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Multicellular organisms, especially long-living animals, face the challenge of cancer, which occurs when cells fail to regulate their growth within the normal program of development. Changes in tissue morphology can be observed during this process.
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ ˌ æ n ɪ ˈ m eɪ l i ə / [4]).With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ ˌ æ n ɪ ˈ m eɪ l i ə /).With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
Animals are multicellular eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development.
In complex multicellular organisms, cells specialize into different cell types that are adapted to particular functions. In mammals, major cell types include skin cells , muscle cells , neurons , blood cells , fibroblasts , stem cells , and others.
The multicellular eukaryotes include the animals, plants, and fungi, but again, these groups too contain many unicellular species. [11] Eukaryotic cells are typically much larger than those of prokaryotes —the bacteria and the archaea —having a volume of around 10,000 times greater.
Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues [10] and organs. [11] Some of them are radially symmetrical, but most are asymmetrical.
Colonial organisms may have been the first step toward multicellular organisms. [9] Individuals within a multicellular colonial organism may be called ramets , modules , or zooids . Structural and functional variation ( polymorphism ), when present, designates ramet responsibilities such as feeding, reproduction, and defense.