The siphonoglyph is a

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

ted groove at one or both ends of the mouth of sea anemones and some

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secre ...

s. The siphonoglyph extends into a

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its ...

and is used to create currents of water into the pharynx. These water currents are important for respiration and maintenance of internal pressure. The presence of a siphonoglyph (or two siphonoglyphs) in several

anthozoan Anthozoa is a subphylum of marine invertebrates which includes the sea anemones, stony corals and soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plankton. The basic unit of t ...

s (including species from the orders Zoantharia, Ceriantharia,

Antipatharia Antipatharians, also known as black corals or thorn corals, are an order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of or ...

, and Octocorallia) introduces an element of bilateral symmetry into the particular species' body plan (Beklemishev 1969). Some have argued that the presence of bilateral symmetry in these anthozoans is evidence that the ancestor to bilaterians and cnidarians may have had a bilaterally symmetrical body plan (Finnerty 2003).

References

* * Anthozoa Cnidarian anatomy {{anthozoa-stub