Gyrocotylidea
| Gyrocotylidea | ||||||||||
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Gyrocotyle rugosa |
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Gyrocotylidea | ||||||||||
| Poche , 1926 |
The Gyrocotylidea are an order within the Monozoic tapeworms . Like all tapeworms , they live as endoparasites in other animals, specializing in the sea cats (Holocephalii) as final hosts and probably crustaceans as intermediate hosts. Unlike true tapeworms , they have no pseudo-segmentation in proglottids and only have a pair of sexual organs.
About ten species of this taxon are known to date .
features
The Gyrocotylidea reach body lengths of 2 to 20 cm. Anatomically, they are distinguished by the special structure of its attachment of the host serving rosette organ from. This is formed at the rear end of the animals and consists of flap-like appendages with which the animals attach themselves to the spiral intestine of their hosts. The front end has a distinct depression that is completely lined with the neodermis , the sides of the body consist of lobed hems.
Unlike the real tapeworms , these monozoic tapeworms only have a set of genital organs , so they have no pseudo-segmentation in proglottids .
Like all tapeworms, the gyrocotylidea also belong to the neodermata and accordingly have a neodermis, a "secondary body covering" that consists of cells of mesodermal origin and replaces the original epidermis. As with all tapeworms, this is covered with microvilli , which differ from those of real tapeworms in their shape and, above all, in the lack of an electron-dense tip. In addition, the microvilli border differs in the different body sections and the neodermis is equipped with spines of unknown function.
The central nervous system of the Gyrocotylidea consists of a brain and a larger ganglion that innervates the rosette organ, as well as two main nerves. There are numerous sensory cells, especially at the anterior end and in the rosette organ. For excretion , the animals have protonephridia , which differ from those of the real tapeworms and the amphilinidea in that they have so-called nonterminal flames in the nephridial canal. The excretion itself occurs through paired Nephropori in the front half of the body.
Reproduction
The Gyrocotylidea are hermaphrodites and accordingly have both male and female sexual organs. The testes are located as testicular follicles in the anterior part of the body, while the vittel follicles are located on the sides of the body. From here the yolk cells (vitellocytes) are transported to the ootype via ciliate ducts, the Vitelloducts . This is also where the eggs formed and fertilized in the germarium come , which are assembled and then stored in thousands in the uterus in the front half of the body and released into the host's intestine.
The eggs reach the open water via the manure's droppings, where a free-floating Lycophora larva hatches. This is about 100 μm long and has ten pairs of uniform hooks, 4 glands and well-developed photoreceptors .
Way of life
The exact way of life of the animals is unknown. The adult worms live in the intestines of sea cats , their larvae probably in various crustaceans .
supporting documents
- ↑ a b c d e f g h Willi Xylander : Neodermata. In: W. Westheide, R. Rieger (Ed.): Special Zoology. Part 1: Protozoa and invertebrates. Gustav Fischer Verlag, Stuttgart / Jena 1996, ISBN 3-437-20515-3 , p. 249.
literature
- Willi Xylander : Neodermata. In: W. Westheide, R. Rieger (Ed.): Special Zoology. Part 1: Protozoa and invertebrates. Gustav Fischer Verlag, Stuttgart / Jena 1996, ISBN 3-437-20515-3 , p. 249.