變形蟲

此條目介紹的是单细胞原生动物。关于一类能改变形状的机体或细胞，请见「变形体」。

变形虫属
科学分类 编辑
门： 變形蟲門 Amoebozoa
纲： 根足纲 Rhizopodea
目： 变形目 Amoebida
科： 變形蟲科 Amoebidae
属： 变形虫属 Amoeba
Bory de Saint-Vincent, 1822
物种

见正文

變形蟲（學名：Amoeba）音译阿米巴，是變形蟲屬的泛稱，也作阿米巴原虫、阿米巴變形蟲、阿米巴虫[註 1]，为一种单细胞原生动物，可以根据需要改變體形，因而得名。变形虫以往是分類於原生生物界，現則獨立歸於變形蟲門（Phylum Amoebozoa）。

分布

在清水池塘、水流緩慢藻類較多的淺水中，还有泥土中都可以找到它，亦可成寄生蟲寄生在其他生物裡面。

历史

变形虫首先在1757年由德国自然学家奥古斯都·冯·卢森霍夫（英语：August Johann Rösel von Rosenhof）在显微镜下观察到[1]。早期自然学家因其能改变身体形状，故用希腊神话中可以变形的普罗透斯（Proteus）的名字将其命名为Proteus animalcule，后来法国自然学家简·文森特（英语：Jean Baptiste Bory de Saint-Vincent）用希腊文中的“变”（amoibè (αμοιβή））命名其为"amibe"[2][3]。

解剖学

阿米巴解剖学示意图

阿米巴的细胞器和细胞质都包裹在细胞膜中，沒有固定的形状，能在全身各處伸出偽足来運動和攝食。大变形虫在运动时长220-749微米[4]，在变形虫中是很大的[5]。它是异养生物，通过吞噬作用进食。一般是以單細胞藻類、小型單細胞動物為食物。當它碰到食物時會伸出偽足進行包圍，然后分泌消化酶将食物消化。不能消化的物質，就會通過質膜排出體外，稱排遺。變形蟲利用呼吸作用得到能量，吸入的氧和排出的二氧化碳的工作都由細胞膜負責。

变形虫在显微镜下的显著特征是有一个或多个细胞核、伸縮泡及食物泡。伸縮泡作用是排除變形蟲體內過多水分，保持渗透压平衡；食物泡的功能則是储存和消化食物養分。其繁殖方式主要藉由有丝分裂和细胞质分裂，而非像一般细菌那样进行二分裂生殖。遺傳功能由細胞核負責，如果变形虫被切成两半，则保有细胞核的一半能长成一个完整的变形虫，另一半会死去。[6]

繁殖

过去认为无性生殖是变形虫的一个特性，但近来科学家发现它也能进行有性生殖[7]。而且科学家发现变形虫在古代可能是有性生殖占主流，而无性生殖是近代流行起来的[8]。

下属分类

本科包括以下属：[9]

相关疾病

阿米巴原虫脑炎是一种罕见但严重的疾病，由阿米巴原虫（一种单细胞寄生虫）引起。这种疾病主要通过进食被感染的水或食物而传播，在野外水域活动时阿米巴原虫经口鼻等进入人体也会致病。它会导致脑部感染，引起头痛、发热、恶心、呕吐等症状，并可能导致严重的神经系统损害甚至死亡。及早发现和治疗至关重要。

影像资料

运动中的大变形虫
变形虫吞噬硅藻

[10]

外部連結

  • The Amoebae website brings together information from published sources.

参考资料

  1. ^ Leidy, Joseph. Amoeba proteus. The American Naturalist. 1878, 12 (4): 235–8. JSTOR 2463786. doi:10.1086/272082. 
  2. ^ Audouin, Jean-Victor; et al. Dictionnaire classique d'histoire naturelle. Rey et Gravier. 1826: 5. 
  3. ^ McGrath, Kimberley; Blachford, Stacey (编). Gale Encyclopedia of Science Vol. 1: Aardvark-Catalyst 2nd. Gale Group. 2001. ISBN 0-7876-4370-X. OCLC 46337140. 
  4. ^ Amoeba proteus. Amoebae on the Web. [2009-10-08]. （原始内容存档于2013-01-13）. 
  5. ^ MacIver, Sutherland. Isolation of Amoebae. The Amoebae. [2009-10-08]. （原始内容存档于2009-09-30）. 
  6. ^ Amoeba. Scienceclarified.com. [2013-06-08]. （原始内容存档于2007-12-25）. 
  7. ^ Hurst LD, Hamilton WD, Ladle RJ. Covert sex. Trends Ecol. Evol. (Amst.). May 1992, 7 (5): 144–5 [2013-06-08]. PMID 21235987. doi:10.1016/0169-5347(92)90205-P. （原始内容存档于2019-05-04）. 
  8. ^ Lahr DJ, Parfrey LW, Mitchell EA, Katz LA, Lara E. The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms. Proc. Biol. Sci. July 2011, 278 (1715): 2081–90. PMC 3107637 可免费查阅. PMID 21429931. doi:10.1098/rspb.2011.0289. 
  9. ^ Amoeba Ehrenberg, 1830. GBIF. [2023-04-30]. （原始内容存档于2023-05-03）. 
  10. ^ Chakraborty, P. Amoebae. Textbook of medical parasitology 2nd. New Central Book Agency. 2004: 15. ISBN 8173814570. 

注释

  1. ^ 需要注意的是，俗稱「食腦蟲」的福氏內格里蟲並不屬於變形蟲，只是其在環境適於它生存時，會以類阿米巴的形式存在，故被各國媒體誤認為是變形蟲的一種，甚至被有些人誤作為變形蟲的別稱。

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