Phyllopharyngea
Encyclopedia
The Phyllopharyngea are a class of ciliate
protozoa, including some which are extremely specialized. Motile cells typically have cilia restricted to the ventral surface, or some part thereof, arising from monokinetids with a characteristic ultrastructure. In both chonotrich
s and suctoria
, however, only newly formed cells are motile and the sessile adults have undergone considerable modifications of form and appearance. Chonotrichs, found mainly on crustacean
s, are vase-shaped, with cilia restricted to a funnel leading down into the mouth. Mature suctorians lack cilia altogether, and initially were not classified as ciliates.
The mouths of Phyllopharyngea are characteristically surrounded by microtubular ribbons, called phyllae. Nematodesmata, rods found in several other classes of ciliates, occur among the subclass Phyllopharyngia, most of which are free-living. In others, the mouth is often modified to form an extensible tentacle, with toxic extrusome
s at the tip. These are especially characteristic of the suctoria, which feed upon other ciliates, and are unique among them in having multiple mouths on each cell. They are also found in many rhynchodids, which are mostly parasites of bivalves.
Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella...
protozoa, including some which are extremely specialized. Motile cells typically have cilia restricted to the ventral surface, or some part thereof, arising from monokinetids with a characteristic ultrastructure. In both chonotrich
Chonotrich
Chonotrichia is a subclass of phyllopharyngeid ciliates. These single-celled organisms are sessile at maturity and usually live on crustaceans as ectosymbionts....
s and suctoria
Suctoria
Suctoria are sessile ciliates which feed by extracellular digestion and lack cilia in the adult phase. They were originally thought to feed by suction – hence their name. In fact, they use specialized microtubules to ensnare and manipulate their prey...
, however, only newly formed cells are motile and the sessile adults have undergone considerable modifications of form and appearance. Chonotrichs, found mainly on crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, are vase-shaped, with cilia restricted to a funnel leading down into the mouth. Mature suctorians lack cilia altogether, and initially were not classified as ciliates.
The mouths of Phyllopharyngea are characteristically surrounded by microtubular ribbons, called phyllae. Nematodesmata, rods found in several other classes of ciliates, occur among the subclass Phyllopharyngia, most of which are free-living. In others, the mouth is often modified to form an extensible tentacle, with toxic extrusome
Extrusome
Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions....
s at the tip. These are especially characteristic of the suctoria, which feed upon other ciliates, and are unique among them in having multiple mouths on each cell. They are also found in many rhynchodids, which are mostly parasites of bivalves.