List of animals by number of neurons


The following are two lists of animals ordered by the size of their nervous system. The first list shows number of neurons in their entire nervous system, indicating their overall neural complexity. The second list shows the number of neurons in the structure that has been found to be representative of animal intelligence.
The human brain contains 86 billion neurons, with 16 billion neurons in the cerebral cortex.

Overview

s 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, and all numbers for synapses are estimations.
NameNeurons in the brain/whole nervous systemSynapsesDetailsImageSource
Sponge0
Trichoplax0Despite no nervous system, it exhibits coordinated feeding and response behaviors.
Asplanchna brightwellii Brain only
Ciona intestinalis larva 2318617
Caenorhabditis elegans 302is the only organism to have its whole connectome completed.
Jellyfish5600Hydra vulgaris
Megaphragma mymaripenne
Box jellyfish8700–17500adult Tripedalia cystophora – does not include 1000 neurons in each of the four rhopalia
Medicinal leech
Pond snail
Sea slug18000
Amphioxus20000central nervous system only
Larval zebrafish100000
Lobster100000
Fruit fly250000In 2020 a research group announced the most sophisticated connectome
Ant250000Varies per species
Honey bee960000
Cockroach1000000
Guppy4300000
Adult zebrafishcells
Frog16000000
Naked mole-rat26880000
Little free-tailed bat35,000,000
Smoky shrew36000000
Short-tailed shrew52000000
Common bent-wing bat56,000,000
African sheath-tailed bat59,000,000
Hottentot golden mole65000000
Woermann's bat66,000,000
Zenker's fruit bat66,000,000
Commerson's roundleaf bat67,000,000
Rufous trident bat70,000,000
House mouse71000000
Nile crocodile80500000
Heart-nosed bat81,000,000
Golden hamster90000000
Short-palated fruit bat99,000,000
Ansell's mole-rat
Mashona mole-rat
Hairy-tailed mole124000000
Eastern rock elephant shrew129000000
Star-nosed mole131000000
Zebra finch131000000Brain only
Silvery mole-rat
Four-toed elephant shrew157000000
Eurasian blackcap157000000
Wahlberg's epauletted fruit bat162,000,000
Goldcrest164000000
Cape mole-rat
Egyptian fruit bat172,000,000
Mechow's mole-rat
Damaraland mole-rat
Franquet's epauletted fruit bat186,000,000
Brown rat200000000
Guyenne spiny rat202000000
Eastern mole204000000
Red junglefowl221000000
Great tit226000000
Green-rumped parrotlet227000000
Guinea pig
Gray mouse lemur
Common treeshrew261000000
Hammer-headed bat275,000,000
Pigeon310000000Brain only
Budgerigar
Cape dune mole-rat
Common blackbird
Ferret
Cockatiel
Gray squirrel
Banded mongoose
Prairie dog
Common starling
European rabbit
Octopus500000000
Western tree hyrax
Common marmoset
Eastern rosella
Barn owl
Monk parakeet
Azure-winged magpie
Rock hyrax
Cat760000000
Black-rumped agouti857000000
Magpie
Common hill myna
Northern greater galago
Western jackdaw
Eurasian jay
Alexandrine parakeet
Tanimbar corella
Emu
Three-striped night monkey
Rook
Grey parrot
Capybara1600000000
Sulphur-crested cockatoo
Raccoon
Kea
Raven2171000000Brain only
Domestic pig
Dog
Springbok
Blesbok
Blue-and-yellow macaw3136000000Brain only
Common squirrel monkey
Crab-eating macaque
Tufted capuchin
Bonnet macaque
Striped hyena
Lion
Greater kudu
Rhesus macaque
Brown bear
Giraffe
Yellow baboon
Chimpanzee28000000000
Orangutan32600000000
Gorilla33400000000
Human86000000000Neurons for average adult
African elephant257000000000

Sensory-associative structure

The cerebral cortex is a structure of particular interest at the intersection between comparative neuroanatomy and comparative cognitive psychology. Historically, it had been assumed that since only mammals have a cerebral cortex, only they benefit from the information processing functions associated with it, notably awareness and thought. It is now known that non-avian reptiles also have a cerebral cortex and that birds have a functional equivalent called the dorsal ventricular ridge, which in fact appears to be a modification subsequent to the reptilian cortex. A modern understanding of comparative neuroanatomy now suggests that for all vertebrates, the pallium roughly corresponds to this general sensory-associative structure. It is also a widely accepted view that arthropods and closely related worms have an equivalent structure, the corpora pedunculata, more commonly known as mushroom bodies. In fact this structure in invertebrates and the pallium in vertebrates may have a common evolutionary origin from a common ancestor.
Given the apparent function of the sensory-associative structure, it has been suggested that the total number of neurons in the pallium or its equivalents may be the best predictor of intelligence when comparing species, being more representative than total brain mass or volume, brain-to-body mass ratio, or encephalization quotient. It may thus be reasonably assumed that the total number of neurons in an animal's corresponding sensory-associative structure strongly relates to its degree of awareness, breadth and variety of subjective experiences, and intelligence.
Methods
The methods used to arrive at the numbers in this list include neuron count by isotropic fractionator, optical fractionator or estimation based on correlations observed between number of cortical neurons and brain mass within closely related taxa. Isotropic fractionation is often considered more straightforward and reliable than optical fractionation which may yield both overestimates and underestimates. Estimation based on brain mass and taxon is to be considered the least reliable method.
Common nameAverage number of neuronsInstraspecific variationMethodSensory-associative structureBinomial nomenclatureImageSource
Common fruit fly2,500*Optical fractionatorCorpora pedunculataDrosophila melanogaster
House cricket50,000*Optical fractionatorCorpora pedunculataAcheta domesticus
Honey bee170,000*Optical fractionatorCorpora pedunculataGenus: Apis
Common cockroach200,000*Optical fractionatorCorpora pedunculataGenus: Periplaneta
African sheath-tailed bat5,000,000Isotropic fractionatorPallium Coleura afra
Rufous trident bat6,000,000Isotropic fractionatorPallium Triaenops persicus
Naked mole-rat6,000,000± 1,065,587Isotropic fractionatorPallium Heterocephalus glaber
Little free-tailed bat6,000,000Isotropic fractionatorPallium Chaerephon pumilus
Common bent-wing bat6,000,000Isotropic fractionatorPallium Miniopterus schreibersii
Commerson's roundleaf bat8,000,000Isotropic fractionatorPallium Hipposideros commersoni
Heart-nosed bat10,000,000Isotropic fractionatorPallium Cardioderma cor
Ansell's mole-rat10,000,000Isotropic fractionatorPallium Fukomys anselli
Smoky shrew10,000,000± 352,000Isotropic fractionatorPallium Sorex fumeus
Short-palated fruit bat10,000,000Isotropic fractionatorPallium Casinycteris argynnis
Mashona mole-rat12,000,000Isotropic fractionatorPallium Fukomys darlingi
Woermann's bat12,000,000Isotropic fractionatorPallium Megaloglossus woermanni
Northern short-tailed shrew12,000,000± 1,569,000Isotropic fractionatorPallium Blarina brevicauda
Zenker's fruit bat13,000,000Isotropic fractionatorPallium Scotonycteris zenkeri
House mouse14,000,000± 2,242,257Isotropic fractionatorPallium Mus musculus
Hairy-tailed mole16,000,000± 2,611,000Isotropic fractionatorPallium Parascalops breweri
Star-nosed mole17,000,000± 3,105,000Isotropic fractionatorPallium Condylura cristata
Golden hamster17,000,000± 3,619,934Isotropic fractionatorPallium Mesocricetus auratus
Damaraland mole-rat21,000,000Isotropic fractionatorPallium Fukomys damarensis
Hottentot golden mole22,000,000± 2,154,000Isotropic fractionatorPallium Amblysomus hottentotus
Gray mouse lemur22,310,000Isotropic fractionatorPallium Microcebus murinus
Mechow's mole-rat23,000,000Isotropic fractionatorPallium Fukomys mechowii
Franquet's epauletted fruit bat23,000,000Isotropic fractionatorPallium Epomops franqueti
Hammer-headed bat24,000,000Isotropic fractionatorPallium Hypsignathus mostrosus
Hedgehog24,000,000^EstimatedPallium Subfamily Erinaceinae, various species
Silvery mole-rat25,000,000Isotropic fractionatorPallium Heliophobius argenteocinereus
Wahlberg's epauletted fruit bat26,000,000Isotropic fractionatorPallium Epomophorus wahlbergi
Cape mole-rat26,000,000Isotropic fractionatorPallium Georychus capensis
Guyenne spiny rat26,000,000± 2,155,723Isotropic fractionatorPallium Proechimys cayennensis
Eastern rock elephant shrew26,000,000± 4,020,000Isotropic fractionatorPallium Elephantulus myurus
Eastern mole27,000,000± 5,113,000Isotropic fractionatorPallium Scalopus aquaticus
Opossum27,000,000^EstimatedPallium Didelphis virginiana
Egyptian fruit bat29,000,000Isotropic fractionatorPallium Rousettus aegyptiacus
Brown Rat31,000,000+ 3,034,654Isotropic fractionatorPallium Rattus norvegicus
Four-toed elephant shrew34,000,000± 5,840,000Isotropic fractionatorPallium Petrodromus tetradactylus
Ferret38,950,000Isotropic fractionatorPallium Mustela putorius furo
Cape dune mole-rat43,000,000Isotropic fractionatorPallium Bathyergus suillus
Guinea pig43,510,000± 3,169,924Isotropic fractionatorPallium Cavia porcellus
Eurasian blackcap52,000,000Isotropic fractionatorPallium Sylvia atricapilla
Prairie dog53,770,000± 6,044,322Isotropic fractionatorPallium Genus:Cynomys
Zebra finch55,000,000Isotropic fractionatorPallium Taeniopygia guttata
Common treeshrew60,000,000± 26,510,000Isotropic fractionatorPallium Tupaia glis
Red junglefowl61,000,000Isotropic fractionatorPallium Gallus gallus
Goldcrest64,000,000Isotropic fractionatorPallium Regulus regulus
European rabbit71,450,000Isotropic fractionatorPallium Oryctolagus cuniculus
Rock dove72,000,000Isotropic fractionatorPallium Columba livia
Eastern gray squirrel77,330,000± 2,634,444Isotropic fractionatorPallium Sciurius carolinensis
Great tit83,000,000Isotropic fractionatorPallium Parus major
Western tree hyrax99,000,000Isotropic fractionatorPallium Dendrohyrax dorsalis
Green-rumped parrotlet103,000,000Isotropic fractionatorPallium Forpus passerinus
Black-rumped agouti113,000,000± 2,576,768Isotropic fractionatorPallium Dasyprocta prymnolopha
Banded mongoose115,770,000Isotropic fractionatorPallium Mungos mungo
Common blackbird136,000,000Isotropic fractionatorPallium Turdus merula
Budgerigar149,000,000Isotropic fractionatorPallium Melopsittacus undulatus
Rock hyrax198,000,000± 29,082,000Isotropic fractionatorPallium Procavia capensis
Northern greater galago226,000,000± 87,570,000Isotropic fractionatorPallium Otolemur garnettii
Common starling226,000,000Isotropic fractionatorPallium Sturnus vulgaris
Common marmoset245,000,000± 81,180,000Isotropic fractionatorPallium Callithrix jacchus
House cat249,830,000Isotropic fractionatorPallium Felis catus or Felis silvestris catus
Brown bear250,970,000Isotropic fractionatorPallium Ursus arctos
Cockatiel258,000,000Isotropic fractionatorPallium Nymphicus hollandicus
Capybara306,500,000± 62,726,120Isotropic fractionatorPallium Hydrochoerus hydrochaeris
Tarsius310,000,000EstimatedPallium Genus: Tarsius, unknown species
Eastern rosella333,000,000Isotropic fractionatorPallium Platycercus eximius
Goeldi's marmoset357,130,000Isotropic fractionatorPallium Callimico goeldii
Western grey kangaroo370,170,000Isotropic fractionatorPallium Macropus fuliginosus
Monk parakeet396,000,000Isotropic fractionatorPallium Myiopsitta monachus
Springbok396,900,000Isotropic fractionatorPallium Antidorcas marsupialis
Azure-winged magpie400,000,000Isotropic fractionatorPallium Cyanopica cyanus
Common hill myna410,000,000Isotropic fractionatorPallium Gracula religiosa
Domesticated pig425,000,000*Optical fractionatorPallium Sus scrofa domesticus
Barn owl437,000,000Isotropic fractionatorPallium Tyto alba
Emu439,000,000Isotropic fractionatorPallium Dromaius novaehollandiae
Three-striped night monkey442,000,000± 111,310,000Isotropic fractionatorPallium Aotus trivirgatus
Eurasian magpie443,000,000Isotropic fractionatorPallium Pica pica
Raccoon453,000,000Isotropic fractionatorPallium Procyon lotor
Dog 484,000,000^EstimatedPallium Canis lupus familiaris
Western jackdaw492,000,000Isotropic fractionatorPallium Coloeus monedula
Striped hyena495,280,000Isotropic fractionatorPallium Hyaena hyaena
Eurasian jay529,000,000Isotropic fractionatorPallium Garrulus glandarius
Lion545,240,000Isotropic fractionatorPallium Panthera leo
Blesbok570,670,000Isotropic fractionatorPallium Damaliscus pygargus phillipsi
Alexandrine parakeet575,000,000Isotropic fractionatorPallium Psittacula eupatria
Tanimbar corella599,000,000Isotropic fractionatorPallium Cacatua goffiniana
Dog 627,000,000Isotropic fractionatorPallium Canis lupus familiaris
Gracile capuchin monkey650,000,000^EstimatedPallium Genus: Cebus
Greater kudu762,570,000Isotropic fractionatorPallium Tragelaphus strepsiceros
Crab-eating macaque800,960,000Isotropic fractionatorPallium Macaca fascicularis
Rook820,000,000Isotropic fractionatorPallium Corvus frugilegus
Grey parrot850,000,000Isotropic fractionatorPallium Psittacus erithacus
Sulphur-crested cockatoo1,135,000,000Isotropic fractionatorPallium Cacatua galerita
Tufted capuchin1,140,000,000Isotropic fractionatorPallium Sapajus apella
Harp seal1,168,000,000^
6,100,000,000*		Estimated
Optical fractionator		Pallium Pagophilus groenlandicus
Horse1,200,000,000*Optical fractionatorPallium Equus ferus caballus
Raven1,204,000,000Isotropic fractionatorPallium Corvus corax
Kea1,281,000,000Isotropic fractionatorPallium Nestor notabilis
Common squirrel monkey1,340,000,000± 20,000,000Isotropic fractionatorPallium Saimiri sciureus
Bonnet macaque1,660,000,000Isotropic fractionatorPallium Macaca radiata
Rhesus macaque1,710,000,000Isotropic fractionatorPallium Macaca mulatta
Giraffe1,731,000,000Isotropic fractionatorPallium Giraffa camelopardalis
Blue and yellow macaw1,900,000,000Isotropic fractionatorPallium Ara ararauna
Pygmy sperm whale2,020,000,000*Optical fractionatorPallium Kogia breviceps
Leopard seal2,386,000,000^EstimatedPallium Hydrurga leptonyx
Guenon2,500,000,000^EstimatedPallium Genus: Cercopithecus, unknown species
Pigtail Macaque2,531,000,000^EstimatedPallium Macaca nemestrina
Red-and-green macaw2,646,000,000^EstimatedPallium Ara chloropterus
Harbor porpoise2,750,000,000*Optical fractionatorPallium Phocoena phocoena
Yellow baboon2,880,000,000Isotropic fractionatorPallium Papio cynocephalus
Hyacinth macaw2,944,000,000^EstimatedPallium Anodorhynchus hyacinthinus
Hamadryas baboon2,990,000,000^EstimatedPallium Papio hamadryas
Mandrill3,102,000,000^EstimatedPallium Mandrillus sphinx
Walrus3,929,000,000^EstimatedPallium Odobenus rosmarus
Southern elephant seal3,994,000,000^EstimatedPallium Mirounga leonina
African elephant5,600,000,000Isotropic fractionatorPallium Loxodonta africana
Short-beaked common dolphin6,700,000,000*Optical fractionatorPallium Delphinus delphis
Asian elephant6,775,000,000^EstimatedPallium Elephas maximus
Pygmy chimpanzee or bonobo7,250,000,000^EstimatedPallium Pan paniscus
Chimpanzee7,400,000,000*Optical fractionatorPallium Pan troglodytes
Orangutan7,704,000,000^ - 8,900,000,000^EstimatedPallium Genus: Pongo
Western gorilla9,100,000,000^EstimatedPallium Gorilla gorilla
Cuvier's beaked whale9,100,000,000*Optical fractionatorPallium Ziphius cavirostris
Beluga whale10,000,000,000^EstimatedPallium Delphinapterus leucas
Bottlenose dolphin12,700,000,000*Optical fractionatorPallium Tursiops truncatus
Common minke whale12,800,000,000*Optical fractionatorPallium Balaenoptera acutorostrata
Fin whale15,000,000,000*Optical fractionatorPallium Balaenoptera physalus
Blue whale15,000,000,000^EstimatedPallium Balaenoptera musculus
Human16,340,000,000
21,000,000,000*		± 2,170,000,000Isotropic fractionator
Optical fractionator		Pallium Homo sapiens
Risso's dolphin18,750,000,000^EstimatedPallium Grampus griseus
Short-finned pilot whale35,000,000,000^EstimatedPallium Globicephala macrorhynchus
Long-finned pilot whale37,200,000,000*Optical fractionatorPallium Globicephala melas
Killer whale43,100,000,000*Optical fractionatorPallium Orcinus orca