Gill gut

Sea squirts larva with branchial gut (3)

In the adult sea squirt, Clavelina lepadiformis , the gill gut is clearly visible.

The gill intestine ( tractus respiratorius ) is an organ that is found in adult individuals in two of the three sub-tribes of the chordates (chordata), the aquatic tunicates and skullless , but it is a commonly derived feature ( synapomorphy ) of all chordata. The gill intestine is a part of the foregut in which there is a breakthrough of gill slits ( up to 1000 breakthroughs in sea squirts ), which serve to separate particles from the water.

The “primitive” chordates are able to filter their food through the gill slits by sucking in / swirling water through the mouth opening. The smallest food particles stick to the gill slits, which are often lined with eyelashes, and are then fed to the adjacent, digestive part of the intestine. This takes place via a mucus that is secreted by the hypobranchial groove (also called the endostyle ) located at the base of the gill intestine . The hypobranchial trough is homologous to the thyroid gland of vertebrates and its cells can already accumulate the iodine in seawater and incorporate it into pseudodistomines ( homologous to thyroxine molecules ).

The gill bowel appears in the embryonic development of all vertebrates, including humans, but in many chordates it is subject to a later reconstruction and change of function.

Individual evidence

↑ Lexicon of Biology
^ Günther Sterba : On the phylogenesis of the gill intestine of the chordates. In: International review of the entire hydrobiology and hydrography . Volume 46, 1961, doi : 10.1002 / iroh.19610460111 , pp. 105-114.
↑ ^a ^b Bernhard Werner: About the mechanism of the acquisition of food of the tunicates, especially the ascidians . In: Helgoland Marine Research . Volume 5, 1954, pp. 57-92 ( PDF document ).
↑ Bernhard Werner: The principle of the endless slime filter when acquiring food for invertebrates marine animals. In: International review of the entire hydrobiology and hydrography . Volume 44, 1959, pp. 181-215 ( Link ).
↑ Stefan Ries: Attempts at the total synthesis of pseudodistomin C and E - A new synthetic route. Würzburg, 2009 ( PDF document ).
↑ Wilfried Westheide , Reinhard Rieger (ed.): The body of the Craniota and the differentiation of its basic shape . In: Special Zoology. Part 2: vertebrates or skulls . Spectrum Akademischer Verlag, Heidelberg / Berlin, 2010, ISBN 978-3-8274-2220-0 , pp. 3-14.

[1] Lexicon of Biology

[Sterba_105-114-2] Günther Sterba : On the phylogenesis of the gill intestine of the chordates. In: International review of the entire hydrobiology and hydrography . Volume 46, 1961, doi : 10.1002 / iroh.19610460111 , pp. 105-114.

[Werner_1954_57-92-3] Bernhard Werner: About the mechanism of the acquisition of food of the tunicates, especially the ascidians . In: Helgoland Marine Research . Volume 5, 1954, pp. 57-92 ( PDF document ).

[Werner_1959_181–215-4] Bernhard Werner: The principle of the endless slime filter when acquiring food for invertebrates marine animals. In: International review of the entire hydrobiology and hydrography . Volume 44, 1959, pp. 181-215 ( Link ).

[Ries_2009-5] Stefan Ries: Attempts at the total synthesis of pseudodistomin C and E - A new synthetic route. Würzburg, 2009 ( PDF document ).

[Rieger_2010_3–14-6] Wilfried Westheide , Reinhard Rieger (ed.): The body of the Craniota and the differentiation of its basic shape . In: Special Zoology. Part 2: vertebrates or skulls . Spectrum Akademischer Verlag, Heidelberg / Berlin, 2010, ISBN 978-3-8274-2220-0 , pp. 3-14.