polyp

(redirected from Coral polyp)
Also found in: Dictionary, Thesaurus, Medical.

polyp,

in medicine, a benign tumor occurring in areas lined with mucous membrane such as the nose, gastrointestinal tract (especially the colon), and the uterus. Some polyps are pedunculated tumors, i.e., they grow on stems; others, attached by a broad base, are called sessile. Nasal polyps are usually associated with an allergic condition; since they interfere with breathing, it is advisable that they be removed. Uterine and gastrointestinal polyps are likely to cause bleeding, but, more important, they may undergo malignant degeneration and for this reason are also usually removed.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Polyp

 

a morbid growth that develops on mucosa of the respiratory tract, uterus, stomach, large intestine, rectum, and urinary bladder. Polyps are villous formations of various shapes; sometimes pear-shaped, they are usually broad-based or pedunculated. They may ulcerate and cause hemorrhages. Modern medical practice considers polyps precancerous, and therefore they are surgically removed.


Polyp

 

the common name for the predominantly benthic form of coelenterates. In metagenetic forms, that is, in hydrozoans (except hydras) and scyphozoans, polyps are capable only of vegetative reproduction, forming either medusae (in hydrozoans by budding, in scyphozoans by transverse division) or other polyps. Sexual reproduction is characteristic in such forms only in individuals of the medusa phase—free-swimming individuals or individuals remaining attached to the polyp. In homogenetic forms (hydrida and anthozoans), the polyps are capable of both sexual and vegetative reproduction. With sexual reproduction, larvae develop from the eggs and are transformed into polyps.

Polyps usually are cylindrical and measure from several millimeters to several centimeters tall (rarely up to 1 m). The upper part of the body contains the mouth, which is surrounded by tentacles. The base serves as a foot by which the polyp attaches itself to the substrate (in solitary forms) or to the colony (in colonial forms). There is often a hard external or internal skeleton of organic matter or limestone. The nervous system, which is developed considerably less than in the medusa, is in the form of a subepithelial nerve ganglion. Sex glands are present only in homogenetic forms and are located in the ectoderm (in Hydrida) or in the entoderm (in anthozoans). Sexual products are eliminated through ruptures in the walls of the gonads. In rare cases (in some actiniae), development occurs in the gastral cavity of the maternal body.

Polyps, except for hydras and a few related forms, are marine organisms. The majority lead a sedentary life; many form colonies. Movements are limited by the extension and contraction of the body and tentacles. Some solitary forms, hydras and actiniae, move slowly along the substrate; a few actiniae inhabit the depths. Polyps feed predominantly on animal substances, usually capturing their prey with their tentacles.

REFERENCES

See references under COELENTERATA.

D. V. NAUMOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

polyp

[′päl·əp]
(invertebrate zoology)
A sessile cnidarian individual having a hollow, somewhat cylindrical body, attached at one end, with a mouth surrounded by tentacles at the free end; may be solitary (hydra) or colonial (coral).
(medicine)
A smooth, rounded or oval mass projecting from a membrane-covered surface.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

polyp

1. Zoology one of the two forms of individual that occur in coelenterates. It usually has a hollow cylindrical body with a ring of tentacles around the mouth
2. Pathol a small vascularized growth arising from the surface of a mucous membrane, having a rounded base or a stalklike projection
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Researchers test the new technology by studying coral polyps - the millimeter-sized living creatures that make corals living organisms - in the Red Sea off the coast of Israel and off Maui, Hawaii.
Most coral polyps live in "colonies," which are groups of hundreds to thousands of genetically identical polyps formed when the original polyp grows copies of itself (the process is called budding).
A coral reef is built by very tiny, soft animals called coral polyps (cor-al pol-yps).
Bleaching is an event in which the zooxanthellae of the corals, which give corals their beautiful colors, are expelled from the coral polyps, leaving the colonies white.
Uniform fluorescence distribution occurs when fluorescent protein expression is distributed evenly across coral polyp cells (Fig.
On experimenting with various mixes the artificial reef blocks were created using a mix of dolomite (composed of calcium magnesium carbonate) and cement that coral polyps could latch on to thrive.
PHOTO| EVANS HABIL class="MsoNormalSome photographs show scenes of intriguing seabed ecosystems, vibrantly coloured microscopic sea creatures, and colonies of colourful coral polyps, all naturally cultivated over many years.
She compares the coral reef to a giant apartment building in New York City, with all the coral polyps living together in each apartment.
Mameng feeds on mollusks and the Crown-of-thorns starfish, which preys on coral polyps. Its secretions give sand on Apo beach its pink hue.
Their natural diet also is why they make risky reef aquarium candidates; they likely will consume coral polyps and clam mantles.