List of animals by number of neurons

Brief comparisons of number of whole brain neurons (top) and cerebral cortex neurons (bottom) among five mammals.

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 either 19 or 23 (respectively female and male) 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.

Name	Neurons in the brain/whole nervous system	Synapses	Details	Image	Source
Sponge	5000000000000000000♠0				[1]
Trichoplax	5000000000000000000♠0				[2]
Caenorhabditis elegans (roundworm)	7002302000000000000♠302	7003750000000000000♠~7,500			[3]
Jellyfish	7003560000000000000♠5,600		Hydra vulgaris (H. attenuate)		[4]
Box jellyfish	7003870000000000000♠8,700-7004175000000000000♠17,500		adult Tripedalia cystophora (8 mm diameter) - does not include 1000 neurons in each of the four rhopalia		[5]
Medicinal leech	7004100000000000000♠10,000				[6]
Pond snail	7004110000000000000♠11,000				[7]
Sea slug	7004180000000000000♠18,000				[8]
Amphioxus	7004200000000000000♠20,000		central nervous system only		[9] [10]
Fruit fly	7005250000000000000♠250,000	7007100000000000000♠<1×10^7			[11] [12]
Larval zebrafish	7005100000000000000♠100,000				[13]
Lobster	7005100000000000000♠100,000				[14]
Ant	7005250000000000000♠250,000		Varies per species		[15] [16]
Honey bee	7005960000000000000♠960,000	7009100000000000000♠~1×10^9			[17]
Cockroach	7006100000000000000♠1,000,000				[18]
Adult zebrafish	7007100000000000000♠~10,000,000		cells (neurons + other)		[19]
Frog	7007160000000000000♠16,000,000				[20]
Smoky shrew	7007360000000000000♠36,000,000				[21]
Short-tailed shrew	7007520000000000000♠52,000,000				[21]
House mouse	7007710000000000000♠71,000,000	7012100000000000000♠~1×10^12			[22]
Golden hamster	7007900000000000000♠90,000,000				[22]
Star-nosed mole	7008131000000000000♠131,000,000				[21]
Zebra finch	7008131000000000000♠131,000,000		Brain only		[23]
Brown rat	7008200000000000000♠200,000,000	7011448000000000000♠~4.48×10^11			[24]
Eastern mole	7008204000000000000♠204,000,000				[21]
Guinea pig	7008240000000000000♠240,000,000				[22]
Common treeshrew	7008261000000000000♠261,000,000				[25]
Pigeon	7008310000000000000♠310,000,000		Brain only		[23]
Octopus	7008500000000000000♠500,000,000				[26]
Common marmoset	7008636000000000000♠636,000,000				[25]
Cat	7008760000000000000♠760,000,000	7013100000000000000♠~1×10^13			[27]
Black-rumped agouti	7008857000000000000♠857,000,000				[22]
Northern greater galago	7008936000000000000♠936,000,000				[25]
Three-striped night monkey	7009146800000000000♠1,468,000,000				[25]
Capybara	7009160000000000000♠1,600,000,000				[22]
Raven	7009217100000000000♠2,171,000,000		Brain only		[23]
Common squirrel monkey	7009324600000000000♠3,246,000,000				[25]
Tufted capuchin	7009369100000000000♠3,691,000,000				[25]
Rhesus macaque	7009637600000000000♠6,376,000,000				[25]
Human	7010860000000000000♠86,000,000,000	7014150000000000000♠~1.5×10^14	Synapses for average adult		[28][29][30]
African elephant	7011257000000000000♠257,000,000,000				[31][32]

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	7006400000000000000♠4,000,000	Genus Mus, musculus		[7]
Rat	7007180000000000000♠18,000,000	Genus Rattus, unknown species		[33] [34]
Hedgehog	7007240000000000000♠24,000,000	Subfamily Erinaceinae, unknown genus and species		[33]
Opossum	7007270000000000000♠27,000,000	Family Didelphidae, unknown genus and species		[33]
Dog	7008160000000000000♠160,000,000	Canis lupus familiaris		[7]
Cat	7008300000000000000♠300,000,000	Felis catus or Felis silvestris catus		[7]
Tarsius	7008310000000000000♠310,000,000	Genus Tarsius, unknown species		[35]
Squirrel monkey	7008430000000000000♠430,000,000	Genus Saimiri, unknown species		[36]
Domesticated pig	7008425000000000000♠425,000,000	Sus scrofa		[37]
Raccoon	7008453000000000000♠453,000,000			[38]
Rhesus macaque	7008480000000000000♠480,000,000	Macaca mulatta		[33]
Gracile capuchin monkey	7008650000000000000♠650,000,000	Genus Cebus, unknown species		[36]
Horse	7009120000000000000♠1,200,000,000	Equus ferus caballus		[21]
Guenon	7009250000000000000♠2,500,000,000	Genus Cercopithecus, unknown species		[35]
Gorilla	7009430000000000000♠4,300,000,000	Genus Gorilla, unknown species		[36]
Chimpanzee	7009620000000000000♠6,200,000,000	Genus Pan, unknown species		[7]
False killer whale	7010105000000000000♠10,500,000,000	Pseudorca crassidens		[21]
African elephant	7010110000000000000♠11,000,000,000	Genus Loxodonta, unknown species		[21]
Fin whale	7010150000000000000♠15,000,000,000	Balaenoptera physalus		[39]
Human	7010210000000000000♠21,000,000,000	For average adult "The average number of neocortical neurons was 19 billion in female brains and 23 billion in male brains."		[30] [40]
Long-finned pilot whale	7010372000000000000♠37,200,000,000	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."		[41]

See also

References