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Not all animals have neurons; Trichoplax and sponges lack nerve cells altogether. Neurons may be packed to form structures such as the brain of vertebrates or the neural ganglions of insects. The number of neurons and their relative abundance in different parts of the brain is a determinant of neural function and, consequently, of behavior.
Compared to that of other mammals, the pulvinar region of the brain – which helps to visually detect relevant objects – is disproportionately large and effective in the brains of primates (including humans). The concept of snakes being a special threat to humans has been confirmed by population-based studies.
Nocturnal animals (for example, tarsiers) and animals that live in open landscapes have larger eyes. The vision of forest animals is not so sharp, and in burrowing underground species (moles, gophers, zokors), eyes are reduced to a greater extent, in some cases (marsupial moles, mole rats, blind mole), they are even covered by a skin membrane.
As in larger brains, two basic neural architectural principles of many invertebrate brains are the existence of specialized brain structures and circuits, which refer to specific sensory domains, and of higher-order integration centres, in which information pertaining to these different domains converges and is integrated, thus allowing cross ...
Brain of a human (left), compared to that of a black rhinoceros (center) and a common dolphin (right). Elephant brains also show a complexity similar to dolphin brains, and are also more convoluted than that of humans, [20] and with a cortex thicker than that of cetaceans. [21]
Thus, large whales have very small brains compared to their weight, and small rodents like mice have a relatively large brain, giving a brain-to-body mass ratio similar to humans. [4] One explanation could be that as an animal's brain gets larger, the size of the neural cells remains the same, and more nerve cells will cause the brain to ...
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Monocular vision is vision using only one eye. It is seen in two distinct categories: either a species moves its eyes independently, or a species typically uses two eyes for vision, but is unable to use one due to circumstances such as injury. [1] Monocular vision can occur in both humans and animals (such as hammerhead sharks).