Clitellum: Difference between revisions

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			{{Short description\|Anatomic feature}}
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	{{Unreferenced\|date=February 2008}}In ]s and some other ], the "clitellum" is a thickened ]ular section of the body wall that secretes a ] in which the eggs are deposited. It is present about 2cm behind the anterior end of the body (around 14th, 15th and 16th segments). Once the eggs have been deposited in the sac, the clitellum slides off the earthworm's body.
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	A clitellum is part of the reproductive system of an annelid (a worm with small rings or segments). The clitellum is a thick, saddle-like, ring found in the epidermis (skin) of the worm. To form a cocoon for its eggs, the clitellum secretes a ] fluid. This organ is used in sexual reproduction of some annelids. The clitellum becomes apparent in mature annelids and may be hard to visually locate in younger annelids. Its color is usually slightly lighter than that of the body of the annelid. Occasionally, living segments of the worm will be shed with the clitellum creating a new worm through regeneration.
			The '''clitellum''' is a thickened ]ular and non-segmented section of the body wall near the head in ]s and ] that secretes a ] in which eggs are stored.<ref name=":0">{{Cite news\|url=https://www.britannica.com/science/animal-reproductive-system/Mechanisms-that-aid-in-the-union-of-gametes#ref606971\|title=animal reproductive system - Mechanisms that aid in the union of gametes\|work=Encyclopedia Britannica\|access-date=2017-08-09\|language=en}}</ref> It is located near the ] end of the body, between the fourteenth and seventeenth segments. The number of the segments to where the clitellum begins and the number of segments that make up the clitellum are important for identifying earthworms.<ref name=":1">{{Cite web\|url=https://www.naturewatch.ca/wormwatch/how-to-guide/anatomy/\|title=NatureWatch - Anatomy of an Earthworm\|website=NatureWatch}}</ref> In ] earthworms, the clitellum has only one layer, resulting in a smaller quantity of eggs than that of the ] earthworms, which have larger multi-layered clitellum that have special cells that secrete ] into the worms' egg sac.<ref>{{cite journal \|last1=Omodeo \|first1=Pietro \|title=Evolution and biogeography of megadriles (Annelida, Clitellata): To Gilberto Righi (1937–1999), in memoriam \|journal=Italian Journal of Zoology \|date=January 2000 \|volume=67 \|issue=2 \|pages=179–201 \|doi=10.1080/11250000009356313 \|s2cid=86293273 \|doi-access=free }} </ref>

			The clitellum is part of the reproductive system of ]s, a subgroup of ]s which contains ] (earthworms) and ] (leeches). The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a cocoon for its eggs, the clitellum secretes a ] fluid.<ref name=":0" /> This organ is used in sexual reproduction of some annelids, such as leeches.
			]'' from North Carolina, South Carolina and Georgia. A, Lake Phelps, NC (Phg-2). Note distinct '''clitellum''' from annulus XIc2 to annulus XIIIb5, as indicated. B, Santee Swamp, SC (Psa-1). Specimen slightly distorted during preservation, showing deep saddle-shaped depression. Note prehensile upper ‘lip’ covering mouth. C, Okefenokee Swamp, GA (Pfl-2). Single star, male gonopore; double star, female gonopore, three annuli posterior to male. Scale bars, 1.0 mm.]]
			In earthworms, the clitellum can only be seen when the worm is sexually mature. It may be white, orange-red or reddish-brown in colour. Earthworms are ready to mate when their clitellum is orange.<ref name=":1" /> In leeches, the clitellum appears during mating season, where it is used for both sexual reproduction and the secretion of a cocoon for the eggs.<ref> {{cite web\| title = Leeches \| publisher = Australian Museum \| url = https://australian.museum/learn/animals/worms/leeches/}} </ref> Its color is usually slightly lighter than that of the body of the annelid. Occasionally, living segments of the worm will be shed with the clitellum.

	==See also==		==See also==
	* ]		* ]

			==References==
			{{reflist}}

			==Further reading==
			*{{cite journal \|last1=Hess \|first1=Roberta T. \|last2=Vena \|first2=Joseph A. \|title=Fine structure of the clitellum of the annelid Enchytraeus fragmentosus \|journal=Tissue and Cell \|date=January 1974 \|volume=6 \|issue=3 \|pages=503–514 \|doi=10.1016/0040-8166(74)90041-x \|pmid=4279471 }}
			*{{cite journal \|last1=Grove \|first1=A. J. \|last2=Cowley \|first2=L. F. \|title=Memoirs: The Relation of the Glandular Elements of the Clitellum of the Brandling Worm (Eisenia foetida, Sav.) to the Secretion of the Cocoon \|journal=Journal of Cell Science \|date=1 May 1927 \|volume=s2-71 \|issue=281 \|pages=31–45 \|doi=10.1242/jcs.s2-71.281.31 }}
			*{{cite journal \|last1=Pavlíček \|first1=Tomáš \|last2=Hadid \|first2=Yarin \|last3=Csuzdi \|first3=Csaba \|title=Opening Pandora's box: Clitellum in phylogeny and taxonomy of earthworms \|journal=Zoology in the Middle East \|date=1 January 2012 \|volume=58 \|issue=sup4 \|pages=31–46 \|doi=10.1080/09397140.2012.10648983 \|s2cid=87652903 }}

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Latest revision as of 19:36, 27 July 2024

Anatomic feature

The clitellum is a thickened glandular and non-segmented section of the body wall near the head in earthworms and leeches that secretes a viscid sac in which eggs are stored. It is located near the anterior end of the body, between the fourteenth and seventeenth segments. The number of the segments to where the clitellum begins and the number of segments that make up the clitellum are important for identifying earthworms. In microdrile earthworms, the clitellum has only one layer, resulting in a smaller quantity of eggs than that of the megadrile earthworms, which have larger multi-layered clitellum that have special cells that secrete albumin into the worms' egg sac.

The clitellum is part of the reproductive system of clitellates, a subgroup of annelids which contains oligochaetes (earthworms) and hirudineans (leeches). The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a cocoon for its eggs, the clitellum secretes a viscous fluid. This organ is used in sexual reproduction of some annelids, such as leeches.

In earthworms, the clitellum can only be seen when the worm is sexually mature. It may be white, orange-red or reddish-brown in colour. Earthworms are ready to mate when their clitellum is orange. In leeches, the clitellum appears during mating season, where it is used for both sexual reproduction and the secretion of a cocoon for the eggs. Its color is usually slightly lighter than that of the body of the annelid. Occasionally, living segments of the worm will be shed with the clitellum.

References

^ "animal reproductive system - Mechanisms that aid in the union of gametes". Encyclopedia Britannica. Retrieved 2017-08-09.
^ "NatureWatch - Anatomy of an Earthworm". NatureWatch.
Omodeo, Pietro (January 2000). "Evolution and biogeography of megadriles (Annelida, Clitellata): To Gilberto Righi (1937–1999), in memoriam". Italian Journal of Zoology. 67 (2): 179–201. doi:10.1080/11250000009356313. S2CID 86293273.
"Leeches". Australian Museum.

Latest revision as of 19:36, 27 July 2024

See also

References

Further reading