75+ Interesting Facts About Mammals

  1. Distinguishing features in mammals are body hairs, mammary glands, and the neocortex (part of the brain with higher intelligence functions).
  2. Only around 5% of mammals are monogamous. Comparatively, this sexual behavior is present in nearly 90% of species of birds. (Source)
  3. Suicidal reproduction, semelparity, is prevalent in plants, fish, insects, and reptiles. But there are only four mammal species that mate themselves to death to survive their genes. All these four species belong to insect-eating marsupials. (Source)
  4. Some mammals have the best night vision among animals. These include large-eyed mammals (raccoons, tarsiers, opossums, and night monkeys), red foxes, snow leopards, etc. (Source)
  5. Reindeers, bats, and a few rodents are the only mammals that can see ultraviolet (UV) light. (Source)
  6. Monotremes and dolphins are the only mammals with a sense of electroreception. They use electric fields generated by the muscular contractions of their prey to locate them. (Source)
  7. Primates (a mammalian order that also includes humans) are the most violent creatures in the animal kingdom. Members of this order kill six times more of their species than other mammals. (Source)
  8. There are more than 5,000 species of mammals on earth. According to estimates, Scientists have not discovered more than 300 species of mammals yet. (Source)
  9. Most mammals are land-based, but there are also marine and flying mammals. Bat is the only living mammal that can fly, while whales, seals, and manatees are examples of aquatic mammals.
  10. Hairs are present only in mammals. All mammals possess hair at some point in their life. Hairs provide camouflage, insulation, and other benefits to mammals. Spines and quills in a few mammals are also stiffened and strengthened hairs. (Source)
  11. Horses have the largest eyes of all land mammals. These eyes, around 1.34 inches in diameter, are also one of the largest eyes in the animal kingdom. Horses can easily see nearly every part of their body and things around them through these large eyes. (Source)
  12. The sperm whale has the largest brain of any animal (avg. 7.8 kg). It is five times heavier than the human brain. (Source)
  13. The Long-snouted Spinner dolphin has 252 teeth, the highest among mammals. Giant armadillos have the highest number of teeth among land mammals, with up to 100 teeth. (Source)
  14. Cattle and dear align themselves according to the earth’s magnetic field while grazing or sleeping. They face either north or south during these tasks. (Source)
  15. According to experiments, almost all species of mammals can swim. Only giraffes and great apes can’t swim. (Source)
  16. The blue whale is not only the largest mammal but also the largest animal ever to exist on the earth. (Source)
  17. The bumblebee bat (also known as the hog-nosed bat) is the smallest mammal, having a body length of 29-33 mm and a weight of 1.7-2 g. The Etruscan shrew (or Savi’s white-toothed pygmy shrew) is the smallest non-flying mammal. It can attain a body length and weight of 25-30 mm and 1.5-2.5 g. (Source)
  18. Humans share 96% of genes with chimpanzees, 90% with domestic cats, 85% (protein-encoding genes but only 50% non-coding genes) with mice, and 80% of genes with domesticated cattle. (Source)
    A large bull
    Domesticated cattle share 80% genes with humans

  19. The first winged mammals appeared around 160 million years ago in China. These wings were helpful for these ancient mammals to glide. (Source)
  20. Rodents are the largest mammalian order with more than 2,000 species. Chiroptera (bats) is the second largest order of mammals, having above 1,100 species. These two orders contain more than 50% of mammalian species.
  21. Cats, rats, and pigs are the worst invasive species in the world. Feral cats are responsible for the extinction of 63 species (40 birds, 21 mammals, and two reptile species). Thirty mammalian predator species have caused the extinction of 142 birds, mammals, and reptile species. (Source)
  22. The majority of mammals give birth to their offspring, but five species of monotreme mammals (platypus, spiny anteaters, etc.) lay eggs.
  23. Monotremes are the oldest living mammals on earth. They have been present on earth for more than 110 million years. Other oldest mammals are solenodon (73 million years) and elephant shrews (around 47 million years). (Source)
  24. Studies show that ancestors of monotremes also knew the art of suckling milk. They later lost this ability with time. (Source)
  25. Arctic ground squirrels have the lowest body temperature among mammals. Their temperature can drop to -2.9 C during the hibernation period. (Source)
  26. According to research, mammals acquired the feature of warm-bloodedness around 252 million years ago. The development of this feature was the result of a change in the climate of the earth. (Source)
  27. Most mammals are warm-blooded (endothermic) and can adjust their body temperature according to the change in climate or weather.
  28. Elephants can hear thunderstorms at a distance of 500 km due to infrasonic hearing (low-frequency sound). They also use this ability to communicate with each other over long distances. (Source)
  29. The upper hearing limit in humans is 20 kHz. Comparatively, the upper hearing limit is 45 kHz in dogs, 64 kHz in cats, over 100 kHz in bats, and 160 kHz in porpoises (marine mammals). 
  30. Tarsiers have the most flexible neck in the mammal kingdom. This animal can turn its head 180 degrees on both sides. (Source)
  31. Almost all mammals have seven vertebrae in their necks, regardless of size. But there are at least two exceptions to this rule. Sloths have 5 to 9 cervical vertebrae, while manatees also have fewer than normal vertebrae in their necks. (Source)
  32. There are very few venomous mammals present on earth. Venom is present in three types of mammals: insectivores, monotremes, and bats. (Source)
  33. Opossums, mongooses, hedgehogs, and a few other mammals have toxin-neutralizing serum proteins in their bodies. They provide resistance against snake venom. (Source)
  34. Opossums are immune to almost all types of venom. Research is underway to use a protein in opossums as an anecdote to snakebites and other venoms. (Source)
  35. Opossums are famous for playing dead when in danger. However, this feature is also present in several other mammals, such as guinea pigs and some species of rabbits. (Source)
  36. Giant pandas have the digestive system of a carnivore. However, nearly 99% of their diet consists of plants, particularly bamboos. 
  37. Saiga is a strange antelope that distinguishes itself with its protruding nose. This nose is helpful for this animal as it filters out dust and warms the air in the winter. 
  38. Like most birds, few mammals can also sing. Mice, bats, and whales are the most famous mammals known for their singing abilities. (Source)
  39. Bowhead whales are called jazz singers of the Atlantic. The males of these marine mammals can produce new songs every new season. These are the only mammals that can sing various songs in different seasons. (Source)
  40. Mammals cannot breathe underwater, while aquatic mammals can hold their breath underwater for different periods. The Cuvier’s beaked whale can dive for 222 minutes, the longest among mammals. Sperm whales (90 minutes) and harbor seals (30 minutes) also have exceptional breath-holding abilities. Humans can hold their breath for 30 to 90 seconds. (Source)
  41. Hippopotamus has the largest mouth of land animals. This African mammal can open its mouth at almost 1800 and reaches an average gape of 1.2 m (4 ft.). (Source)
  42. The Tasmanian devil has the most powerful bite per body weight among all mammals. This bite (553 N) allows a 6-kg-weigh devil to kill a 30-kg wombat.
  43. African elephants have the strongest smell among mammals, while rats, mice, and cows are better sniffers than dogs. (Source)
  44. The largest land-based mammal, the African bush elephant, is also the largest animal on land. Giraffe, a mammal, is the tallest living animal on land.
  45. Pangolin is the only mammal possessing tough and flexible keratin to protect its skin. Further study of this feature may help develop the latest human body armor. (Source)
  46. The African spiny mouse is the only mammal that can completely regenerate its damaged tissues. (Source)
  47. Water shrews can walk on the surface of the water. They can do so thanks to stiff hairs on their feet that can trap air bubbles. (Source)
  48. Tree shrews are the only known mammals besides humans that like to eat spicy food. (Source)
  49. The pygmy shrew has the fastest heartbeat of any animal. Its heart rate is 1,200 beats per minute. (Source)
  50. Common shrews shrink their heads (skull and brain) along with spines, heart, spleen, and lungs during the winter season. Reducing vital organs allows this tiny mammal to save energy and survive winters. The skull regenerates in spring but cannot attain its original size again. (Source)
  51. Sand gazelle, a mammal in the Arabian Desert, can shrink its liver and heart during drought. It allows them to breathe less, which results in less respiratory evaporation. (Source)
  52. The hooded seal has the shortest lactation period among all mammals. This marine mammal provides milk to its baby for just 3 to 5 days. (Source)
    A hooded seal on snow
    Hooded seal has the shortest lactation period among mammals

  53. Hooded seals produce the fattiest milk on earth, containing 60% fat. On the contrary, black rhinos’ milk has just 0.2% fat. Most protein-rich milk belongs to the eastern cottontail rabbit, with 15% protein content. Milk of Tammar wallabies contains 14% sugar. These mammals can also produce two different types of milk according to the ages of their babies. (Source)
  54. Apart from humans, a few other mammals also possess fingerprints. These are chimpanzees, gorillas, and koalas. Fingerprints are not present in any other animal. (Source)
  55. Mammals occupy the top spots with the best memory in the animal kingdom. Dolphins have the longest social memory among animals, while elephants and squirrels also have exceptional memories. (Source)
  56. Armadillo has a strong outer shell that protects its body. Sometimes, even a bullet can’t penetrate this shell. (Source)
  57. The marine otter, also called the sea cat, is the smallest sea-dwelling mammal. It can measure up to 15 cm (less than 4 ft.) in length and weighs around 11 lbs (5 kg). The second-smallest marine mammal is the sea otter. (Source)
  58. Dolphins and seals are among a few animals that sleep with one eye open and half a brain awake. They do so to avoid predators and perform other necessary tasks while sleeping. (Source)
  59. Bornean Orangutan is the slowest breeding mammal on earth. A female orangutan gives birth once after 6 to 8 years after reaching sexual maturity. Giant pandas, polar bears, African elephants, cheetahs, and gorillas are also slow-reproducing mammals. (Source)
  60. Mammal is the only major vertebrate group where asexual reproduction hasn’t been observed. All mammals reproduce sexually. (Source)
    Asexual reproduction by budding
    All vertebrates can reproduce asexually except mammals

  61. Embryonic diapause is a reproductive strategy used by several mammals to suspend embryonic development at the blastocyst stage. This procedure is present in more than 130 mammal species, including mice, badgers, bears, marsupials, etc. The cell division and metabolism reduce to minimum levels during this process that can continue for a year. This practice does not produce any harmful effects on pregnancy. (Source)
  62. A semi-aquatic rodent from Venezuela has the highest number of chromosomes among mammals. The number of diploid chromosomes in Ichthyomys pittieri (commonly known as Pittier’s crab-eating rat) is 2n = 92. (Source)
  63. The common dolphin is the fastest marine mammal. It can swim at a speed of 64 km/h. Killer whales (53 km/h) and sea lions (35 km/h) are the 2nd and 3rd fastest mammals in oceans. (Source)
  64. Whales and dolphins respond differently when they hear loud noises from ships. Bottlenose dolphins increase the frequency of their whistles (as they are shouting), while humpback whales stop singing. (Source)
  65. The vampire bat is the only known mammal whose diet is solely composed of blood. They do so by taking advantage of their razor-sharp teeth and anticoagulant saliva. (Source)
  66. An anteater eats around 30,000 insects (termites and ants) daily. Other famous insect-eating mammals are armadillos, pangolins, numbats, and echidnas.
  67. Beaver, a semi-aquatic rodent, can build gigantic dams for protection against predators. The world’s biggest beaver dam has been discovered in a remote location in Canada. This 850-meter (2,800-foot) long dam is also visible from space. (Source)
  68. Puma (mountain lion) can achieve the highest jump among mammals. The highest recorded jump by a mountain lion is 7 m (23 feet). (Source)
    A rabbit sitting
    Rabbits and hares are known for their always growing teeth

  69. The teeth of rodents (rats, mice, etc.) and lagomorphs (rabbits and hares) grow continuously throughout their lives.
  70. Almost all mammals, regardless of size, take around 12 seconds to defecate. (Source
  71. The urination time for mammals (larger than rats) is slightly higher at 21 seconds. (Source)
  72. Tails play a significant role in keeping rats cool. The tail comprises only 5% of a rat’s body, but it can relieve 17% of its body heat.
  73. Mice have several facial expressions. Like humans, mice also express their emotions through facial expressions. (Source)
  74. Rats and mice are clean animals. It is less likely to get parasites and viruses from rats and mice than from cats and dogs. (Source)
  75. The first mammal in space was a rhesus monkey named Albert 1. It was on board a US-launched V2 rocket in June 1948.
  76. The 1st animal to orbit earth was a mammal. A dog named Laika was on board the Soviet satellite, Sputnik 2, on 3rd November 1957.


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