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whorl

 
Dictionary: whorl   (hwôrl, wôrl, hwûrl, wûrl) pronunciation
whorl
(Click to enlarge)
whorl

whorled leaves
(Elizabeth Morales)
n.
  1. A form that coils or spirals; a curl or swirl: spread the icing in peaks and whorls.
  2. Botany. An arrangement of three or more leaves, petals, or other organs radiating from a single node.
  3. Zoology. A single turn or volution of a spiral shell.
  4. One of the circular ridges or convolutions of a fingerprint.
  5. Architecture. An ornamental device, as in stonework or weaving, consisting of stylized vine leaves and tendrils.
  6. A small flywheel that regulates the speed of a spinning wheel.

[Middle English whorle, alteration of whirle, whirl, from whirlen, to whirl. See whirl.]


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A spiral arrangement, as in the hairs that go to make up a cowlick.


A group of three or more leaves or shoots that emerge from a single node.

Wikipedia: Whorl (mollusc)
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View of the spire side of the planispiral shell of the freshwater snail Anisus septemgyratus. This shell has seven and a half whorls
A fossil shell of the marine gastropod Turritella communis. This shell has nine whorls

A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the ammonites.

A spiral shell can be visualized as consisting of a long conical tube, the growth of which is coiled into an overall helical or planispiral shape, for reasons of both strength and compactness.

The number of whorls which exist in an adult shell of a particular species depends on mathematical factors in the geometric growth, as described in work of D’Arcy Wentworth Thompson (On Growth and Form) and David Raup. The main factor is how rapidly the conical tube expands (or flares-out) over time. When the rate of expansion is low, such that each subsequent whorl is not that much wider than the previous one, then the adult shell has numerous whorls. When the mathematical factors governing the pattern of growth are such that there is a very rapid expansion of the conical shape, of the shell tube, then the adult shell has very few whorls.

The number of whorls present in an adult shell differs greatly in various taxa. The extant marine gastropod families Turritellidae and Terebridae, and the extinct Mesozoic family Nerineidae, have very high spired shells with a large number of whorls, and a relatively small aperture.

The shells of a few genera of gastropods, and of the cephalopod genus Spirula, have whorls that are disconnected.


Contents

Terminology

  • Apical whorls—the whorls near the apex or tip of the shell of gastropods
  • Body whorl—The most recently formed whorl of a spiral shell, in which most of the body of the animal is found
  • Nuclear whorl(s)—small, generally smooth whorls formed within the egg, and constituting the apex of the shell
  • Protoconch—a larval shell of a mollusc; also refers to protoconch whorls of an adult shell
  • Teleoconch—all the whorls of a shell after the protoconch whorls

References

Further reading

External links


Translations: Whorl
Top

Dansk (Danish)
n. - vinding, krans
v. intr. - danne vindinger

Nederlands (Dutch)
spiraal (vormig), lijn van een vingerafdruk

Français (French)
n. - spirale, volute, spire, verticille (de pétales)
v. intr. - former une spirale, se déplacer en volutes

Deutsch (German)
n. - Wirtel, Windung, Wirbel
v. - sich ringeln

Ελληνική (Greek)
n. - δακτύλιος, έλικας, σπείρα

Italiano (Italian)
spira, giro di spirale, spirale di impronta digitale

Português (Portuguese)
n. - verticilo (m) (Bot.), qualquer coisa que gira

Русский (Russian)
завитушка, виток (спирали), завиток (раковины), изгиб (стебля)

Español (Spanish)
n. - espiral, espira, verticilo
v. intr. - moverse en forma circular o en espirales

Svenska (Swedish)
n. - krans, vindling

中文(简体)(Chinese (Simplified))
轮生体, 螺旋环, 螺纹, 盘旋, 打转

中文(繁體)(Chinese (Traditional))
n. - 輪生體, 螺旋環, 螺紋
v. intr. - 盤旋, 打轉

한국어 (Korean)
n. - 나선형의 물체, 와상형의 지문, (귀의) 달팽이관의 소용돌이
v. intr. - 나선형이 되다

日本語 (Japanese)
n. - 輪生, 螺旋, 渦巻き

العربيه (Arabic)
‏(الاسم) فلكه المغزل, الكوكب, السوار, كل شي ملتف حلزوني, الثنيه أي إحدى ثنيات الصدفه الحلزونيه‏

עברית (Hebrew)
n. - ‮דור עלים, קו סלילי (בקונכיה), קו מעגלי בטביעת אצבעות‬
v. intr. - ‮נע בקו סלילי, נע בעקלתון או בפיתולים‬


 
 

 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Gardener's Dictionary. Taylor's Dictionary for Gardeners, by Frances Tenenbaum. Copyright © 1997 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Whorl (mollusc)" Read more
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