Vertebrates


What are vertebrates?

    The Animal Kingdom is divided into two major groups: vertebrates and invertebrates. The famous French natural scientist Jean B. Lamarck was the first to make use of such a division of animals at the end of the 18th century. At present we mean by vertebrates the largest subphylum within the phylum Chordates. Vertebrates make up only 3 percent of the more than one million species of animal.


Who belong to vertebrates?

    There are five groups of vertebrates: fishes, amphibians, reptiles, birds and mammals. Each of them forms a systematic unit - a class. However, there is no separate class of the fishes: vertebrates who live in water belonging to different systematic units form this group. One can read about them on the pages of general description of particular group.


How many vertebrates are there in Estonia?

    There are approximately 40,000 species of vertebrates in the world, 484 of them have been found in Estonia. The distribution of Estonian vertebrates is following: fishes - 75 species, amphibians - 11 species, reptiles - 5 species, birds - 328 and mammals - 65 species.


What are the distinctive features of vertebrates?

    The name - vertebrates - refers to the fact that all of them have a vertebra (backbone). In addition to backbone they have skull and several other skeletal bones which form an endoskeleton. All vertebrates are bilaterally symmetrical with two pairs of appendages - limbs, fins, wings, etc. In comparison with invertebrates vertebrates have more developed organ systems. They have higher nervous system, which is divided into central and peripheral nervous system. The parts of the central nervous system - the brain and spinal cord - are in the skull and vertebral column respectively. Circulatory system of vertebrates is closed - i.e. blood circulates in the blood vessels all the time. The heart of different species of vertebrates consists of 2 - 4 parts. The body of vertebrates can be divided into ventral and spinal sides. The body of vertebrates is covered with skin with different outgrowths: scales, hairs, feathers, etc.


Where do vertebrates live?

    Vertebrates live in all kinds of environments. The fishes live only in water. The amphibians mainly live on land but they need water for reproduction. The reptiles can be found in very different environments. Most birds are able to fly. Their nesting places are in forests, on coasts of various bodies of water, in open fields or in populated areas. The mammals also live everywhere: in forests, meadows and water, even under land and in human settlements. Some species of mammals are able to fly.