Volvox aureus

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Volvox aureus
Volvox aureus Figure 1: Colony with multiplication cells Figure 2: Colony with daughter colonies Figure 3: Dead colony that has released its daughter colonies

Volvox aureus
Figure 1: Colony with multiplication cells
Figure 2: Colony with daughter colonies
Figure 3: Dead colony that has released its daughter colonies

Systematics
without rank: Chlorophyta
without rank: Chlorophyceae
Order : Volvocales
Family : Volvocaceae
Genre : Volvox
Type : Volvox aureus
Scientific name
Volvox aureus
Ehrenberg , 1832

Volvox aureus is a species of the genus Volvox from the class Chlorophyceae .

description

Volvox aureus forms spherical colonies (diameter of approx. 0.5 mm) from at least 200 to a maximum of 3,200 individual cells (diameter of five to eight µm). When viewed from above, the individual cells are almost circular and are connected to one another with fine plasma threads or plasma bundles. Their chloroplasts are large, trough-shaped, and confined to the center of the cells. There are only two contractile vacuoles within the cells . When viewed from the side, the cells are egg-shaped and not as densely packed as in the case of Volvox globator . The two flagella of each cell emerge through fine openings in the very thin Grenzgallert lamella. The gelatinous columns of the individual cells converge to form a common gelatinous layer just below the boundary lamella; the honeycomb fields are therefore less pronounced than in Vaucheria globator . Four to ten multiplication cells are stored in the rear half of the sphere.

Reproduction

During asexual reproduction , the gonidia divide multiple times and form a hollow sphere of cells, the flagellum poles of which point into the interior of the hollow sphere. By inversion, the colony turns its inside outwards. The daughter colonies are released when the mother colony dies.

The sexual reproduction is done by egg fertilization (oogamy). Volvox aureus is dioecious, i. H. there are male and female colonies. Tabular packets of spermatozoids are released from male colonies; female colonies form spherical egg cells. After fertilization, a brown-red colored, ornamented permanent zygote with a smooth cell membrane develops . The zygote germinates by reduction division .

distribution

Volvox aureus lives in stagnant eutrophic waters . During the day the colonies are more on the surface, at night they sink into deeper layers.

Related species (selection)

swell

  • Karl-Heinz Linne von Berg, Michael Melkonian u. a .: The Kosmos algae guide. The most important freshwater algae under the microscope. Kosmos, Stuttgart 2004, ISBN 3-440-09719-6 .
  • Heinz Streble , Dieter Krauter : Life in a drop of water. Microflora and microfauna of freshwater. An identification book. 10th edition. Kosmos, Stuttgart 2006, ISBN 3-440-10807-4 .

Web links

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