This is a list of representative animals by the number of neurons in their whole nervous system and the number of neurons in their brain (for those with a brain). These numbers are estimates derived by multiplying the density of neurons in a particular animal by the average volume of the animal's brain.
The whole human brain contains 86 billion neurons and roughly 16 billion neurons in the cerebral cortex.
Overview
Neurons are the cells that transmit information in an animal's nervous system so that it can sense stimuli from its environment and behave accordingly. 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.
Whole nervous system
All numbers for neurons but Caenorhabditis and all numbers for synapses are estimations.
Cerebral cortex
Non-mammals are included in this list because, although only mammals have a cerebral cortex, the pallium of reptiles and birds is functionally similar to the mammalian cortex and is therefore also frequently referred to as "cortex".
See also
References
