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ⓘ Multicellular organism. Multi-cellular organisms are organisms with more than one cell. This is the case for animals, plants and most fungi. In such organisms, ..




Multicellular organism
                                     

ⓘ Multicellular organism

Multi-cellular organisms are organisms with more than one cell. This is the case for animals, plants and most fungi. In such organisms, cells are usually specialised. All the cells with the same function work together. Such a group of cells is then called a tissue.

Multi-cellular organisms have a set of cells that specialize in reproduction. Reproduction in such organisms is usually sexual. The sex cells are either sperm or ovum also named "egg" cells. If they are sperm cells, the organism is male, if they are egg cells it is female. If both are present, the organism is a hermaphrodite.

                                     

1. Evolutionary history

We know, from their cell structure, that multicellularity has evolved independently many times in Earth history, for example in plants and animals. The earliest forms of life in the fossil record are cyanobacteria from the Archaean era at 3.5 billion years ago. They grew as single cells but lived in colonies as stromatolites.

The first multicellular fossils have been found in 2.1 billion years old Palaeoproterozoic rocks from the Gabon in Africa. These are eukaryotic cells which live colonially. The fossils are visible to the naked eye, and hence much larger than bacteria. The authors comment that one advantage of multicellularity is larger size, and that an adequate level of oxygen is required to support this kind of life.

                                     

2. Consequences of multicellularity

To reproduce, multicellular organisms must solve the problem of regenerating a whole organism from germ cells i.e. sperm and egg cells, an issue that is studied in developmental biology.

Multicellular organisms, especially long-living animals, also face the challenge of cancer, which occurs when cells fail to regulate their growth within the normal program of development.

                                     
  • complete organism but for the moment it is switched off. Some organisms are made up of millions of cells. They are multicellular organisms Many can
  • the oldest known sexually reproducing organism and therefore the earliest known complex multicellular organism Butterfield N.J. 2000. Bangiomorpha pubescens
  • with a microscope or anything that enhances images. Life timeline Multicellular organisms Microorganism About the kingdom Protista Archived 2012 - 05 - 10 at
  • trillions of cells. All plants and animals are multicellular organisms The cells of a multicellular organism are not all the same. They have different shapes
  • organisms like Amoebozoa, one cell division reproduces the entire organism On a larger scale, cell division can create offspring from multicellular organisms
  • overall shape of the body and its parts. The body plans of most multicellular organisms have some form of symmetry, radial symmetry, bilateral symmetry
  • micro - organisms are unicellular organism with only one cell, but there are unicellular protists that are visible to the human eye, and some multicellular species
  • or organism It is only used for organisms which are in one part or whole. There are organisms which change from single cells to whole organisms for
  • the microfossils of the multicellular filaments of Bangiomorpha pubescens a type of red algae This was the first organism that had sexual reproduction