Who is the tiniest of them all? Get to know the incredibly small creatures of the world.
In the 1800s, Christian Bergmann, a zoologist from Germany, contemplated a basic inquiry: what causes some animals to be smaller in size? He determined that the size of warm-blooded animals is directly related to the temperature of their environment, and this concept still holds true in the field of biology today.
According to Dr. Simon Loader, principal curator of vertebrates at the Natural History Museum, Bergmann’s observation states that smaller species typically inhabit warmer regions. This trend is related to their surface area and volume, as smaller animals lose heat more quickly and may struggle to regulate their body temperature in colder environments. Regardless of the explanations, these smaller species are intriguing.
As our understanding of life on Earth continues to expand, scientists are constantly uncovering new, minuscule organisms each year. This is causing a shift in the definition of what is considered the smallest of their species, leading to heated debates over who truly holds the title of the tiniest organism.
Smaller organisms can often be overlooked or ignored when it comes to conservation efforts, compared to more well-known and charismatic species. According to Paul Rees, a nursery manager at Kew Gardens, this is a common occurrence. We spoke to scientists to learn about the tiniest creatures in their respective fields.
The tiniest reptile in the world is the Brookesia nana nano-chameleon, found in Madagascar.
The discovery of a male Brookesia nana in 2021 revealed that this species, measuring only 20mm (0.8in) in length, can be found in the rainforests of northern Madagascar. Female specimens are slightly larger, growing up to 30mm. Sadly, due to deforestation, this tiny reptile is considered critically endangered.
Brookesia nana is noteworthy for its unusually large male reproductive organs, referred to as hemipenes in reptiles.
Loader explains that smaller males may require bigger hemipenes in order to have a more suitable physical match with larger females.
Madagascar is well-known for its diminutive creatures, such as various tiny frogs and the Madame Berthe’s mouse lemur, which holds the title of the smallest primate in the world.
The tiniest bird is the bee hummingbird, found in Cuba.
The Mellisuga helenae, also known as the bee hummingbird, has a weight equivalent to that of a paperclip and a length of only 5-6cm (1.9-2.3in). This tiny bird is typically spotted in dense forests and at the edge of woodlands in Cuba, with its eggs being comparable in size to a coffee bean and its wings flapping 80 times per second. The destruction of its habitat on the Caribbean island has raised concerns among scientists about the species’ survival.
According to Dr. Ian Burfield, the global science coordinator for BirdLife International, the population of this species is believed to be decreasing by 20-29% every decade due to deforestation and degradation of its habitat. It has already vanished from numerous areas where it was once abundant.
According to him, similar to other hummingbirds, it consumes nectar from various types of blooming flowers and serves as a crucial pollinator, making its decrease even more worrisome.
The tiniest bug is the Dicopomorpha echmepterygis, which is a parasitic wasp found in the United States.
The smallest insect in the world is smaller than certain single-celled organisms. The US parasitic wasp, measuring only 0.139mm in length, resides inside its host, the bark louse, for the majority of its lifespan.
Dr. Gavin Broad, the lead curator of entomology at the Natural History Museum, describes these creatures as a type of wasp called “fairyflies”. They are very small and grow by parasitizing the eggs of bark lice, which are also relatively small.
According to Broad, a single female wasp grows inside the host egg and consumes the majority of its contents. This female is accompanied by one to three males who do not have wings, have underdeveloped heads, and remain inside the egg without ever leaving. Their sole purpose is to fertilize the females.
The tiniest amphibian known is the Paedophryne amauensis frog, found in Papua New Guinea.
This tiny frog is so small it does not have tadpoles. Described in 2012, the frog lives in rainforest leaf litter, feeding on ticks and mites.
According to Dr. Jeff Streicher, principal curator of herpetology at the Natural History Museum, this particular frog species has a unique life cycle that does not involve a tadpole stage in water. Instead, the eggs are laid in damp leaf litter on the floor of the forest and hatch into tiny froglets. These adult frogs survive by consuming small invertebrates also found in the leaf litter. This type of lifestyle is common among other small frog species and emphasizes the important role that leaf litter microhabitats play in the survival of these small amphibians.
The tiniest mammals are the Etruscan shrew and the bumblebee bat.
It is a challenge to distinguish between two small competitors among mammals. The Etruscan shrew, which inhabits areas in Eurasia and north Africa, typically weighs between 1.2g and 2.7g. This tiny creature is solitary and primarily active at night, feeding on invertebrates. According to Paula Jenkins, senior curator of mammals at the Natural History Museum, the shrew has a short lifespan and usually does not survive past its second winter.
The bumblebee bat, also known as the hog-nosed bat, is another small mammal that is considered the smallest in the world. It can be found in two separate areas in Thailand and Myanmar. Like the Etruscan shrew, it weighs approximately 2g and has a wingspan of up to 145mm. Its body length ranges from 29mm to 33mm.
According to Jenkins, this species of animal makes its home in large caverns found in limestone formations close to riverbanks. Each individual tends to have their own separate roosting spot at a significant distance from others. They primarily search for invertebrates in the upper layers of the forest, using echolocation to locate their prey while in flight. Additionally, they may also pluck their prey directly from the foliage.
The tiniest flowering plant is Wolffia globosa, originating in Asia but present across the globe.
Wolffia globosa, also called duckweed, is a plant that has the highest growth rate among all plants and can rapidly spread over large bodies of water. Despite not having typical plant parts like leaves, roots, and stems, it produces the tiniest fruit and is very nourishing.
According to Tom Pickering, the head manager of the display glasshouses at Kew’s Royal Botanic Gardens, the plant has a similar appearance and behavior to a weed. It is a highly resilient aquatic plant that is cultivated in tanks in the tropical nursery at Kew and has global applications in animal feed, medicine, and food. Despite its small size, Wolffia belongs to the same plant family as the titan arum, a flowering plant with the largest flower cluster in the world.
The tiniest fish varies depending on who you ask.
The competition for the title of the smallest fish in the world is highly debated. As stated by Guinness World Records, the current record holder is the male Photocorynus spiniceps, measuring just 6.2mm. This species of deep-sea anglerfish can be found in the Philippine Sea and is known for its parasitic mating behavior. The male attaches itself to a significantly larger female, a common trait in anglerfish, and essentially turns her into a hermaphrodite. The female takes on the responsibility of feeding, swimming, and ensuring their survival, while the male focuses solely on reproduction.
However, some scientists argue that the title of “smallest fish” should be given to the Paedocypris progenetica from Sumatra, which can grow up to 7.9mm in length and lives in peat bogs. This species was officially named and recognized as the smallest fish in 2006, but its title was contested by researchers studying the anglerfish.
The tiniest cactus is Blossfeldia liliputana, found in Argentina and Bolivia.
According to Paul Rees, a nursery manager at Kew Gardens, the name of the Blossfeldia liliputana species originates from the term “lilliput,” which describes a small person or creature. Rees also mentions that it is a reference to the fictional land of tiny inhabitants in the novel Gulliver’s Travels.
The world’s smallest cactus, which is able to survive in harsh conditions and is typically found on rock surfaces and in crevices at high elevations in Bolivia and Argentina, is facing growing danger from collectors. It can endure severe drought by losing up to 80% of its water content.
“In recent years, this particular species has become highly sought after by collectors. Unfortunately, its slow growth rate has led to a significant number of plants being illegally taken from their natural habitat. Despite being classified as ‘least concern’ due to its widespread distribution, poaching continues to be the greatest danger to the survival of this species.”
Tiny fungi: awaiting discovery
Last year, a photo of the small Mycena subcyanocephala in Taiwan gained popularity on social media, leading some to mistakenly claim it as the world’s smallest. However, according to Ester Gaya, the senior research leader in mycology at Kew Gardens, there may be countless microscopic organisms waiting to be discovered among the estimated 2 million species of fungi.
“Mycena subcyanocephala is one of the smallest species of fungi in the world. Regardless of their minute size and ethereal looks, this species of fungus plays its role in the complex recycling system of nature. Mycena species are saprobes, meaning they live on decaying organisms, helping clear our woods of unwanted ‘litter’.”
According to her, small fungi play a crucial role in our ecosystems by performing tasks such as nutrient recycling and carbon sequestration. This highlights the significant impact that multiple small fungi working together can have.
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