Entoprocta (Gr. entos inside + proktos anus) is a phylum of small aquatic animals, ranging in size from 0.5 mm to 5.0 mm. They have a lophophore, and as their name suggests, are distinguished from other lophophorates by the position of the anus inside the ring of cilia rather than outside. Other names include goblet worm and kamptozoan.
Entoprocts are filter feeders, their tentacles secreting a mucus that catches food particles, which is then moved towards the mouth by cilia on the tentacles. Nearly all species are sedentary, attached to the substrate by a stalk, with the body being cup-shaped. Some species are colonial, with multiple animals on branching systems of stalks.
Entoprocts can reproduce either by budding, or sexually. They are unusual in being sequential hermaphrodites.
The phylum includes about 150 species in several families. While most species are marine, the freshwater species Urnatella gracilis is widespread.
Hatschek (1888) treated the Entoprocta as a division of his group Scolecida, characterized by the possession of a primary body-cavity and of protonephridia; while he placed the Ectoprocta, with the Phoronida and Brachiopoda, in a distinct group, the Tentaculata.
In the Entoprocta the tentacles are withdrawn by being infolded into the "vestibule," a depression of the oral surface which can be closed by a sphincter muscle.
The development of the Ectoprocta is intelligible on the hypothesis that the Entoprocta form the starting-point of the series.
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