Mammals are a diverse and widespread class of vertebrate animals characterized by having hair, three middle ear bones, mammary glands in females, and a neocortex region in the brain. Determining exactly how many mammal species exist on Earth has been an ongoing effort by biologists and taxonomists for centuries.
Even today, new mammal species are still being discovered and described. However, scientists have been able to provide estimates on the total number of existing mammal species.
Currently, there are approximately 6,400 known mammal species that have been identified and described.
This number comes from the Mammal Species of the World, a standard reference guide on mammal taxonomy that is published by the Smithsonian Institution and the American Society of Mammalogists. The guide, which is in its 3rd edition, lists and classifies all scientifically recognized mammal species.
The 6,400 species span 29 different orders, which contain a wide variety of forms and traits. Some of the largest orders include rodents (2,000+ species), bats (1,200+ species), even-toed ungulates (250+ species), and primates (500+ species).
The diversity of mammalian adaptations is immense, ranging from the bumblebee bat weighing less than a penny to the blue whale reaching up to 110 feet long.
However, this number of 6,400 described species likely underestimates the true mammal diversity on Earth. The International Union for Conservation of Nature (IUCN) estimates there are actually around 6,500 known mammal species. But they also calculate there are probably over 1,200 undiscovered mammals waiting to be found and documented, putting the total number of actual mammal species at approximately 7,700.
The majority of unknown diversity is expected to be smaller species concentrated in remote tropical locations and difficult-to-access habitats. Hundreds of new mammals are described each decade, so as exploration continues, more species will be added to the scientific record.
Other unknown diversity may come from cryptic species that are morphologically similar but reproductively isolated. Advances in genetic analysis continue to uncover cryptic diversity among mammals.
In last, there are about 6,400 currently recognized mammal species, but taxonomic evidence predicts the actual total diversity is likely between 7,500-8,000 species or more. As mammalogy persists as an active field of biology, our knowledge of global mammal diversity will continue growing as new discoveries are made in the world’s remaining frontier habitats.
FAQs;
Q: How many different species of mammals are there?
A: Currently there are around 6,400 scientifically documented mammal species. However, estimates suggest the actual total could be over 7,700 when including undiscovered species.
Q: What country has the most mammal species?
A: Indonesia likely has the most mammal species diversity, with around 700 known species. Many remain undiscovered in Indonesia’s tropical forests.
Q: What mammal order has the most species?
A: The order Rodentia (rodents) has the highest number of mammal species at over 2,000. Bats, even-toed ungulates, and primates also have high diversity.
Q: Are new mammal species still being discovered?
A: Yes, new mammal species are discovered frequently, especially smaller mammals in tropical regions. Over 100 new species are described each decade.
Q: What is the largest mammal species?
A: The blue whale is the largest mammal and animal species ever known, growing up to 110 feet long.
Q: What is the smallest mammal species?
A: The Etruscan shrew is the smallest known mammal by mass, weighing around 2 grams. The bumblebee bat is the smallest by length at about 1.5 inches.
Q: How many mammal species are threatened or endangered?
A: According to the IUCN Red List, over 1,200 mammal species are threatened with extinction, including 25% of all primates.
Q: What mammal has gone extinct most recently?
A: The baiji or Yangtze river dolphin was declared functionally extinct in 2006 after an extensive survey failed to find any individuals.
Q: How many new mammal species are identified each year?
A: On average, around 150-200 new mammal species are scientifically described and named annually. Most are small rodents, bats, and other difficult-to-observe mammals.
Q: Which continent has the most mammal diversity?
A: Africa is considered the most mammal-diverse continent, with over 1,100 known species. Asia, South America, and North America also have high mammal diversity.
