UNBELIEVABLE: Interesting strange animals | History Defined

It's highly unlikely you'll see every type of animal on the planet. And that's because there are just too many. The International Union for Conservation of Nature (IUCN) is the global authority on the status of the natural world and the measures needed to safeguard it.

It tracks the number of described species and updates this figure annually based on the latest work of taxonomists. In case you're wondering, taxonomists are biologists who specialize in identifying and classifying life on the planet.

In 2022, the IUCN listed 2.16 million species on earth. This included 1.05 million insects, over 11,000 birds, more than 11,000 reptiles, and more than 6,000 mammals. And those are only the ones known to experts.

In 1998, the National Wildlife Federation (NWF) noted that "more than 200 years after biologists began naming and classifying the world´s plants and animals, they still do not know how many species exist. Estimates range from 3 million to 100 million or even more."

The NWF said that around 13,000 more species are added to the list of known creatures every year. And while a large portion of the world´s mammals, birds, reptiles, amphibians and flowering plants are named, there are loads more species to be listed.

"The lion´s share of unknown species are small, mostly microscopic organisms that live in some of Earth´s least-accessible habitats: beneath the ground, in the deep sea, in the crowns of tropical trees, and on the backs or in the guts of other creatures," explains the NWF.

"Such insects, worms, mites, fungi, bacteria and other tiny life forms are what Harvard University biologist Edward O. Wilson calls 'the black hole of taxonomy.' Unimaginably abundant, their numbers could alter overall species totals by a factor of 10 or more," it adds.

A 2018 PLOS Biology study revealed that 86% of all land and 91% of sea species had not been discovered yet.

When it comes to the number of animals, not species, here a few fun facts... Chickens outnumber humans on earth by a staggering four chickens to each person on earth. "That translates into 26.5 billion chickens for 8.1 billion humans," notes the World Animal Foundation (WAF).

The most common animal in the world is the ant, says the WAF. "With an estimated population of around 10 quadrillion (10,000,000,000,000,000) individuals, ants are incredibly numerous and found in almost every terrestrial habitat on Earth," reads the site.

"When it comes to creatures that are not big or fuzzy, what we don´t know is a percentage somewhere in the double digits," says director of the Texas Memorial Museum and president of the Association of Systematics Collections (ASC), Edward Theriot.

A sentiment echoed by George Washington University microbiologist Diana Lipscomb. "We don´t even know enough to tell you what we don´t know," she said.