Vertebrates

Vertebrates, or cranial (Vertebrate, or Craniata),is one of the subtypes of type chordates (Chordata). Unlike the so-called invertebrates that are not specific systematic category and other representatives of the type chordate, Vertebrates characterized by a more complex organization of all organ systems. Most of P. the body is divided into three parts: head, body and tail, and terrestrial vertebrates segregated fourth Department - neck; on the body are formed paired appendages - the bodies of the movement of the leg. In the inner skeleton P. (except the lowest fish) in the development process chord displaced vertebrae, in the anterior segregated skull. CNS at P. consists of the brain and spinal cord. The circulatory system of the closed type and consists of blood vessels and the heart that causes blood in motion.
Subtype vertebrate divided into 6 classes: cyclostomes, or jawless (Agnatha), fish (Pisces), amphibians (Amphibia), reptiles (Reptilia)birds (Aves) mammals (Mammalia). The first two classes - aquatic vertebrates, the rest of terrestrial vertebrates. These are characterized by the absence of the jaws and paired appendages, typical Gill bags, cartilaginous skeleton and a constant chord. Fish (see) have paired and unpaired fins; Gill are located outside of the Gill arches, two-chamber heart, skeletal cartilage or bone. Amphibians breathe in larval state gills, adult breathe the light and the surface of the skin, heart, three -, five-toed limbs. Reptiles have a Horny covering from scales and plates, breathing, lung, heart, most three-chamber with two circular arcs of the aorta. In birds (see) forequarters transformed into wings, the body is covered with feathers, there are a number of morphological features as a consequence of adaptation of birds to fly; four-chamber heart, with one (right) arch of aorta. Body temperature constant. For mammals (see) characteristic: hair, skin breast for feeding of young, well-developed nervous system, teeth differentiated on the incisors, canines and indigenous, four-chamber heart with one (left) arch of aorta, a constant body temperature. Many of vertebrates (fish, birds, mammals) are used for human food sources and other valuable products (see Pets, food animals). A number of P. brings harm to humans or poisonous animals (see) - reptiles, some fish,or as sources of disease agents [fish, birds, mammals, especially rodents (see)]. Cm. also Zoonoses.