Aplousobranchia
Aplousobranchia | ||||||||||||
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The colonial Green Reef Sea Squirt ( Didemnum molle ). Outlined in green, the common egestion opening (outflow opening) of all individual animals. When enlarged (by clicking on the picture) you can see the small individual ingestion openings (inflow openings) of the individual animals. |
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Systematics | ||||||||||||
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Scientific name | ||||||||||||
Aplousobranchia | ||||||||||||
Lahille , 1887 |
The Aplousobranchia ( size : unfolded gill intestine) are sessile-living tunicates (Tunicata, Urochordata) and are therefore counted in the traditional system to the class of " sea squirts " (Ascidiacea). They live in the sea, especially in shallow water. However, species from greater depths are also known.
features
The species of the group form animal hives from many individual specimens by budding , which is considered an original feature ( plesiomorphism ). Your gill gut is undifferentiated and simply built. The larvae of the Aplousobranchia are complex. They develop first as an embryo in a coat (tunica), then as a swimming larva in the open water. The number of larvae is small, they are large and have a distinct yolk sac. Your free-swimming phase is short. Then they settle on a solid substrate and undergo metamorphosis into a fully grown sea squirt, which reproduces asexually to form an animal hive.
External system
According to DNA sequence analyzes, the sea squirts do not form a monophylum . A cladogram shows the actual relationship of the tunicates. The Aplousobranchia are the sister group of the pelagic appendicularia:
Tunicates |
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Familys
- Cionidae
- Clavelinidae Forbes & Hanley, 1848
- Diazonidae
- Didemnidae Giard, 1872
- Euherdmaniidae
- Holozoidae
- Placentelidae
- Polycitoridae Michaelsen, 1904
- Polyclinidae Milne-Edwards, 1841
- Protopolyclinidae
- Pseudodistomidae
- Pycnoclavellidae
- Ritterellidae
- Stomozoidae
literature
- Wilfried Westheide / Reinhard Rieger: special zoology part 1: unicellular and invertebrate animals , 2nd edition, spectrum Akademischer Verlag Heidelberg: Berlin, 2007, ISBN 3-8274-1575-6
- Svein A. Fossa / Alf Jacob Nilsen: Coral reef aquarium. Volume 6, Schmettkamp Verlag, 1998, ISBN 3-928819-18-6
Web links
- Gittenberger, A., Monniot, C. (2010). Aplousobranchia . In: World Ciliophora Database. World Register of Marine Species Aplousobranchia