Arcella

Watch-glass ( Arcella )

The watch-glass ( Arcella ), also Uhrglastiere or Uhrglastierchen, are a genus of Arcellinida.

Features

Like all amoebas, they have a shell of a housing ungekammertes framework substance of organic material ( structural proteins ) consists. In contrast to other genera no gravel chips or other foreign bodies to reinforce the housing to be installed. The cup-like casing reminiscent of a watch glass. The housing has a diameter up to 0.17 mm and a height of up to 0.07 mm. In the plan under the microscope this case appears mostly round, with a central opening. The brownish color of the curved shells is formed by the progressive with increasing age storage of iron and manganese compounds.

Most species have two nuclei, some more, the loudmouthed aspect Uhrglastier ( Arcella megastoma ) has up to 200. There are several contractile vacuoles present. The cell is anchored to the casing wall, the housing but not completely fill. The cysts are round and are located within the housing.

Dissemination

The unicellular world live in fresh water, even in eutrophic waters in bogs or even on wet leaves. They are also found in wet and dry moss, a few species also live terrestrial. They eat mostly herbivorous.

Systematics and species ( selection)

Type species is the Common Uhrglastier ( Arcella vulgaris). Verkieste fossils that are assigned to the genus Arcella, are known since the Paleozoic and were for example found in the coal of the Ruhr. A recently are currently around 50 species and numerous varieties and forms are known, including:

• Mean Uhrglastier ( Arcella vulgaris)
• Buckeliges Uhrglastier ( Arcella gibbosa )
• Arcella hemisphaerica
• Pyramid Uhrglastier ( Arcella conica )
• Serrated Uhrglastier ( Arcella dentata )
• Teller Uhrglastier ( Arcella artocrea )
• Disc Uhrglastier ( Arcella discoid )
• Großmäuliges Uhrglastier ( Arcella megastoma )

Evidence