The primitive food chain is mutually exclusive, so that different species can continue to survive in nature, piranhas have a nemesis even if they are fierce.

Water bears are the common name for retarded animals, and these creatures are so small that their body length is usually no more than 1 mm, so we usually do not notice their presence.

Species invasions are actually a very common occurrence on a global scale. Although there are countless species of organisms on the planet, these are distributed all over the world, with some species being endemic to certain areas and not present in others, and others having a relatively wide distribution. When some species appear in places where they would not have previously existed, this is when the species may become invasive.