What are the main environmental roles?

There are many ecological roles. These include microscopic, small, medium and large herbivores, manufacturers, predators, gadgets and parasites. On the planet today is an estimated 7 million plant and animal species, most of them insects, occupying every conceivable niche. The most popular niches seem to be herbivore and parasite, with predators are the smallest niche. However, it also seems that among all ecological roles, Predator captures the popular imagination most. Some paleontologists assumed that the development of predation was partly responsible for the evolutionary diversification that occurred during Cambrian. In any case, at the end of Cambrian, all the main ecological roles were filled, except for the largest organisms, only the meter length. Over the next period, Ordovik, several animals (such as nautiloids) developed 3.5 m (11.6 ft), and the carbon size of the size was similar to today's.

Although animals are generally highly specialized in their ecological roles, some animals share roles and some evolutionary lines can develop from one ecological role to another. For example, the ancestors of the whales have evolved from the middle predators of ground land on the water filter of the water filter. Predators have evolved from herbivores and many predators are also gadgets. Many predators become big and hard not only to take off the prey, but also to compete with other large predators for a captured killing. The upper size of the predators is determined by the amount of prey available. In excellent evolutionary circumstances, such as those that have experienced Crocodilian Predators in Swamps from time to time, predators can be a balloon up to huge sizes, up to seven times larger than their recent ancestors.

ecological niches work in a pyramid -based format, with producers such as plants at the bottom, herbivores in the middle and predators above, with predators of peaks like tigers at the top. The higher the animal on the pyremGenus, the less biomass is generally devoted to this species and thus rarer. Animals high on the pyramid are generally more susceptible to extinction, but not always. In some historical dying, where most of the plant lives were erased, the animals that survived were gadgets rather than devoted herbivores or carnivores.