ANIMAL AND HUMAN BRAINS
Human brain is one of the defining features of our species.
BRAIN SIZE:
Size of the brain indicates its total processing power. A Honey Bee’s tiny brain contains one million neurons. A Nile crocodile has 80 million neurons while a human brain has 90 billion neurons. This link with intelligence is clear. The largest brain at 17lbs belongs to sperm whale. All mammalian brains contain the same components, but they grow in different proportions. A third of the volume of a rat’s central nervous system is made up of the spinal cord, indicating its reliance on reflex movements. By contrast, the spinal cord is tenth of a human CNS. Instead, three quarters is taken by cerebrum in humans, which is used for perception and cognition.
Size of the brain indicates its total processing power. A Honey Bee’s tiny brain contains one million neurons. A Nile crocodile has 80 million neurons while a human brain has 90 billion neurons. This link with intelligence is clear. The largest brain at 17lbs belongs to sperm whale. All mammalian brains contain the same components, but they grow in different proportions. A third of the volume of a rat’s central nervous system is made up of the spinal cord, indicating its reliance on reflex movements. By contrast, the spinal cord is tenth of a human CNS. Instead, three quarters is taken by cerebrum in humans, which is used for perception and cognition.
BRAIN SHAPE:
Sponges have no nerve cells at all. While Jelly fish and corals have a net like nervous system but no central point. The brains of all vertebrates follow the same development plan. Variety is seen in invertebrates. Leech’s nervous system is arranged in chains of cell clusters called ganglion. There are around 1000 cells in its nervous system. In comparison an octopus brain contains 500 million neurons, only a third are located in the head and the rest are in the arms and skin where they control sensory and motor functions. Shark brain is Y shaped due to the large olfactory bulbs. This sense of smell is its primary means of tracking prey. The hearing and vision centers in dolphin brain are larger and closer together to help it create a mental image using its sonar.
Sponges have no nerve cells at all. While Jelly fish and corals have a net like nervous system but no central point. The brains of all vertebrates follow the same development plan. Variety is seen in invertebrates. Leech’s nervous system is arranged in chains of cell clusters called ganglion. There are around 1000 cells in its nervous system. In comparison an octopus brain contains 500 million neurons, only a third are located in the head and the rest are in the arms and skin where they control sensory and motor functions. Shark brain is Y shaped due to the large olfactory bulbs. This sense of smell is its primary means of tracking prey. The hearing and vision centers in dolphin brain are larger and closer together to help it create a mental image using its sonar.
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