Category Animal World

HOW LONG AGO DID LIFE APPEAR?

The first signs of life – probably bacteria – appeared nearly four billion years ago. But animals with shells and bones did not appear until less than 600 million years ago – these were the first living things preserved as fossils. It is mainly with the help of such fossils that geologists have built up a picture of Earth’s history since then. Very little is known about the four billion years before this, called the Precambrian period, which makes up more than 85 per cent of Earth’s history.

The evidence is overwhelming that all life on Earth has evolved from common ancestors in an unbroken chain since its origin. All life tends to increase: more organisms are conceived, born, hatched, germinated from seed, sprouted from spores, or produced by cell division (or other means) than can possibly survive. Each organism so produced varies, however little, in some measurable way from its relatives. In any given environment at any given time, those variants best suited to that environment  will tend to leave more offspring than the others. Offspring resemble their ancestors. Variant organisms will leave offspring like themselves. Therefore, organisms will diverge from their ancestors with time. The term natural selection is shorthand for saying that all organisms do not survive to leave offspring with the same probability. Those alive today have been selected relative to similar ones that never survived or procreated. All organisms on Earth today are equally evolved since all share the same ancient original ancestors who faced myriad threats to their survival. All have persisted since roughly 3.7 billion to 3.5 billion years ago during the Archean Eon (4 billion to 2.5 billion years ago), products of the great evolutionary process with its identical molecular biological bases. Because the environment of Earth is so varied, the particular details of any organism’s evolutionary history differ from those of another species in spite of chemical similarities.

Credit: Britannica

Picture credit: Google

WHAT IS A FOSSIL?

Fossil, remnant, impression, or trace of an animal or plant of a past geologic age that has been preserved in Earth’s crust. The complex of data recorded in fossils worldwide—known as the fossil record — is the primary source of information about the history of life on Earth.

Only a small fraction of ancient organisms are preserved as fossils, and usually only organisms that have a solid and resistant skeleton are readily preserved. Most major groups of invertebrate animals have a calcareous skeleton or shell (e.g., corals, mollusks, brachiopods, bryozoans). Other forms have shells of calcium phosphate (which also occurs in the bones of vertebrates), or silicon dioxide. A shell or bone that is buried quickly after deposition may retain these organic tissues, though they become petrified (converted to a stony substance) over time. Unaltered hard parts, such as the shells of clams or brachiopods, are relatively common in sedimentary rocks, some of great age.

The hard parts of organisms that become buried in sediment may be subject to a variety of other changes during their conversion to solid rock, however. Solutions may fill the interstices, or pores, of the shell or bone with calcium carbonate or other mineral salts and thus fossilize the remains, in a process known as permineralization. In other cases there may be a total replacement of the original skeletal material by other mineral matter, a process known as mineralization, or replacement. In still other cases, circulating acid solutions may dissolve the original shell but leave a cavity corresponding to it, and circulating calcareous or siliceous solutions may then deposit a new matrix in the cavity, thus creating a new impression of the original shell.

Fossils of hard and soft parts that are too small to be observed by the naked eye are called microfossils. Some fossils are completely devoid of plant and animal parts but show evidence of an organism’s activities. Such traces of organisms, which are appropriately known as “trace fossils”, include tracks or trails, preserved waste products, and borings.

Credit: Britannica

Picture credit: Google

How are baby elephants similar to human babies?

Baby elephants suck their trucks just like human babies suck their thumbs. And they do it for the same reason – comfort. Trunk sucking also helps young elephants master the use of their trunks for feeding.

Aside from the comfort it provides, trunk sucking helps an elephant calf learn how to use and control this lengthy appendage. With more than 50,000 individual muscles in the trunk, you can imagine how complicated it is to get it to do what you want it to do at any given time. Sucking on the trunk helps a young elephant learn how to control and manipulate the muscles in the trunk so that it can fine-tune its use.

Elephants also suck their trunks as a means of advanced “smelling.” They can taste the pheromones of other elephants by touching their trunks to urine or feces and then popping the trunk in their mouths to get a closer whiff.

While trunk sucking is primarily a mannerism found in young elephants, older elephants—even mature bulls—have been seen sucking their trunks when they are nervous or upset.

Credit :  Tree Hugger

Picture Credit : Google 

WHAT IS A WOOLLY MAMMOTH?

Woolly mammoths were closely related to today’s Asian elephants. They looked a lot like their modern cousins, except for one major difference. They were covered in a thick coat of brown hair to keep them warm in their home on the frigid Arctic plains. They even had fur-lined ears.

Their large, curved tusks may have been used for fighting. They also may have been used as a digging tool for foraging meals of shrubs, grasses, roots and other small plants from under the snow.

Though woolly mammoths went extinct around 10,000 years ago, humans know quite a bit about them because of where they lived. The permafrost of the Arctic preserved many woolly mammoth bodies almost intact. When the ground around riverbanks and streams erodes, it often reveals the corpse of a long-dead mammoth that looks much like it did when it died.

Woolly mammoths were around 13 feet (4 meters) tall and weighed around 6 tons (5.44 metric tons), according to the International Union for Conservation of Nature (IUCN). Some of the hairs on woolly mammoths could reach up to 3 feet (1 m) long, according to National Geographic.

Credit: Live Science

Picture credit: Google

What are the fun facts about Tamanduas?

Tamanduas, also called lesser anteaters, are smaller than their giant anteater relatives. They live in a variety of habitats – including tropical forests, scrub grasslands and wetlands – and are often found near streams and rivers.

A tamandua’s sticky tongue is the perfect bug catcher. At nearly 16 inches long, it can easily scour the narrow tunnels of termite mounds and ant colonies. All anteaters, including tamanduas, belong to the suborder Vermilingua, meaning “worm-tongue.”

They can eat about 9,000 insects a day. Tamanduas tear into logs with their strong claws and use their tongues to slurp up insects. Though they are anteaters, they also chow down on termites, mealworms, bees (and their honey), and even the occasional fruit. Tamanduas’ mouths only open to about the width of a pencil eraser and they have no teeth, so a muscular gizzard in their stomach helps them digest their meals. Tamanduas are arboreal, meaning they spend most of their time in trees. Their prehensile tails can grasp onto branches, helping them maintain balance as they climb high above the ground. The underside of a tamandua’s tail has no fur, which helps it grip branches more securely.

Tamanduas are amazing animals, but they require specialized care and should never be kept as pets. It is against the law to keep a tamandua without a license in some areas, and tamanduas often die while being illegally transported for the pet trade.

Tamanduas are hunted by harpy eagles and big cats, such as ocelots and jaguars, but they won’t go down without a fight. How do tamanduas protect themselves? Big claws and muscular forearms help them fend off attacks. They also deter predators by hissing and releasing a stinky odor from their anal glands.

Tamanduas have huge claws that prevent them from walking flat-footed on the ground, so they walk on the sides of their paws instead. Though tamanduas tend to stick to dry land, they have occasionally been known to swim.

Credit : Smithsonian voices 

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