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The reptilian nervous system contains the same basic part of the amphibian brain, but the reptile cerebrum and cerebellum are slightly larger. Most typical sense organs are well developed with certain exceptions, most notably the snake 's lack of external ears (middle and inner ears are present).
The following are two lists of animals ordered by the size of their nervous system. The first list shows number of neurons in their entire nervous system. The second list shows the number of neurons in the structure that has been found to be representative of animal intelligence. [1]
For example, the basal ganglia (structures derived from the floor of the forebrain and making up MacLean's reptilian complex) were shown to take up a much smaller portion of the forebrains of reptiles and birds (together called sauropsids) than previously supposed, and to exist in amphibians and fish as well as mammals and sauropsids. Because ...
Marine vertebrates also have a far more centralized nervous system than marine invertebrates, with most of the higher functions cephalized and monopolized by the brain; and most of them have evolved myelinated central and peripheral nerve system, which increases conduction speeds significantly.
Cephalization in vertebrates, the group that includes mammals, birds, reptiles, amphibians and fishes, has been studied extensively. [4] The heads of vertebrates are complex structures, with distinct sense organs for sight, olfaction, and hearing, and a large, multi-lobed brain protected by a skull of bone or cartilage.
The enteric nervous system functions to control the gastrointestinal system. Nerves that exit from the brain are called cranial nerves while those exiting from the spinal cord are called spinal nerves. The nervous system consists of nervous tissue which, at a cellular level, is defined by the presence of a special type of cell, called the ...
Brains of an emu, a kiwi, a barn owl, and a pigeon, with visual processing areas labelled. The avian brain is the central organ of the nervous system in birds. Birds possess large, complex brains, which process, integrate, and coordinate information received from the environment and make decisions on how to respond with the rest of the body.
The cardiovascular system of snakes is unique for the presence of a renal portal system in which the blood from the snake's tail passes through the kidneys before returning to the heart. [79] The circulatory system of a snake is basically like those of any other vertebrae. However, snakes do not regulate internally the temperature of their blood.