Some general characteristics of animals
Animals are eater or user of the earth. They are heterotrophs and rely directly or indirectly on plants, photosynthetic protists (algae), or autotrophic bacteria for breeding. Animals can go from place to place in search of food. In most cases, food is absorbed into the inner cavity after digestion.
All animals are multicellular heterotrophs. A unicellular heterotrophic organism called protozoa, once considered a simple animal, is now considered the king of the large and diverse group, the Protestants.
Different in form
Almost all animals (99%) are invertebrates, lacking in waist Of the estimated 10 million living animal species, only 42,500 have a spinal cord and are referred to as chimpanzees. The animal kingdom includes about 35 species of fila, most of which are found in the ocean. So-and-so is rarely found in freshwater and is still rarely found on land. The life on earth is dominated by the three elephants in the arthropods (spiders and insects), mollusks (cheap) and cordates (vertebrates).
There are no cell walls.
In multicellular organisms, animal cells are distinct, because they have no hard and often very flexible cell walls.
Animals’ ability to move faster and in more complex ways than members of other states is perhaps their most striking feature, and is related to the flexibility of their cells and the evolution of nerve and muscle tissue.
Most animals reproduce sexually. Animal eggs, which are non-stimulating, are smaller, usually larger than flagellate semen. In animals, cells formed in meiosis act as direct solutions. Haploid cells do not first divide by mitosis, as they do in plants and fungi, but fuse directly with each other to form a zygote.
Most animals have a similar pattern of fetal development. The zygote first operates a series of mitotic divisions, called morula, and it consists of a solid cell of cells, the morula, then the hollow ball of cells, the blastula. In most animals, the blastula folds together to form a hollow sac with an opening at one end called the blastopore. At this stage the fetus is called gastroenteritis.
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