All living organisms on the planet can be divided into two main categories: vertebrates and invertebrates. As the name implies, it can be understood that the main difference between these two groups is the presence of the spine. Worms and insects do not have it, while people, birds and other vertebrates exist thanks to him.
Characteristic of vertebrates and invertebrates
Scientists believe that vertebrates occurred during the evolution of invertebrates due to changes in the surrounding space. But it is precisely because of this that the vertebrates received a more effective system to organize the structure of the body and the ability to adapt to any habitat (water, air atmosphere or land).
Despite the simpler structure of the organization, vertebrates have more modest sizes, when compared with vertebrates (and the size of these organisms can vary from small to large ones). Today, scientists have identified more than two million species of invertebrates, which make up about 98% of the total number of living organisms identified in the animal kingdom.
If we talk about invertebrates, then these organisms, for obvious reasons, do not have an organized and developed system of skeleton, chord, and in most cases also the nervous system. But the vertebrates have a segmented and rather mobile spinal column along with a special nervous, digestive and respiratory system organized in a special way.
Differences between two groups of organisms
The key differences that are customary to distinguish among the vertebral and invertebrate types of organisms are:
So, the vertebrates are divided into only five detachments, ranging from fish to mammals. But science refers to invertebrates a huge number of detachments: from sponges, intestinal to echinoderms, worms and mollusks.
Vertebrates and invertebrates, first of all, differ in their size: the first tiny and slow, as they do not have the ways of supporting the body (with rare exceptions), while vertebrates are distinguished by the ability to develop more actively.
Vertebrates have many specialized systems that help them respond quickly to any changes, but invertebrates act instinctively, since they are devoid of the nervous (and any other) system.
Similarities of two groups of organisms
Signs of similarity of the two main groups of living organisms can be considered:
A feature that united all representatives of the chordal (both vertebrates and invertebrates) is the presence of a flexible supporting rod, called Hord, at some moment of development. In vertebrates, it is replaced by a series of bones at an early stage of development, and this is how the spine turns out.