Welcome to the Incredible World of Mammals
Introduction
Look around you sometime, the chances are that if you see an animal it is a
mammal. Mammals are the dominant life form on this planet at the moment,
at least from a human perspective.
There are about 4260 species of mammals known on this planet at the moment,
though taxonomists are still arguing and species are still being found. Who are
the
21st Century Mammals?
21st Century Mammals?
Mammals are not the most speciose animal group on the planet, three other
groups of vertebrates out-number them at the moment, Reptiles 6787 species,
Birds 9703 species and Fishes with approximately 32000 species. Invertebrates,
of course, have groups with huge numbers of species that outnumber all the
vertebrates put together; Molluscs 80 000 and Insects 1 000 000; while
Arachnids with a mere 44 000 species still outnumber any 3 groups of
vertebrates put together. Mammals however are big. You can see them easily, and
perhaps most importantly you are one.
Mammals are there, everywhere you look; large warm-blooded, four-limbed
vertebrates whose females produce milk (see What is a Mammal).
Elephants and Whales, Pigs, Horses, Cattle, Sheep, Dogs, Cats, Hamsters, Rats
and of course Human beings (that's you and me) are all mammals.
Mammals are friendly or fierce, cuddly, cute and/or awesome depending on
which ones you look at. They fascinate and horrify us. We eat them, ride them,
keep them as pets, makes clothes out of them, hunt other mammals with them and
use them as substitutes for ourselves in scientific, particularly medical,
research. We use them to carry our burdens, support our foolish habits
(gambling) and expect them to entertain us. To most people animals are mammals.
Most people are totally dependent on non-human mammals to keep their lives
functioning (Vegetarians and Vegans excepted) and many of us need them as
emotional supports as well. We are mammals (genetically a man and his dog are
97% the same) and we love them because they are like us. We use them to
describe people (someone is a dog, bitch, stallion, pig, cow, kitten, bunny; we
run like a rabbit, weasel out of a deal or are as sly as a fox, strong as an
Ox, and can have a whale of a time, etc). Our mammalian cousins are very
important to us. But how much do you really know about what it takes to be a
mammal??????
Mammals may have only become successful as a group relatively recently, but
they have been around a long time. The first mammals appeared about 265 million
years ago, a mere 10 million years after the first dinosaurs, but they remained
relatively obscure for the first 160 million years while the dinosaurs ruled
(see The Evolution of
Mammals).
Some Amazing Mammals
The Blue Whale, Balaenoptera musculus, is the largest mammal living
today. It is also the largest mammal to have ever lived. In fact the Blue whale
is the largest animal ever to have lived on the planet as far as we
know; bigger by far than even the largest Dinosaur. The longest Blue Whale ever
measured was a female, 33.58 m or 110ft long. The heaviest weighed over 190
tonnes. We haven't actually got a set of weighing scales big enough so weights
are estimated from the cut up remains.
The largest animal on land at the moment on this planet is a mammal; the
bull African Elephant. The largest specimen recorded stood around 3.96 m or
13ft at the shoulder and weighed over 12 tonnes.
The tallest animal on the planet is a mammal - Giraffes, Giraffa
camelopardalis, can be 6.1m or 20ft tall.
The smallest mammal in the world is a bat from Thailand, Kitli's Hog-nosed
Bat, Craseonycteris thonglongyai, being only 2.9-3.3 cm or 1.14-1.3
inches long and weighing a mere 1.7-2 g or 0.06 - 0.07oz this bat is well
smaller than many insects and snails.
In a close 2nd place, the Pygmy or Savi's White-toothed Shrew Suncus
etruscus weighs in at 1.5 - 2.5 grams or 0.05 - 0.09oz and isdefinitelyy
the smallest land mammal on record.
The Cheetah, Acinonyx jubatus, is the fastest animal on land,
reaching speeds as fast as 96 kmh or 60 mph. The fastest mammal in the water is
the Killer Whale, Orcinus orca, which has been recorded swimming at
speeds of 55.5 kmh or 34 mph. The fasted mammal in the air is the Big Brown
Bat, Eptesicus fuscus, with a recorded flight speed of 25 kmh or 15.5
mph.
The longest lived mammals are not human beings as many people think, but the
whales. Fin Whale Balaenoptera physalis is believed to have a maximum
life-span of 90 - 114 years, a little less that the human maximum, but Bowhead
Whales (Balaena mysticetus), also known as Greenland Right Whale
has been known to live to at least 170 and possibly more than 200 years since
the mid 1990s.
Rhinoceroses have the thickest skin of any terrestrial mammal, and the
thickest skin in relation to their size, of any animal. The skin on their backs
and flanks can be 2.5 cm or 1 inch thick.
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