Barrel Alps
| Barrel Alps | ||||||||||||
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Barrel Alps ( Doliolidae ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Doliolidae | ||||||||||||
| Bronn , 1862 |
The barrel alps (Doliolidae) - also called Cyclomyaria - are free-swimming tunicates . There are four genera with around 15 species.
The elastic, transparent coat is surrounded by 8 to 9 muscle ligaments, which act antagonistic to the coat. The animals have a complicated generation change : through sexual reproduction an oozoid (foster animal) is created, while vegetative means several stages (blastozoids).
The oozoid produces proliferous buds in an asexual way from a so-called stolo located on the ventral side, which are transferred via their own carrier cells (phorocytes) to the dorsal stolo (process at the dorsal end). The blastozoids formed by buds are arranged in three rows on the dorsal stolo. The blastozoids that are on the sides have a large gill intestine , they feed the colony and are called trophozoids.
The foster animal takes on the function of transporting the colony. The animals on the median row (phorozoids) take on a care function and develop a sex bud that divides 10 to 20 times. This results in the third generation, which consists of sex animals (gonozoids). The gonozoid is hermaphroditic and forms an egg inside, which is fertilized by foreign sperm cells . A larva with a chorda dorsalis arises from this egg . After a metamorphosis, it becomes a foster animal.
literature
- K. Deckert, Gisela Deckert , GE Freytag, G. Peters, G. Sterba: Urania animal kingdom, fish, amphibians, reptiles. Urania-Verlag, 1991, ISBN 3-332-00376-3 .
