外套膜

外套膜英語:拉丁語,形容詞形式:,本義指長袍),或簡稱作套膜,是軟體動物腕足動物被囊动物的重要解剖部分,由其背侧的体壁向下褶與伸展形成,經常包裹整个内脏团;而内脏囊與外套膜之間的空腔即为外套膜腔外套腔()[1]。外套腔是許多器官的開口,如肛門鰓孔肾孔生殖孔[2]

欧洲乌贼Loligo vulgaris)的外套膜就是頭部以後的所有可見部份,即外體壁及在其上的鰭。
大硨磲的外套膜有着鮮豔的顏色,可以保護大硨磲不受猛烈陽光曬傷。
墨鱼利用牠們的外套膜腔作噴射推進

外套膜腔

軟體動物祖先的假想解剖圖。軟體動物的身體主要可分為头、足、内脏团3個部分,部分生物還具有從外套膜形成的殼[1]

「外套膜腔」是軟體動物生物學的一個中心特徵,由外套膜的裙邊,即外套膜上一個由其雙重皺摺包裹起來的液體空間融形成。這個空間藏有軟體動物的肛门osphradium腎孔生殖孔

不同物種的外套膜腔會作不同的變化。對於大多數軟體動物來說,牠們的外套膜腔以牠們的呼吸器官運作:特別是在腹足綱真有肺類物種,外套膜腔更特化成外套膜肺();雙殼綱生物整個柔軟生體都在擴大的外套膜腔內[3],包括其「外殼」,但其外套膜腔的主要功用在進食方面。In some molluscs the mantle cavity is a brood chamber, and in 头足纲 and some bivalves such as scallops, it is a locomotory organ. 在多類物種中,牠們的外套膜的上皮細胞都能分泌出碳酸鈣貝殼素,並形成軟體動物的外殼。而在海蛞蝓,由於其外殼基本上已退化,其外套膜成為了動物的背部表面。

The mantle is highly muscular. In cephalopods the contraction of the mantle is used to force water through a tubular siphon, the 虹管, and this propels the animal very rapidly through the water. In gastropods it is used as a kind of "foot" for locomotion over the surface. In 歐洲帽貝屬 the foot includes the entire ventral surface of the animal. The foot of the 双壳纲 is a fleshy process adapted by its form to digging rather than to locomotion.

頭足類的神经系统是除了脊椎动物以外的有體腔動物當中最複雜的。頭足類的外套膜有的巨大神經纖維是神經生理学最合適的實驗材料。

Formation of mollusc shell

In shelled molluscs, the mantle is the organ that forms the shell, and adds to the shell to increase its size and strength as the animal grows. Shell material is secreted by the 外胚层ic (上皮組織) 细胞 of the mantle tissue.[4]

腹足綱物種的外套膜

不少腹足綱物種的外套膜都藏在其螺殼裡。以下圖片為一些例子:

In species where the shell is small compared to the size of the body, more of the mantle shows. Shell-less 蛞蝓s have the mantle fully visible. The dorsal surface of the mantle is called the notum, while the ventral surface of the mantle is called the hyponotum. In the family Philomycidae, the mantle covers the whole back side of the body.[5]

Photo of 驴耳鲍螺 with the shell removed.
This drawing shows that the mantle (in gray) covers the majority of the dorsal surface of the animal.[6]

軟體動物,除了依靠牠們的口蓋之外,還可以透過分泌黏液來防止乾燥和掠食者。

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參考文獻

  1. . 藍色動物學. [2017-05-09] (中文(简体)‎).
  2. Ruppert, E.E.; Fox, R.S.; Barnes, R.D. 7. Brooks / Cole. 2004: 284–291. ISBN 0-03-025982-7.
  3. Hayward, PJ. . Oxford University Press. 1996: 484–628. ISBN 0-19-854055-8.
  4. "integument (molluscs)." Encyclopædia Britannica. 2009. 大英百科全书
  5. Tsai C.-L. & Wu S.-K. (2008). PDF "A New Meghimatium Slug (Pulmonata: Philomycidae) from Taiwan". Zoological Studies 47(6): 759-766.
  6. Daniel J Jackson, Carmel McDougall, Kathryn Green, Fiona Simpson, Gert Wörheide & Bernard M Degnan. 2006. http://www.biomedcentral.com/1741-7007/4/40 A rapidly evolving secretome builds and patterns a sea shell]. BMC Biology 2006, 4:4. 0 doi:10.1186/1741-7007-4-40.
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