJ de Vries: The biogeography of the genus Dugesia (Turbellaria, Tricladida, Paludicola) in the Mediterranean region. Journal of Biogeography, 12, pp. 509-518, 1985.
- R. Sluys, M. Kawakatsu, M. Riutort, J. Baguña: A new higher classification of planarian flatworms (Platyhelminthes, Tricladida). Journal of Natural History, 43, pp. 1763-1777, 2009.
Individual evidence
- ↑ Profile of the spotted strudelworm, Dugesia tigrina. Neobiota: New species in diving waters
- ^ Dugesia tigrina Aquatic neozoa in Lake Constance.