It is mainly divided into three categories: animals, plants and microorganisms.
I. Animals
Animals are divided into invertebrates and vertebrates. Scientists have identified more than 46,900 species of vertebrates. Including carp, yellow croaker and other fish animals, reptiles such as snakes and lizards, amphibians such as frogs and giant salamanders, and mammals such as birds and red pandas.
Scientists have also discovered more than 654.38+300,000 species of invertebrates. Most of these animals are insects, most of which are beetles. Slugs, earthworms, squid, oysters, red starfish, jellyfish, spiders, corals, radiolarians, roundworms, pork tapeworms, worms, snails and slugs all belong to invertebrates.
The bodies of all members of the animal kingdom are heterotrophs composed of cells.
Second, plants
In nature, all living things belong to living things. Organisms should be divided into several realms. Organisms with fixed autotrophic life are called plant realms, or plants for short.
Plants have six organs: roots, stems, leaves, flowers, fruits and seeds. The stem is the axis of a plant. Erect or crawling in water, with branches on the stem and meristems at the top of the branches for the top to grow. Stems usually differentiate into short nodes and long nodes. Stem has the function of transporting nutrients and water and supporting leaves, flowers and fruits in a certain space. Some stems also have the functions of photosynthesis, nutrition storage and reproduction. Leaves are one of the vegetative organs of vascular plants. Its function is to synthesize organic matter through photosynthesis, and it has transpiration to provide roots with the power to absorb water and mineral nutrients from the outside. Flowers are unusually short branches with reproductive function. Fruit is mainly used as a medium for spreading seeds. Seeds have the function of reproduction and reproduction, and they also have various structures suitable for reproduction or resistance to adversity, which creates good conditions for the continuation of plant races.
Third, microorganisms.
All microorganisms that are difficult for an individual to observe with the naked eye. Microorganisms include bacteria, viruses, fungi and some algae. (But some microorganisms are visible to the naked eye, such as mushrooms and ganoderma lucidum, which belong to fungi. )
Virus is a kind of "cell-free organism" composed of a few components such as nucleic acid and protein, but its survival depends on living cells. According to the different environment, it can be divided into space microorganisms and marine microorganisms. According to the cell structure, it can be divided into prokaryotic microorganisms and eukaryotic microorganisms.
* * * creatures
However, it is very difficult to scientifically define "life". So far, there is no definition of life accepted by most scientists. But from the complicated life phenomena, we can still find the * * * characteristics of some creatures, that is, the basic characteristics of life:
① Except viruses, they are all composed of cells and cell products.
② Life shows a tight structure and a high degree of order.
③ It has metabolic function.
(4) Being under pressure and able to adapt to and influence the environment.
⑤ It has the characteristics of growth, development and reproduction.
⑥ It has the characteristics of heredity and variation. Biology refers to a living body that can live independently. Including animals, plants, microorganisms, etc.
All landowners living things need nutrition.
8 creatures can breathe.