interesting facts about: animals
Volvox is a kind of chlorophytes, a genus of green algae. This creature forms spherical colonies rating more than 50,000 cells. They live in a lot of freshwater environments, and were first analyzed by Antonie van Leeuwenhoek in 1700.
Ancestors of Volvox underwent from single cells to form multicellular colonies more than 200 million years ago, in the times of the Triassic period. Using of DNA sequences from about 45 various species of Volvox and related genes it was suggested that the transition from single cells to undistinguished polycellular colonies took approximately 40 million years.
Volvox is the most evolved in a series of genus that can form spherical colonies. Each mature Volvox colony represents composed of numerous flagellate bodies of cells similar to Chlamydomonas, up to 50 thousands in entire, and embedded in the surface of a hollow sphere or coenobium containing an extracellular matrix made of a specific gelatinous protein with glue features.
Exclude during the creation of daughter colonies, vegetative Volvox cells comprise a single stratum with the flagella facing outside. The cells swim in a specific coordinated way, with distinct posterior and anterior sights. The cells have special eyespots, more developed near the anterior, which enable the Volvox colony to move in water towards the source of light.
The individual species of algae are interrelated by thin strings of cytoplasm, named protoplasmates. They are recognized to demonstrate some individuality and working for the benefit of their colony and being managers of one multicellular organism.
An asexual colony includes both somatic (and vegetative) cells, which do not reproduce but feed the colony, and gonidia (near the posterior), which reproduce new cells through repeated division. The daughter colonies are initially held inside the parent coenobium and have their flagella oriented inwards. Further, the parent disintegrates and the daughter colonies invert. In sexual reproduction two sorts of gametes are produced. Volvox cells can be monoecious or dioecious. Male colonies release millions of microgametes, or sperm, while in female colonies single cells expand to get oogametes, or protoeggs. The fact: the principle of Volvox colonies organization serves as an argument against Darwin`s Evolution theory.