Entoprocta

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Related to entoproct: Ectoprocta, Phoronida

Entoprocta

(ĕn'təprŏk`tə), animal phylum consisting of small marine organisms living in shallow coastal waters. The entoprocts are either colonial or solitary. The body is vase-shaped, with the upper edge covered by ciliated tentacles that direct microscopic animals and debris into the U-shaped digestive tract. A stalk with an enlarged base attaches the organism to seaweed, other marine organisms, shells, or other material. Of the 60 or more known species, only one is found in freshwater. While in some species the sexes are separate, other species are hermaphroditic. Eggs and larvae develop in the ovary, and larvae are free-swimming before growing stalks and attaching. Pedicellina is a common marine colonial entoproct.

Entoprocta

 

(or Kamptozoa), a phylum of invertebrate animals. Entoprocts are small, primarily colonial, animals (measuring from 1 mm to 1 cm) that lead a sessile way of life. The body consists of a calyx containing all the organs, which is attached by a flexible stalk to the substrate (in colonial forms, to the branching trunk of the colony—the stolon). The calyx is rimmed with a circlet of tentacles. The mouth and anus open on a recessed space (atrium) between the bases of the tentacles. There is no coelom. Most entoprocts are dioecious; some are hermaphroditic. In the recess between the tentacles, the female has a brood cavity, where the eggs are fertilized and develop to the stage of trochophore-like larva. Development is accompanied by metamorphosis. In addition to sexual reproduction, there is asexual reproduction by means of budding.

All entoprocts are marine, except for one freshwater species, Urnatella gracilis. Entoprocts feed on detritus and microscopic algae. They live in shallow waters, which are rich in algae, but some descend to a depth of up to 300 m. In the USSR, 16 species are found in the northern seas and two in the Black Sea and Sea of Azov, one of which has found its way into the Caspian Sea.

REFERENCES

Rukovodstvo po zoologii, vol. 1. Edited by L. A. Zenkevich. Moscow-Leningrad, 1937.
Zhizn’zhivotnykh, vol. 1. Moscow, 1968. G. A. Kliuge

Entoprocta

[‚ent·ə′präk·tə]
(invertebrate zoology)
A group of bryozoans, sometimes considered to be a subphylum, having a pseudocoelomate visceral cavity and the anus opening inside the circlet of tentacles.
References in periodicals archive ?
Results of the study, by an international research team, suggest that entoprocts appeared earlier than previously thought.
Entoprocts are small organisms that feed by straining food particles from water.
Some anatomical characteristics of Cotyledion tylodes are comparable to those of modern entoprocts, especially the presence of a U-shaped gut with a mouth and anus surrounded by a crown of tentacles.
Its body was covered in external, hardened structures called sclerites, which are not found on modern entoprocts.
Entoproct life-cycles and the entoproct/ectoproct relationship.
Although a monophyletic mollusc-entoproct clade is not commonly recognized in current molecular phylogenies, which may be due to the paucity of entoproct species for which adequate sequence data are available, some former morphology-based cladistic analyses have already recognized such an assemblage, classifying it as "Lacunifera" or "Sinusoida" (Bartolomaeus, 1993a,b; Haszprunar, 1996, 2000; Ax, 1999).
Comparing the nervous system anatomies of the entoproct creeping larva and basal molluscs, it becomes obvious that the former expresses a mosaic of larval and adult tetraneuralian characters.
As outlined above, the apical organs of most spiralians except for the polyplacophoran trochophore and the entoproct creeping larva are simple, with only about four serotonergic flask cells; this condition is thus regarded as basal for Spiralia.
In the suspension-feeding entoprocts, the direction of water flow is reversed (3).
Sessile polychaetes, lophophorates, pterobranchs, and entoprocts all have ciliated circumoral tentacles.