Ecosystems

The physical environment of an ecosystem usually provides sunlight, water, nutrients, gasses like oxygen and carbon dioxide, and some types of shelter.

All energy originates in the Sun. Solar energy is

Organisms classified as ‘primary producers’ capture energy and nutrients directly from this environment (almost always they are plants, but we needed a different term to try and cover all the variety and exceptions in the world’s diverse ecosystems).

Using the energy provided by sunlight and instructions provided from their genes, they chemically reconfigure nutrients into their own structures for growth and reproduction, like roots, leaves, branches, sap, and flowers, honey, pollen, seeds, and nuts.

// Plants who successfully grow to maturity use sexual reproduction; mixing their genes with other successful plants and passing them onto the next generation. This allows their population to adapt to a changing environment.

There is often such an abundance of plants that the concentrated nutrients and energy they’ve collected can support populations of other, radically different creatures.

They are ‘primary consumers’, commonly called herbivores. They’re animals who rely on putting large volumes of plant matter through baths of stomach acid and a long digestive tract. This is a destructive process which extracts nutrition and energy from the plants and utilises them to build their own bodies.

‘Secondary consumers’ eat herbivores, making use of more nutritious and easily digested animal cells, and 'tertiary consumers’ eat the secondary consumers. Both are known as carnivores, and because energy and nutrition has been concentrated, they don't have to eat as much or as frequently.

This creates a multilevel ‘trophic pyramid’ where each level is supported by the levels below it. Just as the first level of animals are entirely dependent on plants to transform nutrients from their surrounding environment into digestible material they can use, so ‘higher’ levels depend on herbivores, and so on. Therefore there tends to be huge populations of plants, large populations of herbivores, and only modest populations of tertiary consumers who depend on a large and healthy ecosystem.

But real ecosystems tend to have a bit more chaos and complexity. Many animals eat both plants and other animals (known as omnivores), where secondary consumers will prey on the young of tertiary consumers, and even primary consumers have been known to opportunistically eat meat. So most ecosystems are more of a complex web than a simple pyramid.

This fundamental structure of the ‘food’ web underscores every ecosystem. There is interdependence between all organisms in an ecosystem, which creates niches that species evolve to exploit, often radically altering their bodies to better exploit it.

So every ecosystem is an elaborate flow of nutrients of which its creatures are entirely comprised.

But each individual organism has its own priorities. To survive and maximise its own genes in its species gene pool.