Describe the four main spheres of earth. 1. lithosphere: 2. hydrosphere: 3. atmosphere: 4. biosphere:

The four main spheres of Earth are as follows:  

1. Lithosphere: It is also called geosphere and is formed of the core of the Earth, the crust, mantle, ocean floor, sand, mountains, asphalt, rocks, and others.  

2. Hydrosphere: It is formed of everything that comprises water like rivers, oceans, lakes, rain, snow, and ice caps.  

3. Atmosphere: It is formed of gases like hydrogen, oxygen, water vapor, the wind, and the ozone.  

4. Biosphere: It comprises all the living components like animals, plants, humans, microbes, insects, and others.  

answer: 20 percent

the fish culture has become a developing commercial practice in developing countries which is already prominent in developed countries of the world. the major fish protein demand is being supplemented in developing countries is   fishing to meet the needs of the growing population. therefore, in some developing nations, the percentage of animal protein from fish in the diet can be as high as 20 percent.