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of the shell when the soft parts of the animal are retracted. The shape of the operculum varies greatly from one family of gastropods to another. It is fairly often circular, or more or less oval in shape. In species where the operculum fits snugly, its outline corresponds exactly to the shape of the
734:
of North
America, as detailing in masks, panels and paddles. These objects are used to represent the teeth in masks, and are used as a decorative element in many of the objects which play an important part in the art and culture of Northwest Coast peoples, including dishes for food, bentwood boxes,
722:
species are also used. The operculum has two sides of differing appearance. Either side or both may be displayed as jewelry or ornament. The internal side is flat and white, with a spiral suture line, while the external side is hemispherical, glossy, and variously colored and patterned. In the case
515:
The most common kind of operculum is composed of a thin to rather thick corneous protein material, which is yellow to brownish in color and is usually somewhat translucent. This matter is supple when in its natural state but may become brittle when it is dried out. The operculum varies in shape,
551:
The different shapes of opercula can include ungulate (hooflike), claw-like, or ovate. The type and shape of the operculum is used to help identify and classify related groups (genera) of land operculates, and likewise some marine operculates.
451:
299:
In many species of marine shelled snails which live subtidally, the operculum is greatly reduced in size, and no longer serves to seal the shell entrance. In a large number of families it has been eliminated completely.
198:
species, then for many years after that they were considered to be a form of paired or single operculum-like structures belonging to ammonites. More recently the aptychus or paired aptychi have been hypothesized to be a
271:, with mostly distinct nuclei, and long divided processes enter between the muscular fibres. The operculum, a cuticular development of these cells, is composed, as may be seen in the corneous opercula of
179:, a temporary structure that can in some cases serve some of the same functions as an operculum. The epiphragm may be distinguished from the true operculum by its homogeneity and want of growth marks.
973:. This site also provides fairly extensive material on the growth, development, and physiology of the gastropod operculum as well as dozens of pictures of both the operculum and its host shell.
501:
type 1: flexiclaudent spiral (mostly multispiral) operculum; its shape does not coincide with the aperture but fits by flexing into the aperture; predominantly present in archaeogastropods.
469:
215:. This is very important in intertidal marine snails during low tide, and this also enables operculate freshwater and land snails to survive periods of drought and dry weather.
486:
410:
determined by the number of whorls in the shell, but by the curvature of the aperture, and the necessity that the operculum should revolve fast enough to fit it constantly.
521:
433:
504:
type 2: rigiclaudent spiral (usually paucispiral) operculum; its shape fitting the aperture; present in archaeogastropods, but predominating in
Caenogastropoda.
156:
Many families have opercula that are reduced in size, and which are not capable of closing the shell aperture. Opercula have sometimes been modified: in the
1013:
507:
type 3: rigiclaudent concentric operculum; its shape fitting the aperture; predominant in higher neotaenioglossans and exclusive in neogastropods.
547:
overlay. The calcareous surface in some genera has color or ornamentation of various kinds including, for example, pustules and incised grooves.
296:
size. In many species, when the animal is active and crawling, part of the underside of the shell rests on the outer surface of the operculum.
144:
The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the
807:
Checa, Antonio G.; Jiménez-Jiménez, Antonio P. (1998). "Constructional
Morphology, Origin, and Evolution of the Gastropod Operculum".
1362:
307:, the operculum is elongated and sickle-shaped, and is used to dig into the sand to enable the conch to perform a leaping type of
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1282:
1006:
654:
shell/armour fragrance) respectively. Incense producers in these countries use the operculum of many conches and other marine
1307:
1297:
897:
674:
smell. The clean opercula are then ground to a powder and used as a scent fixative, in a technique similar to that used in
1372:
1337:
658:, including those found in Southeast Asia, South America, and East Africa. The opercula are traditionally treated with
520:
1403:
970:
709:" in rings, bracelets, amulets etc. These opercula are commonly known as "cats eye" (or more recently "Shiva's eye").
1454:
1439:
999:
218:
In those marine species where the operculum completely seals the shell, it can also serve as a protection against
1449:
1444:
477:
289:, of very thin superimposed layers. The cylindrical cells are attached with their head to the lowermost layer.
211:
Perhaps the most essential function of the operculum in gastropods is to allow snails to resist drying out, or
749:, chains and girdles composed of the coloured opercula of certain shells were considered valuable ornaments.
787:
423:
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spiral: when it grows only on one edge, and revolves as it grows; it is always sinistral in dextral shells.
314:
261:
muscle with an opercular disc dorsally to the upper surface of the posterior part of the foot. However, in
1302:
809:
526:
253:
showing how the back of the shell rests on the round operculum on top of the foot as the snail moves along
791:
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853:
441:
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Various forms of opercula in Pyrula; Purpura; Littorina; Aulopoma; Torinia; Neritopsis; Strombus; Conus
258:
48:
907:
818:
459:
292:
The operculum grows in size as the shell grows, such that the operculum remains in proportion to the
249:
160:
the operculum is claw-shaped and is used to push into the substrate in a leaping form of locomotion.
421:
radiated is a modification of the articulated operculum in which the spiral is not so evident as in
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Hard structure which closes the aperture of a gastropod when the animal retreats into the shell
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imbricated, or lamellar: when it grows only on one side, and the nucleus is marginal, as in
110:
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Zoologische
Anmerkungen zu zwei minoischen Siegelabdrücken mit einem Tritonshorn (Gattung
610:
268:
235:
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52:
822:
539:
The other kind of operculum is restricted to a few families of gastropods including the
406:
where they sometimes amount to twenty; the number of turns which the operculum makes is
1322:
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1287:
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snails are inoperculate, i.e. they do not have an operculum, with the exception of the
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190:(plural aptychi) existed. When these were first described they were thought to be
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depending on the family of snails and the shape of the aperture of their shells.
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There are two basic types of opercula in terms of their material composition:
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The oldest known human depiction of an operculum together with the shell of
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Example of a polygyrous spiral with eccentric nucleus in the operculum of
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claw-shaped, or unguiculate: with the nucleus apical or in front, as in
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121:, and in a minority of terrestrial gastropods, including the families
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multispiral or polygyrous: having many closely spaced spirals as in
991:
338:, and in other the nucleus is near the parietal margin of the shell.
685:
When burnt on its own, high quality operculum reportedly smells of
186:(extinct shelled cephalopods), a calcareous structure known as the
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is the species whose operculum is most renowned, although other
690:
671:
995:
727:
there is a prominent dark 'eye' and sometimes a greenish area.
492:
Fossil spiral opercula (both sides) from the
Pliocene of Cyprus
595:
200:
153:
of the shell and it serves to seal the entrance of the shell.
497:
In 1998 Checa and
Jimeneze proposed three types of opercula:
693:, while that of lower quality is reminiscent of burnt hair.
543:. This operculum structure has a corneous base with a heavy
322:
The structure of the operculum can be described as follows:
952:
Animal: The
Definitive Visual Guide to the World's Wildlife
247:
A photo of an individual of the freshwater snail species
257:
In life, the operculum is attached at the ending of the
326:
concentric: the nucleus is central or subcentral as in
239:
near Goat Island, New
Zealand, with a damaged operculum
117:; the structure is found in some marine and freshwater
630:
Operculum powder is also an important ingredient in
1381:
1275:
1199:
1163:
1030:
383:paucispiral or oligogyrous: with few spirals as in
705:is sometimes used as a very inexpensive organic "
175:pulmonate species are capable of secreting an
1007:
413:articulated, when it has a projection, as in
8:
105:that exists in many (but not all) groups of
796:. Philadelphia, The author. pp. 47–48.
623:incense material which is described in the
615:are most commonly used in regions near the
1014:
1000:
992:
619:. Opercula from these conches may be the
602:cultures. The operculum of conch species
782:
780:
776:
429:
971:Pictures of diverse gastropod opercula
878:
868:
7:
793:Structural and systematic conchology
701:The operculum of certain species of
638:incense making. Here it is called "
475:Example of an oligogyrous spiral in
439:Example of a concentric operculum (
372:; it is claw-shaped and serrated in
82:
697:As a gemstone or decorative object
222:when the snail body is retracted.
25:
1363:Reproductive system of gastropods
527:Tropidophora fimbriata haemostoma
392:subspiral or scarcely spiral, in
1368:Respiratory system of gastropods
1283:Circulatory system of gastropods
586:, especially varieties from the
524:An individual of the land snail
485:
468:
450:
432:
61:with corneous operculum in place
1308:Excretory system of gastropods
1298:Digestive system of gastropods
113:, and also in a few groups of
1:
1373:Sensory organs of gastropods
1338:Nervous system of gastropods
267:a layer of long cylindrical
101:anatomical structure like a
1404:Circumesophageal nerve ring
730:Opercula are often used in
1471:
976:Photo of opercula of some
745:reported in 1896 that, in
831:10.1017/S0094837300020005
646:sea shell fragrance) or "
590:, have long served as an
478:Cremnoconchus syhadrensis
81: 'cover, covering';
757:The largest opercula of
203:apparatus of ammonites.
55:of the freshwater snail
670:in order to remove any
899:The History of Mankind
743:The History of Mankind
598:tradition, as well as
535:
319:
254:
240:
75:
62:
45:
34:Shell of marine snail
523:
442:Filopaludina martensi
317:
246:
233:
51:
33:
594:material in ancient
582:Opercula of certain
460:Marstonia comalensis
250:Bithynia tentaculata
1328:Hypobranchial gland
1276:Internal soft parts
1200:External soft parts
957:DK Adult Publishing
931:. manandmollusc.net
852:Schifko G. (2005).
823:1998Pbio...24..109C
732:Northwest Coast art
678:with certain plant
578:As incense material
572:Minoan civilization
463:, scale bar: 200 μm
58:Viviparus contectus
949:Burnie, D (2001).
763:have been used as
605:Strombus tricornis
536:
320:
255:
241:
63:
46:
44:operculum in place
1455:Organic gemstones
1440:Gastropod anatomy
1427:
1426:
1353:Oesophageal pouch
1212:Caudal mucous pit
896:Ratzel F (1896).
865:. pp. 27–33.
712:The turban snail
650:" (Japanese: 甲香,
563:Charonia tritonis
111:freshwater snails
16:(Redirected from
1462:
1450:Mollusc products
1445:Incense material
1343:Nidamental gland
1267:Suprapedal gland
1164:Other hard parts
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760:Turbo marmoratus
739:Friedrich Ratzel
715:Turbo petholatus
689:or other animal
642:" (Chinese: 貝香;
489:
472:
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269:epithelial cells
171:. However, some
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37:Lunella torquata
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965:External links
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817:(1): 109–132.
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625:Book of Exodus
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959:. p. 24.
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933:. Retrieved
929:"Operculata"
923:
913:November 28,
911:. Retrieved
898:
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810:Paleobiology
808:
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765:paperweights
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181:
162:
155:
143:
90:
86:
74:
66:
64:
56:
35:
1409:Trochophore
1394:Pseudofeces
1348:Odontophore
1303:Diverticula
1247:Pneumostome
1090:Planispiral
985:Busycotypus
879:|work=
859:) als Motiv
788:Tryon G. W.
617:Middle East
213:desiccation
173:terrestrial
135:Maizaniidae
123:Helicinidae
115:land snails
1434:Categories
1358:Osphradium
1333:Nephridium
1252:Rhinophore
1242:Parapodium
1171:Clausilium
1110:Selenizone
1100:Protoconch
1050:Body whorl
771:References
703:Turbinidae
584:gastropods
556:Human uses
545:calcareous
541:Turbinidae
532:calcareous
363:Turbinella
335:Ampullaria
309:locomotion
259:columellar
158:Strombidae
139:Pomatiidae
131:Aciculidae
119:gastropods
107:sea snails
99:calcareous
91:operculums
69:(from
42:calcareous
18:Operculate
1389:Epiphragm
1293:Ctenidium
1181:Operculum
1176:Love dart
1140:Umbilicus
1105:Sculpture
1085:Peristome
1060:Columella
1023:Gastropod
908:MacMillan
881:ignored (
871:cite book
687:castoreum
640:bèi xiāng
534:operculum
424:Navicella
386:Littorina
354:Paludomus
348:Xenophora
294:apertural
220:predators
207:Functions
184:ammonites
177:epiphragm
165:pulmonate
77:operculum
67:operculum
40:with the
1222:Cnidosac
1040:Aperture
857:Charonia
839:88680117
790:(1882).
707:gemstone
676:perfumes
636:Japanese
375:Strombus
264:Buccinum
188:aptychus
151:aperture
146:aperture
103:trapdoor
95:corneous
87:opercula
1419:Veliger
1399:Torsion
1025:anatomy
988:species
979:Busycon
819:Bibcode
747:Oceania
664:alcohol
660:vinegar
648:kai kou
632:Chinese
600:Arabian
592:incense
588:Red Sea
403:Trochus
343:Purpura
280:Purpura
226:Anatomy
196:bivalve
141:, etc.
93:) is a
1262:Siphon
1232:Mentum
1227:Mantle
1217:Cerata
1191:Radula
1135:Suture
1055:Callus
935:9 July
904:London
837:
680:resins
656:snails
621:onycha
596:Jewish
416:Nerita
395:Thiara
351:, and
305:conchs
286:Triton
192:valves
85:
1382:Other
1237:Notum
1186:Pearl
1155:Whorl
1150:Varix
1145:Valve
1125:Spire
1095:Plait
1075:Nacre
1032:Shell
863:(PDF)
835:S2CID
720:Turbo
691:musks
672:fishy
668:water
613:sebae
566:is a
369:Fusus
274:Murex
194:of a
73:
71:Latin
1288:Crop
1070:Lira
1045:Apex
982:and
937:2011
915:2009
883:help
666:and
652:lit.
644:lit.
634:and
608:and
568:seal
366:and
332:and
109:and
65:The
1065:Lip
827:doi
741:in
723:of
408:not
201:jaw
182:In
97:or
89:or
83:pl.
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