Because they find skeleton of animals of a certain species that died roughly around the same time and place. <span />
Answer:The inward flow of sodium ions increases the concentration of positively charged cations in the cell and causes depolarization, where the potential of the cell is higher than the cell's resting potential.
Explanation:
Sea stars I hope this helps somewhat ^^;
Answer: Chemical spills.
A pollution is a phenomena which disturbs the natural composition of the environmental factors such as air, water and soil. A pollutant is a component which disturbs the original quality of the environmental factors. Chemical spills is a pollutant which consist of toxic or non-toxic chemical being added up by factories, water transportation and agricultural irrigation, pesticide or herbicides to soil, water and air. The chemical spill when sprayed on the plants kill the insects, when dissolved in water body kill aquatic animals. The effect is seen mostly in higher trophic level organisms because of biomagnification. Biomagnification is a phenomena in which an undigestable toxic substance enters into the food chain when one organism being eaten up by other. At the top higher level of the food chain accumulates toxic substances from chemical spill and results in death and extinction of species. Therefore, causes loss of biodiversity from the ecosystem.