The animals that inhabit our planet have a great variety of shapes and sizes. Some live in the terrestrial environment, others in the sea and there are some who can fly. The diversity of species requires that they must be ordered and classified in some way.
In the animal kingdom there are two large groups of beings. Vertebrates and invertebrates. The former are those who have bones inside their body, as well as a spinal column that is the basic element of their internal structure. There are five types of vertebrates: fish, reptiles, amphibians, birds, and mammals.
Invertebrate animals are those that do not have a bone structure inside them and therefore do not have a backbone. They are generally smaller than vertebrates and represent the vast majority of all animals, with more than 90% of the total. One of their common characteristics is that they reproduce through eggs (they are oviparous). They emerged in the early stages of life formation on Earth and their initial habitat was water. They were rapidly expanding due to their great adaptability. Over time they occupied the different media, so that in addition to the aquatic, they live on Earth or in the air.
Invertebrates are essential within the food chain of other animals considered primary within the order of classification. Biologists use 6 different edges to order invertebrates (vertebrates have only one edge, that of chordates). The most abundant invertebrates are insects (bees, wasps, ants, flies, fleas and a long etcetera). Scientists say insects can be the food of the future for humanity.
Mollusks also belong to this category and some of them are squid, clams or octopuses. Sponges, most of which live in salt water, are equally invertebrates. Formerly they were considered plants, but it was discovered that their internal mechanisms were from the kingdom of animals.
The coelenterates (corals, jellyfish or anemones) are also invertebrates. The great diversity of invertebrates is one of the branches of classification of animals. It receives the name of Animalia (animal kingdom in Latin). The first classification was made by Aristotle in the 15th century BC. C and it remained until Linnaeus (eighteenth century) introduced a new system by hierarchical ranges, ranging from the most general to the most concrete.