List of animals by number of neurons

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.

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

This list is incomplete; you can help by expanding it.

Name	Neurons in the brain/whole nervous system	Details	Image	Source
Sponge	0
Trichoplax	0
Caenorhabditis elegans (roundworm)	302	~ 7,500 synapses
Jellyfish	5,600	Hydra vulgaris (H. attenuate)
Box jellyfish	8,700-17,500	adult Tripedalia cystophora (8 mm diameter) - does not include 1000 neurons in each of the four rhopalia
Medicinal leech	10,000
Pond snail	11,000
Sea slug	18,000
Amphioxus	20,000	central nervous system only
Fruit fly	250,000
Larval zebrafish	100,000
Lobster	100,000
Ant	250,000	Varies per species
Honey bee	960,000	~ 109 synapses
Cockroach	1,000,000
Adult zebrafish	approx. 10,000,000 cells (neurons + other)		100x100px
Frog	16,000,000
Smoky shrew	36,000,000		100x100px
Short-tailed shrew	52,000,000
House mouse	71,000,000	~ 1011 synapses
Golden hamster	90,000,000
Star-nosed mole	131,000,000		100x100px
Brown rat	200,000,000	4.48 × 1011
Eastern mole	204,000,000
Guinea pig	240,000,000
Common treeshrew	261,000,000
Octopus	500,000,000
Common marmoset	636,000,000
Cat	760,000,000	~ 1013 synapses
Black-rumped agouti	857,000,000
Northern greater galago	936,000,000
Three-striped night monkey	1.468×10^9
Capybara	1.6×10^9
Common squirrel monkey	3.246×10^9
Tufted capuchin	3.691×10^9
Rhesus macaque	6.376×10^9
Human	8.6×10^10	For average adult; 1014–1015 synapses
African elephant	2.67×10^11

Cerebral cortex

Only mammals appear in this list, because only mammals have a cerebral cortex (although the pallium of reptiles and birds is also frequently referred to as "cortex".)

Name	Neurons in the cerebral cortex	Details	Image	Source
Mouse	4,000,000	Genus Mus, musculus
Rat	15,000,000 21,000,000	Genus Rattus, unknown species
Hedgehog	24,000,000	Subfamily Erinaceinae, unknown genus and species
Opossum	27,000,000	Family Didelphidae, unknown genus and species
Dog	160,000,000	Canis lupus familiaris
Cat	300,000,000	Felis catus or Felis silvestris catus
Tarsius	310,000,000	Genus Tarsius, unknown species
Squirrel monkey	430,000,000	Genus Saimiri, unknown species
Domesticated pig	450,000,000	Sus scrofa
Raccoon	453,000,000
Rhesus macaque	480,000,000	Macaca mulatta
Gracile capuchin monkey	600,000,000–700,000,000	Genus Cebus, unknown species
Horse	1.2×10^9	Equus ferus caballus
Guenon	2.5×10^9	Genus Cercopithecus, unknown species
Gorilla	4.3×10^9	Genus Gorilla, unknown species	100px
Chimpanzee	6.2×10^9	Genus Pan, unknown species
False killer whale	1.05×10^10	Pseudorca crassidens
African elephant	1.1×10^10	Genus Loxodonta, unknown species
Fin whale	1.5×10^10	Balaenoptera physalus
Human	1.9×10^10–23,000,000,000	For average adult "The average number of neocortical neurons was 19 billion in female brains and 23 billion in male brains."
Long-finned pilot whale	3.72×10^10	Globicephala melas: "For the first time, we show that a species of dolphin has more neocortical neurons than any mammal studied to date including humans."	100px

See also

• Lists of animals
• Brain size
• Brain-to-body mass ratio

• Connectome
• Connectomics
• Cranial capacity