Mammals with different traits

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What are mammals? They are the most recent of all the animal lineage, believed to have evolved from an extinct group of reptiles some 200 million years ago, during the age of dinosaurs, according to scientists. Mammals differ from other groups of animals due to many reasons.

Do you know how and why they are different? Mammals are the only creatures that bring forth live young and also feed them on secretions produced by the mammary glands. In fact, the name mammal is derived from these special mammary glands. By now, you must be aware that we humans too belong to this group of animals.

However, these two factors are not the only ones that make mammals different from other animals. Mammals have hair or fur instead of feathers and scales, they are able to maintain their body temperature at a constant level (even birds can do so).They have sweat glands to help cool their bodies, and also flexible skin. Today we feature some interesting facts about some of these mammals.

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Short-tailed Shrew

The only mammal with a venomous bite

This shrew is unique among the mammals in having glands in its mouth that produce a powerful nerve poison: a single bite is sufficient to kill a small mammal in a few seconds.

The Short-tailed Shrew (Blarina brevicauda) is one of just two species of shrew-like insectivores that are found only in North America. It spends most of its time in subterranean burrows and runways, but, in winter, it may burrow through the surface snow cover as though it were soil.

It hunts for its food on the surface and may even climb into bushes in its search for tasty morsels. One was once observed climbing 1.9 m (6 ft) up a small tree to get at some suet placed in the fork of a branch.

The poison with which this small predator subdues (overcomes) its prey is present in the saliva in its mouth, and seeps into the puncture wounds made by its teeth when it bites its prey. The poison is so powerful that it will leave a bite that is very painful for several days even in an animal as large as a man.

To help see it through the winter when food is hard to find, the shrew will sometimes hoard (store) snails, beetles and seeds.

Each individual occupies an area of about 0.12 ha (0.3 acres), where it builds its nest of dry leaves under fallen logs or tree stumps.

Profile

Length: 75-105 mm (3-4 in), with a tail of 17-30 mm (0.5-1.2 in).
Weight: 15-30 g (0.5-1.0 oz).
Distribution: Throughout southern Canada and most of the USA.
Habitat: All types of terrestrial habitat.
Breeding: 3-9 young in a litter; births can occur any time from early spring to
autumn; females may produce several litters each year.
Diet: Invertebrates, small vertebrates and some plant matter.
Longevity: 2.5 years.
Notes: Males can breed as little as 50 days after birth.

Colugos - The mammal that wraps itself in a cloak

Like a voluminous (bulky) cape, the thin flaps of skin between the colugo's extremities have to be tucked up under its arms to avoid being caught on twigs while the animal is climbing trees.

The two closely related species of colugo or flying lemur (Cynocephalus volans and C. variegatus) are the only living representatives of their order, the Dermoptera. Their relationship to other mammalian groups has long been a source of mystery, and different authorities have classified them with the true lemurs (in the order Primates) and with the insectivores.

They are now generally considered to form a separate primitive order of their own. Colugos are characterised by the loose flaps of skin that join all their extremities, from the neck, through the wrists and ankles to the tip of the tail. When the animal stretches out its limbs, these flaps of skin form a taut (tightly drawn) gliding platform on which it can 'fly.'

Almost helpless on the ground, colugos will try to climb any vertical object near them. Once in a tree, they climb swiftly to the top and launch themselves into the air in a long shallow dive, to land in a tree or bush some distance away.

With their large gliding flaps, the colugos are the most efficient of all the gliding mammals and can cover long distances. One was once recorded as covering a horizontal distance of 136 m (147 yds) during which it lost only 10-12 m (32.5-39 ft) in height.

Colugos have an unusual skull that possesses many primitive features. The teeth are also unique in that some of them are shaped like small combs: their function remains uncertain, though they may be used in grooming or gnawing.

Profile

Length: 38-42 cm (15.2-16.8 in), with a tail of 22-27 cm (8.8-10.8 in).
Weight: 1.0-1.75 kg (2.2-3.9 lb).
Distribution: Southeast Asia and adjacent islands of East Indies.
Habitat: Forest.
Breeding: Single young born in February-March.
Diet: Fruit, flowers, leaves.

Savi's Pygmy Shrew

The smallest non-flying mammal in the world

Barely 35 mm (1.4 in) long and weighing less than 2 g (0.1 oz), the pygmy shrew ranks as the real Tom Thumb of the mammal world.

Despite its diminutive size, Savi's Pygmy Shrew (Suncus etruscus), also known as the Etruscan Shrew, belongs to the genus that also contains the largest of the true shrews.

Constantly on the go when active, it keeps up a constant shrill chatter the function of which remains obscure (unclear). Though usually to be found scurrying about in the grass, it has been known to jump distances of 20 cm (8 in) - more than four times its own body length - to seize grasshoppers and spiders with a rapid snatch.

The pygmy shrew is so small it can even creep into the holes made by earthworms!

Profile

Length: 35-48 mm (1.4-2.0 in), with a 25-30 mm (about 1 in) tail.
Weight: 2 g (0.1 oz).
Distribution: Mediterranean area, eastward into Asia as far as Malaya and southward into Africa as far as the Cape.
Habitat: Grasslands.
Diet: Insects.

Red Bat

The world's hardiest flying mammal

When hibernating in winter, it can withstand its body tissues freezing into ice at temperatures as low as - 26 degrees C (-15 degrees F) without suffering any serious ill effects.

One of about a dozen species of red (or 'hoary') bats, the Red Bat (Lasiurus borealis) is a member of the most widely distributed group of bats in the New World.

Red Bats roost singly or in small groups in trees and shrubs, where they are well disguised against the tree-trunk. Their deep red colour gives them an effective camouflage which functions especially well during the autumn season, when they can easily be mistaken for dead leaves.

In fact, when disturbed at roost, they will sway gently from side to side in just the way a dead leaf does. Red Bats are particularly strong fliers, being able to outfly any other bat. The female will often fly while carrying two or three infants clinging to her fur, a load that can easily exceed her own body weight.

Populations living in Canada and the northern USA migrate southwards during the winter, some travelling as much as 2000 km (1250 miles) to spend the winter in northern Mexico.

The Red Bat is, nonetheless, well adapted to cope with the low temperatures that populations in the northern parts of the winter range experience. They are the most heavily furred, have the lowest heart rate at low temperatures, and have the highest red blood-cell count of any bat.

When they do go into hibernation, they curl up into a ball so as to minimise the area exposed to the cold.

Profile

Length: 50-90 mm (2.0-3.6 in), with a tail of 40-75 mm (1.6-3.0 in).
Weight: 6-30 g (0.2-1.0 oz).
Distribution: Throughout North America and the Caribbean.
Habitat: Any well-wooded areas.
Breeding: A single litter of 2-4 young produced in May-July.
Diet: Insects captured in flight.

Notes: The only bat to have more than 2 young in a litter.

Courtesy: Remarkable Animals