An embarrassing artefact of the Google algorithm is that ridiculous claims make the top page based on popularity, not accuracy.
A quick search for ‘the smallest animal in the world‘ throws up a tiny mammal that, though small for a furry, warn-blooded creature, is still larger than the vast majority of animals on earth.
Luckily, we’re here to set things straight.
The vast majority of animals are arthropods. This is true both in terms of the number of species and sheer biomass.
Insects make up the majority of this phylum, and the majority of those are smaller than the smallest mammal.
So, in the ultimate rankings, the Etruscan shrew, shamelessly paraded as the smallest animal, is actually much closer in size ranking to the African elephant than the smallest animals on the planet.
This sort of biogeek pedantry is what we live for, so we’ve put together a series of three lists:
Since the true smallest animals would all be relatively similar, and we want to spare you a list of 30 microscopic nematodes with names like Caenorhabditis Elegans, we’ve divided them into categories and picked the smallest of each instead.
The Smallest Animals On Land (by Type)
1. Smallest Mammal – Etruscan Shrew (40 mm)
The smallest mammal is up for grabs and comes down to a tie between the hognosed bat and this little guy, the Etruscan shrew.
Since the bat wins the trophy for the smallest mammal in the air, the shrew gets this one.
The Etruscan shrew weighs only 1.8 g and is the smallest mammal by mass. At 40mm long, you’d be lucky to find a shorter mammal on the ground, too.
They’re widely distributed across Southern Europe, The Middle East, North Africa and into Asia, and spend all their time either eating, grooming, or sleeping. 3
2. Smallest Insect – Dicopomorpha echmepterygis (0.14 mm)
The smallest insect is a wasp in the same family as the smallest flying animal.
This one is a male of a different species and doesn’t have wings, but it has been found significantly smaller than its flying cousins.
This wasp is so small that it’s shorter than some amoebas and bacteria. They don’t do much other than occupy the egg of their host as a parasite and mate with the much larger females of the species. 4
3. Smallest Elephant – Palaeoloxodon falconeri (1 m tall)
We’re making an exception for one extinct animal that’s a perfect illustration of island insular dwarfism.
A descendant of the gargantuan, four-meter-tall P. antiquus, this tiny elephant got trapped on an island in Italy and began shrinking.
At around 1 meter tall, these were the smallest elephants we know to have existed anywhere, and could possibly have made good pets.
4. Smallest Primate – Madame Berthe’s Mouse Lemur (92 mm)
This 30g lemur is yet another island example of a tiny animal. It averages under 10cm long and makes up one of the many lemur species in Madagascar.
Berthae is just one of a whole bunch of mouse lemurs on the island, and one that, like many others, is critically endangered.
The increase in slash-and-burn agriculture has devastated its forest habitat and numbers are still decreasing. 5
5. Smallest Scorpion – Microtityus minimus (11.4 mm)
This species was discovered as recently as 2014, so there’s not a lot of information about it yet, other than it is very small.
Just over a centimetre in length, this little stinger must be good at finding even tinier animals to eat.
They’re found on the Southern foothills of the Cordillera Central Mountains in the Dominican Republic, but their distribution has yet to be established.
6. Smallest Lizard – Jaragua Dwarf Gecko (16 mm)
The Jaragua dwarf lizard, discovered on an island off the coast of the Dominican Republic, is the smallest known reptile.
Adults are just 1.6cm long, and there may be smaller ones to discover. Surprisingly, for a tiny animal on an island inhabited by people, these lizards seem to be doing okay and have everything they need for a stable population, despite increased deforestation in the area.
This is a good example of island miniaturization, in which isolated communities of animals evolve to get smaller and smaller as a response to fewer resources.
7. Smallest Frog – Paedophryne amauensis (7.7 mm)
The world’s smallest frog is a species from Papua New Guinea and is considered the smallest vertebrate.
It’s significantly less than a centimetre in length at 7.7mm from nose to tail, and though marginally shorter than the smallest fish, it’s also heavier, making the distinction between them negligible.
They live well above sea level, at 150-800 meters up in wet forest habitats.
8. Smallest Spider – Patu digua (0.37 mm)
This male spider was found alongside a slightly larger female of a different species.
As females are usually significantly larger, it’s proposed that the male of the species Anapistula caecula would likely be even smaller than this little guy, but until then, he holds the record.
The males of this species reach around 0.37mm long and are found in Colombia. They’re a type of dwarf orb-weaver, similar to the common garden spiders, but very, very tiny!
9. Smallest Collembola – Springtail (0.2 mm)
Springtails can be found all over the world, under almost every stone or log, and yet very few are ever seen. This is because they’re so small!
Most of the largest springtails are just a millimetre or two long, and the smallest is almost impossible to spot.
They’re closely related to insects, but make up their own order, Collembola, and the shortest one we could find is 0.2mm long.
They’re also very important decomposers, occupying the top layers of soil and recycling nutrients from the leaf litter
10. Smallest worm – Protorhabditis hortulana (0.2 mm)
80% of all individual animals are nematodes. Their abundance is greater than any other lifeform and they live in all habitats and occupy innumerable niches.
So it’s likely that the smallest animal on earth is a nematode, and this species is a good place to start.
Discovered in a compost pile near the Iberian peninsula, it represents one of the countless nematode species in this size bracket and one of the smallest animals on earth at under 0.2mm long.
11. Smallest Mites – Demodex brevis (0.1 – 0.2 mm)
Mites can be some of the most useful and most devastating animals. Some provide fantastic ecosystem services, while others spread terrible diseases.
One that causes a lot of damage to crops is the tomato russet mite, a very small example at 0.2mm.
To put this in perspective, these mites are around the size of Demodex brevis, those mites found at the base of your eyelids, feeding on your sebaceous juices, that you might not have known about until now…
The Smallest Animals In The Air (by Type)
Insects are the only flying arthropods, meaning there will be no spiders, ticks, mites, or scorpions on this list, and that’s a shame. Check out the smallest land animals list for some of these, though!
Still, there are quite a few interesting birds and even bats to consider, and a diverse range of flying insects to get into. Let’s take a look!
1. Smallest Bird – Bee hummingbird (6 cm)
Flying birds are notoriously lightweight for their size, but this bee hummingbird takes it to the extreme.
At just over 2g and around 6cm long, this is the smallest bird known and it lives only in Cuba.
As a flower feeder, it pollinated plants as it moves from flower to flower, maintaining a daily routine of over a thousand flowers to meet its energy needs. 6
2. Smallest Raptor Bird – Black-thighed falconet (15 cm)
This tiny raptor pushes the boundary of miniaturisation in predatory birds.
It’s barely bigger than a sparrow itself, at around 15cm tall, and since most other birds are bigger than it is, it also chases down insects and lizards.
Still, this is a powerful little falcon that can tackle prey as large as itself, and weighing as little as 35g, it’s an impressive, tiny bird hunter.
3. Smallest Bat – Kitti’s hog-nosed bat (2.5 cm)
This is a top contender for the smallest mammal, which would make the top Google result for “smallest animal” doubly inaccurate!
These tiny, hog-nosed bats occupy caves and get out to feed in short crepuscular trips before the bigger animals notice they’re around.
These bats are only known to exist in a single Burmese province and a small patch of Thailand, and while their true distribution is unknown, they’re currently considered Near Threatened.
Also known as the bumblebee bat, it weighs about 2 grams and is slightly heavier, but smaller in length than the Etruscan shrew at around 2.5cm. 7
4. Smallest Butterfly – Sinai baton blue (14 – 18 mm)
As we get rid of the cumbersome bones and spinal columns of the smallest vertebrates, we start to see a rapid decrease in size.
The smallest butterfly known is Sinai baton blue, and its tiny wingspan of just 14-18 mm makes it one of the cutest, too.
This butterfly has been studied in conjunction with global warming and habitat fragmentation research and is currently listed as critically endangered by the IUCN due to both of these factors.
5. Smallest Moth – Stigmella maya (2.8 mm)
But the Siniai baton blue isn’t the smallest Lepidopteran, that title goes to a Mexican species known only as Stigmella maya.
This exceptionally small moth can be as tiny as 2.8mm in wingspan and is just one of a vast genus of hundreds of tiny moths.
Its larvae are small enough to burrow between layers in the leaves of their host plants.
6. Smallest Bee – Perdita minima (2 mm)
Since almost everything small seems to be named after a bee, let’s see how small a bee can get!
Bees are a lot more diverse than people realise. There are an estimated 20,000 species of bee, and thousands can be found in most non-frozen countries.
The smallest bee recorded so far is found in Texas, and is much smaller than the eye of some of the largest species of bee.
Perdita minima is a pollinator, and grows to around 2mm long. While it’s the smallest bee known, it’s unlikely to be the smallest out there, as thousands of species remain undiscovered and the vast majority of the African continent is under-studied.
7. Smallest Dragonfly – Scarlet dwarf (20 mm)
This tiny predator is known as the Scarlet Dwarf. Not a very intimidating name, but don’t be fooled; like all dragonflies, the smallest on record is an aerial acrobat, able to fly backwards, change direction in the blink of an eye, and hit some of the fastest speeds of any flying insect.
This one hits an upper limit of about 20mm across and is commonly found patrolling abandoned paddy fields in Asia.
While this species is doing well globally, local populations are endangered due to habitat fragmentation.
8. Smallest Fly – Euryplatea nanaknihali (0.4 mm)
Now we’re getting to one of the smallest insects, and the smallest true fly at 0.4mm in length!
This is a parasite of ants and is thought to lay its eggs inside their heads. Being so tiny, there’s still quite a lot to understand about this animal, but the family is well-recognized by science.
Phoridae flies were already thought to be one of the most diverse families of insects, as well as having the widest range of sizes of any insect family.
As parasites, they have a significant effect on the population dynamics of their hosts and this relatively new discovery opens up more questions about the smallest possible insects. 8
9. Smallest Beetle – Scydosella musawasensis (0.3 mm)
A Colombian featherwing beetle has set the record for the smallest beetle amid the most diverse order of animals on the planet. Around a quarter of all animal species are beetles, and they’re almost half of all insects, so there’s a lot of competition!
This tiny beetle is 0.3mm long, and it’s not only the smallest beetle, but it’s also the smallest free-living (as in, not a parasite or parasitoid) insect recorded.
10. Smallest Flying Animal – Megaphragma caribea (0.2 mm)
The smallest flying insect appears to be M. caribea from Guadaloupe, measuring around 0.2mm.
This is a type of Fairyfly, but it’s not a true fly at all. Fairyflies are actually a type of parasitic wasp and the smallest insects on record.
In many species, the males are flightless, making them unfit for this list despite being the smallest insects on record, but the winged females of this species are still small enough to compete.
These wasps are so tiny there isn’t even enough space in their neurons for a cell nucleus. They’re the subject of research into how miniaturisation works and what sacrifices an animal needs to make to become tiny. 9
The Smallest Animals In The Water (by Type)
1. Smallest Fish – Paedocypris progenetica (7.9 mm)
This may well be the smallest vertebrate known. Paedocypris fish are a type of freshwater cyprinid that occupy peat swamps and wetlands in Indonesia.
They’re listed as Near Threatened as a result of habitat degradation, as peat swamps are being routinely destroyed to make space for crops like oil palm and shrimp farms.
Paedocypris progenetica is so-named for its immature appearance, keeping qualities of its larval morphology well into sexual maturity. 10
2. Smallest Swimming Mammal – American water shrew (120mm)
This tiny water shrew is only semi-aquatic, but it deserves a mention for its tiny size and being the smallest diving mammal.
It’s found in the US and Canada, and weighs only up to 18g. The large examples can be up to 17cm, but they’re commonly as small as 12cm long.
They have special olfactory organs on their faces that allow them to smell underwater and will attack anything that wriggles.
3. Smallest Shark – Dwarf lanternshark (200 mm)
Since we’ve done the biggest sharks, it’s only fair we give a shoutout to the smallest. The lanternsharks are a small bunch, and the dwarf lanternshark is the smallest of them all.
This is a relatively-unknown species, even for sharks, but one thing that stands out is how petite it is.
It’s a 20cm dogfish, found just below the photic zone, and is currently the tiniest shark we know about. 11
4. Smallest Crab – Pea crab (15 mm)
The pea crab makes itself at home inside an edible clam, which is probably the only reason we know about it.
At best, this animal is about 1.5cm across, and only around 7mm from front to back. It’s one of a group of pea crab species that lives inside this host; the unfortunately-named fat gaper clam. 12
5. Smallest Jellyfish – Malo kingi (5 mm)
Irukandji jellyfish in the genus Malo, this one is known as the kingslayer, named after one of its victims, Robert King.
These are tiny, but deadly jellyfish unsurprisingly found off the coast of Australia. At half a centimetre, they’re almost impossible to spot, which makes researching them difficult.
Their venom is exceptionally potent and creates a physiological response so unique it’s called Irukandji after them. 13
6. Smallest Exclusively Aquatic Insect – Riffle Beetles (1 mm)
While there are plenty of invertebrates in the ocean, there aren’t really any insects that live in the marine environment – crustaceans take up most of those niches.
And in freshwater, there are very few who live exclusively in water throughout their life cycle.
Many insects have a life stage that involves living submerged, but only a small portion of these stay in the water as they mature.
Riffle beetles can spend at least 9 years without leaving the water, which qualified them as aquatic enough for this list.
Of the 5,000 species of riffle beetle, it’s impossible to be certain of the smallest, but Oulimnius tuberculatus is a good candidate.
Measured at 1mm long, it’s one of the smallest insects in the water.
7. Smallest Bivalve – Condylonucula maya (0.5 mm)
Going from the giant clam to the micromollusk, we have the smallest bivalve currently recognized.
This tiny, tiny clam is only half a millimetre long, smaller than a lot of the grains of sand it would be found in!
8. Smallest Copepod – Sphaeronellopsis monothrix (0.1 mm)
A lot is going on in the world of ocean zooplankton, and while the ‘zoo’ part of the word refers to animals and differentiates against photosynthetic algae (plants), it has come to encompass other organisms that are no longer considered animals, such as single-celled protists.
With that in mind, the smallest planktonic animals are likely to be copepods like S. monothrix, which can be as small as 0.1mm.
This parasitic plankton makes up a large portion of the food web in the ocean and lives in their own little worlds, drifting about in the ocean much like we as a planet drift about the galaxy with no control over where we’re going.
9. Smallest Worm – Ocean nematodes (0.08 mm)
Nematodes are everywhere. C. elegans from the introduction is an example of a nematode, and they’re both free-living and parasitic, as well as making up some of the largest and smallest worms in the world.
The ocean is home to both ends of this spectrum, including one 8-meter whale parasite, and while it houses the smallest too, there are several contenders for that title.
What we know is that both Desmoscolex sp. and Greeffiella sp measure in at around 0.08mm, making them one of the smallest animals in the water, and vindicating the claim that a true list of smallest animals would be infested with worms.
10. Smallest Swimming Arthropod – Tantulacus dieteri (0.08 mm)
This may be the smallest arthropod in the world. At a recorded length of 0.08mm long, this parasitic crustacean is certainly the smallest animal we can find for this list.
Like its copepod neighbour, this animal will float around uncontrollably, affixed to its host in the plankton soup that makes up the nutrient foundation of all the larger animals.
So that concludes our list of the smallest animals in the world, on land, air and sea, by type.
Let’s touch on why smaller animals are so much more successful than their larger neighbors.
The Benefits of Being Small
Most animals are small. As humans, we comprise about 100 trillion cells, and that’s just in our tissues. In our gut there can be anything from 15 trillion to 724 trillion microbes, pushing out mass up to a potential 800 trillion cells or more.
Across the animal kingdom, while size differs significantly, the cells that make up each animal stay within a similar scale (there are some pretty glaring exceptions to this rule: an ostrich egg is an example of a single animal cell that is about 15cm across).
To refer back to our friend C. elegans, which has around 2,000 cells, this means that we are hundreds of billions of times the size of the smallest, multicellular animals.
In contrast, an elephant may be no more than a hundred times our mass and the difference between a 7-ton mammoth and a 1g baby shrew is still only seven million.
So, being small is popular, and there are a lot of reasons for this.
Being small means you can reproduce faster. Cellular division doesn’t take as long with 2,000 cells as it does with hundreds of trillions, and this can be advantageous.
Next, there is real estate availability. Being tiny really opens up your options regarding where you can live.
You don’t need to eat much, as your biological processes are relatively simple, and you can spawn into the air or water in many cases.
Being big is good for some things too, but when the extinction events inevitably come, large animals are the first to perish.
Mammals that survived the extinction of the dinosaur were all tiny, and grew to enormous sizes only after niches that were previously held by their reptilian overlords became newly available.
Being isolated on islands often results in smaller animals due to the increased efficiency of having a smaller stomach.
So, the animals on this list know what they’re doing.
The Problem With Being Small
Small animals are a lot harder to come by than larger ones, making these lists prone to significant change, the closer we look.
Almost every tiny animal on these lists was discovered in the last decade or three, which goes to show how long it can take to find them!
Fact Sources & References
- Iman Ghosh (2021), “All the Biomass of Earth, in One Graphic“, Visual Capitalist.
- “Phylum Arthropoda“, Exploring Our Fluid Earth.
- “Top 10: Earth’s smallest mammals“, Science Focus.
- Edward L. Mockford (1997), “A New Species of Dicopomorpha (Hymenoptera: Mymaridae) with Diminutive, Apterous Males“, Annals of the Entomological Society of America.
- Markolf, M., Schäffler, L. & Kappeler, P (2022), “Microcebus berthae“, The IUCN Red List of Threatened Species 2022.
- Eric R. Miller, Murray E. Fowler (2015), “Fowler’s Zoo and Wild Animal Medicine, Volume 8“, Google Books.
- “Bumblebee bat (Craseonycteris thonglongyai)“, Edge of Existence.
- Ed Yong (2012), “The world’s smallest fly probably decapitates really tiny ant“, National Geographic.
- Alexey A. Polilov (2017), “First record of Megaphragma (Hymenoptera, Trichogrammatidae) in Columbia, and third animal species known to have anucleate neurons“, Journal of Hymenoptera Research 60.
- Maurice Kottelat (2005), “Paedocypris, a new genus of Southeast Asian cyprinid fish with a remarkable sexual dimorphism, comprises the world’s smallest vertebrate“, Proceedings of The Royal Society.
- “Dwarf Lantern Shark“, Smithsonian.
- Zmarzly, Deborah L (1992), “Taxonomic review of pea crabs in the genus Pinnixa (Decapoda: Brachyura: Pinnotheridae) occurring on the California shelf, with descriptions of two species“, Crustacean Biology.
- “Weird Science: Deadly Box Jellyfish“, Exploring Our Fluid Earth.