It is a marvel because of the fact that each separate arm has all of the organs necessary for survival. They can regenerate a lost limb and a lost limb can move on it's own, as well as regenerate a whole new starfish in the process of asexual reproduction.
I would say energy myself, and this is because energy plays a key role in all of these. With trophic levels energy is being transferred amongst the levels. Food chain's is a map of how the energy is passed along the chain. Food web is a web of how energy is transferred, and this is why I would say energy is a keyword.
zapped gas/liquid into amino acids
many amino acids thought to have come from meteorites
a mixture of gases and water that Miller thought were present on early Earth was heated and zapped with electricity to mimic lightning. This created five identifiable amino acids
newscientistcom
We know amino acids exist in some kinds of meteorites and interplanetary dust
Many left-handed amino acids were found inside the Murchison meteorite. Most were kinds not found on Earth.
92 different amino acids have been identified in the Murchison meteorite. Of these, only 19 are also found on Earth. The remaining amino acids have no apparent terrestrial source. This discovery led scientists to consider the possibility that Earth's life forms originated elsewhere in the universe. And the same cosmic process that may have helped life arise on Earth could also be seeding life elsewhere in the universe
pbs
https://www.pbs.org/exploringspace/meteorites/murchison/page9.html
Answer:
There are several environmental factors that causes changes in the ecosystem and the population of that area such as invasive species, extreme weather, land use change, pollution and disease.
Lets take invasive species as environmental factor. Introduction of invasive species can cause a huge change in the ecosystem and affects the native population in that area. it increases the competition for food resources and decreases the survival rate of their preys.
For example: Water hyacinth (Eichhornia crassipes). It is an invasive plant species that has very bad impact of native population as well as other population, like it reduces biological diversity, oxygen loss, decreased phytoplankton productivity, eliminate plants that animals use for nesting, and alter animal communities by blocking access to the water.
Thus invasive population can affect population by reducing biodiversity, water shortages, decreasing availability and quality of key natural resources, disturb the food chain and can cause natural calamities.
Invasive species affect the resources that native species are using and that decreases the carrying capacity of the native population as it disturbs the whole food chain.