85 Interesting Facts About Mammals

  1. Special 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. Cats have the best eyesight among mammals at night. They can do so by expanding their pupils in the dark. (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, more than 300 species of mammals haven’t been discovered 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 marine 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. According to experiments, almost all species of mammals can swim. Only giraffes and great apes can’t swim. (Source)
  15. The blue whale is not only the largest mammal but the largest animal ever to exist on the earth. (Source
  16. The killer whale, another marine mammal, is the only animal that can attack blue whales. (Source)
  17. 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

  18. The first winged mammals appeared around 160 million years ago in China. These wings were helpful for these ancient mammals to glide. (Source
  19. Chiroptera is the second largest order of mammals, with more than 1,200 species. This order is comprised of bats.
  20. 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)
  21. The majority of mammals give birth to their offspring, but five species of monotreme mammals (platypus, spiny anteaters, etc.) lay eggs.
  22. Monotremes are the oldest living mammals on earth. They have been present on earth for more than 110 million years. They are followed by solenodon (73 million years) and elephant shrews (around 47 million years). (Source)
  23. Studies show that ancestors of monotremes also knew the art of suckling milk. They later lost this ability with time. (Source)
  24. The smallest mammal is a hog-nosed bat (also known as a bumblebee bat).
  25. The mammal with the lightest weight is the Etruscan shrew (1.8 g weight).
  26. 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)
  27. 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). 
  28. Tarsier has the most flexible neck in the mammal kingdom. This animal can turn its head 180 degrees on both sides. (Source)
  29. An anteater eats around 30,000 insects (termites and ants) daily. (Source)
  30. The vampire bat is the only known mammal whose diet is solely composed of blood. (Source)
  31. Arctic ground squirrels have the lowest body temperature among mammals. Their temperature can drop to -2.9 C during the hibernation period. (Source)
  32. According to research, mammals acquired this 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)
  33. Most mammals are warm-blooded (endothermic) and can adjust their body temperature according to the change in climate or weather.
  34. But there is also an exception to this rule. Few mammals are either cold-blooded or in between warm-blooded and cold-blooded metabolism. Squirrels, bats, and naked mole-rat are a few such examples. (Source
    Naked mole rat eating
    Naked mole rat is one of few non warm-blooded mammals

  35. While grazing, cattle and dear align themselves according to the earth’s magnetic field(Source)
  36. The African spiny mouse is the only mammal that can completely regenerate its damaged tissues. (Source)
  37. Almost all mammals have seven vertebrae in their necks, regardless of size. But there are at least two exceptions to this rule. Sloths can have 5 or 6 vertebrae, while manatees can have 8 or 9 vertebrae in their necks. (Source)
  38. There are very few venomous mammals present on earth. Mammal species that possess venom include hedgehogs, moles, shrews, vampire bats, male duct-billed platypuses, and a few others. (Source)
  39. Opossums, mongooses, hedgehogs, and a few other mammals have toxin-neutralizing serum proteins in their bodies that provide resistance against snake venom. (Source)
  40. Opossum, a mammal, pretends to be dead by lying motionless and secreting the smell of a corpse while in danger. It saves this mammal from animals who like to eat their prey. 
  41. 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)
  42. A single opossum can kill and eat 5,000 ticks in a season. Opossums kill around 90% of the ticks at the place of their presence. (Source)
  43. Due to very little body fat, Shrews can’t remain foodless for more than a few hours, which can prove fatal. 
  44. 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. 
  45. Like most birds, few mammals can also sing. Mice, bats, and whales are the most famous mammals known for their singing abilities. (Source)
  46. 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)
  47. Mammals can’t breathe underwater. Marine mammals can hold their breath underwater for different periods. Elephant seals can hold their breath underwater for 2 hours. Sperm whales and Weddell seals have this ability for 90 and 70 minutes, respectively. (Source)
  48. 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)
  49. The Tasmanian devil has the most powerful bite per body weight among all mammals. This bite allows a 6-kg-weigh devil to kill a 30-kg wombat. (Source)
  50. African elephants have the strongest smell among mammals, while rats, mice, and cows are better sniffers than dogs. (Source)
  51. The largest land-based mammal, the African bush elephant, is also the largest animal on land. 
  52. Giraffe, a mammal, is the tallest living animal on land.
  53. 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)
  54. Bears are quadrupeds (walk on four limbs) but can sit and stand like humans. Standing on two legs increases their ability to sight, hear and smell. Standing doesn’t mean the animal is going to attack. (Source)
  55. 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)
  56. Tree shrews are the only known mammals besides humans that like to eat spicy food. (Source
  57. The pygmy shrew has the fastest heartbeat of any animal. Its heart rate is 1,200 beats per minute. (Source)
  58. 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)
  59. 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) 
  60. Almost all mammals, regardless of size, take around 12 seconds to defecate. (Source
  61. The urination time for mammals (larger than rats) is slightly higher at 21 seconds. (Source
  62. 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

  63. The fattiest milk on earth is produced by hooded seals that contain 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)
  64. 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)
  65. Mammals occupy the top spots with the best memory in the animal kingdom. Dolphins have the longest memory among animals, while elephants, primates, and whales also have exceptional memories. (Source)
  66. Due to the structure of their necks, pigs can’t look at the sky while standing.
  67. Armadillo has a strong outer shell that protects its body. Sometimes, even a bullet can’t penetrate this shell. (Source)
  68. 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)
  69. Dolphins (and a few other marine mammals) keep one of their eyes and half-brain open while sleeping. It helps the mammal control its breathing and sense any danger. (Source)
  70. 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)
  71. 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

  72. 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)
  73. 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)
  74. The common dolphin is the fastest marine mammal. It can swim at a speed of 64 kph. Killer whales and sea lions are the 2nd and 3rd fastest mammals in oceans. (Source)
  75. 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)
  76. According to the latest research, a small black-footed cat is a deadliest and most dangerous cat on earth. This tiny cat, found only in a few southern African countries, can hunt more than ten birds and rodents a night. A leopard can do so in six months. Its success rate of hunting is 60% compared to 25% that of a lion. (Source)
  77. 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 meters (2,800 feet) long dam is visible from space. (Source)
  78. Giant pandas have the digestive system of a carnivore, but bamboo forms 99% diet of these pandas. (Source)
  79. White-tailed jackrabbits and brown hares have the highest and longest jumps in the animal kingdom. White-tailed jackrabbits can cover a distance of 6.4m (21 ft), while brown hares can attain a height of 4.5m (15 ft) in their jump. (Source
    A rabbit sitting
    Rabbits and hares are known for their always growing teeth
  80. The teeth of rodents (rats, mice, etc.) and lagomorphs (rabbits and hares) grow continuously throughout their lives.
  81. 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.
  82. Mice have several facial expressions. Like humans, mice also express their emotions through facial expressions. (Source)
  83. 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)
  84. 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. (Source)
  85. The first mammal in space was a rhesus monkey named Albert 1. It was on board a US-launched V2 rocket in June 1948. (Source)


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