Aplousobranchia
The colonial Green Riffseescheide ( Didemnum molle ). Green edged, the common Egestionsöffnung ( outflow ) of all individual animals. When you expand (by clicking the image) visible, the small single ingestion openings ( inflow ) of the individual animals.
The Aplousobranchia (Size: not folded gills and intestine ) are sessile live tunicates ( Tunicata, Urochordata ) and are used in traditional systematics therefore to the class of " sea squirts " ( Ascidiacea ) were counted. They live in the sea, especially in shallow water. However, there are also known types of greater depths.
Features
The types of group form by budding animal poles of many individual copies, which is considered a primitive character ( Plesiomorphie ). Your gills and intestine is not differentiated and easily built. The larvae of Aplousobranchia built complex. They first develop as an embryo in the shell ( Tunica ), then as a swimming larva in the open water. The number of larvae is low, they are large and have a distinct yolk sac. Your free-floating phase is short. Then they settle on a solid substrate and perform the metamorphosis to adult sea squirt, the asexually propagated to form a bull Stock.
Outer systematics
The sea squirts do not form a monophyletic group by DNA sequence analysis. A cladogram shows the actual relationship of tunicates. The Aplousobranchia are the sister group of the pelagic Appendikularien:
Stolidobranchia ( " sea squirts " )
Phlebobranchia ( " sea squirts " )
Salps ( Thaliacea )
Aplousobranchia ( " sea squirts " )
Appendikularien ( Larvacea )
Families
- Cionidae
- Clavelinidae Forbes & Hanley, 1848
- Diazonidae
- Didemnidae Giard, 1872
- Euherdmaniidae
- Holozoidae
- Placentelidae
- Polycitoridae Michaelsen, 1904
- Polyclinidae Milne -Edwards, 1841
- Protopolyclinidae
- Pseudodistomidae
- Pycnoclavellidae
- Ritterellidae
- Stomozoidae