Mammals are warm-blooded, covered with hair, bear live young, and produce milk to feed them, and we like to think of ourselves as the best mammal around. However, in many categories other animals have us beat, paws down.
Some people argue that a vegetarian diet can't support a large life-form. They obviously haven't met the blue whale (Balenoptera musculus), a massive creature that survives on plankton.
Weighing in at 150 tons, the blue whale isn't only the largest mammal but, in fact, the largest animal known. Its ability to maintain life on such a grand scale is aided by its oceanic lifestyle.
In comparison, the bull African elephant (Loxodonta Africana) is the largest land animal, and it weighs a mere 12 tons.
The title "smallest mammal" is only slightly smaller than the animal it describes. A native of Thailand, measuring 1.14-1.3 inches and weighing 0.06-0.07 ounces, Kitti's hog–nosed bat (Craseonycteris thonglongyai), or bumblebee bat, truly earns its title.
The smallest land mammal, the pygmy shrew (Suncus etruscus), is only slightly larger, tilting the scales at a heft 0.05-0.09 ounces. These pipsqueaks are so small that they're outweighed by two standard paperclips.
Even though their diminutive stature places them eye to eye with many snails and insects, these two animals are true warm-blooded vertebrates: they are covered with hair, and their females produce milk - mammals to the core.
As might be expected, the winner in this category depends on the terrain. Mammals are found in the air, water, and land, and each domain requires different types of locomotion skills.
The fastest air mammal is the big brown bat (Eptesicus fuscus), which can flap its way up to 15.5 miles per hour. The fastest water mammal reaches a significantly higher 34 miles per hour - and at this speed the killer whale (Orcinus orca) can definitely have its choice of the catch of the day.
However, clocking in at 70 miles per hour, the overall fastest mammal is a land creature, the cheetah (Acinonyx jubatus). Due to the amazing amount of energy required, this cat can pour on the power only for short periods of time, but that's of little comfort to gazelles it sets its sights on.
In a competition over slowness, three animals come to mind: the tortoise, the sloth, and the snail. Of these contestants the snail is definitely the winner hands down. The garden snail clocks in at a molasses-like 0.03 miles per hour. Moving at a steady pace, it would take the snail 12.5 hours to go around a standard city block.
However, the category is the slowest mammal, and snails (and tortoises) aren't mammals. On that technicality the three-toed sloth (Bradypus variegates) pulls into the winner's circle.
Three-toed sloths, believe it or not, have three toes and spend the vast majority of their lives in the rain forests of Central and South America. These speedsters register 0.15 miles per hour, making then 5 times faster than the garden snail but 467 times slower than the cheetah.
No, this award doesn't refer to mental capacity; that could be a much tougher call. The rhinoceros (Diceros bicornis michaeli) is the land mammal with the thickest skin of any animal. Rough boss, critical spouse - with 1-inch-thick skin, these tough guys can handle it all. Well, maybe not the boss.
Strange But True: X-Treme Mating
The male platypus is one of only two known venomous mammals. The venom, however, is delivered not by fangs but by retractable spurs on the male platypus' hind legs.
Even stranger, these spurs aren't really used on predators and prey. Instead, platypus venom is reserved for battles with rival males during what must be an extreme mating season.
In the very few documented cases where humans have been envenomed, the results were intense. The unfortunate victims reported tremendous pain that did not respond to morphine and lingered for months.
From mental_floss' book Condensed Knowledge: A deliciously Irreverent Guide to Feeling Smart Again, published in Neatorama with permission. Original article written Karen Bernd.
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The major reason why blues and other whales can get so big has nothing to do with their diet. It is that water supports their weight, so their skeleton doesn't have to.
The weight of an animal goes up with its volume, which is measured in meters cubed, while the strength of its bones goes up (roughly speaking) with its cross section, which is measured in meters squared. As an animal gets bigger and bigger, the bones required to support its weight must get bigger, faster, until eventually the animal reaches a practical size limit, where as much of it is bone as possible (and it is virtually a stationary tower.) (And that, by the way, is why you cannot have an ant the size of a skyscraper, 50's horror movies aside. If you just scaled up the ant, the weight would go up faster than its structural strength. A skyscraper ant would collapse on its belly, immobile.)
But with whales and other creatures whose weight is supported by water, the limit is set by availability of food, and that is a very high limit. I imagine even larger animals than blue whales could evolve, eventually.
Incidentally, that is also why bigger dirigibles are more cost-effective than small ones. You can double the fabric in a dirigible, and get much more than double the lifting power.
Viva la beef