Aplousobranchia

Aplousobranchia
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.
Systematics
Over trunk : Neumünder (Deuterostomia) Trunk : Chordates (chordata) Sub-stem : Tunicates (urochordata) Class : Sea squirts (Ascidiae) Order : Enterogona Subordination : Aplousobranchia
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.

Clavelina robusta (black-white) & Clavelina flava (orange)

Mushroom Sea Squirt ( Nephtheis fascicularis )

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	Stolidobranchia  ("sea squirts")      Phlebobranchia  ("sea squirts")      Salps  (Thaliacea)      Aplousobranchia  ("sea squirts")      Appendicularia  (Larvacea)

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

Commons : Aplousobranchia  - collection of images, videos and audio files

• Gittenberger, A., Monniot, C. (2010). Aplousobranchia . In: World Ciliophora Database. World Register of Marine Species Aplousobranchia