Category Nature Science & Wildlife

WHAT ARE STROMATOLITES?

Primitive life forms may have first appeared on Earth about 3800 million years ago. These bacteria lived in the oceans and built up solid mats of calcium carbonate, also known as lime. The deposits from the bacteria are known as stromatolites.

Stromatolites are living fossils and the oldest living lifeforms on our planet. The name derives from the Greek, stroma, meaning “mattress”, and lithos, meaning “rock”. Stromatolite literally means “layered rock”. The existence of these ancient rocks extends three-quarters of the way back to the origins of the Solar System.

With a citizen scientist’s understanding, stromatolites are stony structures built by colonies of microscopic photosynthesising organisms called cyanobacteria. As sediment layered in shallow water, bacteria grew over it, binding the sedimentary particles and building layer upon millimetre layer until the layers became mounds. Their empire-building brought with it their most important role in Earth’s history. They breathed. Using the sun to harness energy, they produced and built up the oxygen content of the Earth’s atmosphere to about 20%, giving the kiss of life to all that was to evolve.

Living stromatolites are found in only a few salty lagoons or bays on Earth. Western Australia is internationally significant for its variety of stromatolite sites, both living and fossilised. Fossils of the earliest known stromatolites, about 3.5 billion years old, are found about 1,000km north, near Marble Bar in the Pilbara region. With Earth an estimated 4.5 billion years old, it’s staggering to realise we can witness how the world looked at the dawn of time when the continents were forming. Before plants. Before dinosaurs. Before humans.

Credit: bbc.com

Picture credit: Google

WHAT IS THE TIMELINE OF LIFE ON EARTH?

Just as the day is divided into hours, minutes and seconds, geologists divide Earth’s history into time periods. The longest divisions are aeons, which are billions of years long; the shortest are chrons, a few thousand years long. In between come eras, periods, epochs and ages. Scientists divide the last 590 million years into three eras: the Palaeozoic (meaning ‘old life’), Mesozoic (‘middle life’), and Cenozoic (‘new life’).

Humans have only been a species in the most recent chapter of the history of Earth. The Earth was formed 4.6 billion years ago, when the sun in our solar system first formed, creating enough gravitational pull to spin planets into orbit. But how do scientists know how old the Earth is if humans weren’t around back when it was formed? When was life first formed on this planet? And what are the paths that life has taken so far over the course of that existence? This lesson will teach about the ages that make up the history of life on Earth, and explore the many changes and forms life has taken in its time on this planet.

Timeline of Geological Eras

The geological timeline of Earth is nearly identical to the history of life on Earth, apart from the Hadean Era. This is because the geological timeline, or the order of geological events, such as oceans forming, volcanoes erupting, how long deserts lasted, and tectonic plate movement, all happened in sequence with the life that has existed on this planet. The history of both life and the geological timeline is arranged within 5 subgroups, arranged from the largest span of time to the smallest: eons, eras, periods, epochs, and ages. To understand the timeline of life that has existed on Earth, it is important to understand how scientists determine the age of both rocks and the remnants of living things, otherwise known as fossils.

Because humans were not around 4.6 billion years ago to record the beginnings of our planet, scientists must rely on evidence from geological and fossil records in order to determine the relative age of both the planet and the life that exists here. Both the geological timeline and the age of life are determined in much the same way. Modern scientists rely on what is called radioactive dating to determine an accurate and precise age of both rocks and fossils. Radioactive dating measures the rate of decay of an element in a rock or in a fossil. Carbon-14 is typically used when dating fossils because all living things are carbon-based, and the flow of carbon can be tracked through the carbon cycle. For geological objects such as rocks and minerals, Rubidium-87 and Potassium-40 are often used. By knowing how long it takes for molecules in an object to decay, scientists can calculate when the object’s half-life is. The half-life of an object refers to the amount of time it would take for half of an amount of a substance to radioactively decay, or break down. If the half-life of an object is known, it is possible to calculate when the object was first created, when no decay is evident.

Credit: study.com

Picture credit: Google

What is the largest carnivorous marsupial?

The Tasmanian devil is the largest carnivorous marsupial, known for their high-pitched squeal and aggressive temperament. They have held this title for over 80 years. Specifically, these creatures weigh between 9 and 29 pounds. A Tasmanian Devil weighing 29 pounds is as heavy as three one-gallon cans of paint. These mammals range from 20 to 31 inches long. Picture two bowling pins lined up end to end and you have the length of a 31-inch Tasmanian Devil. This mammal’s tail is equal to half of its body length. These animals store fat in their tail to use for energy. So, if you see one of these animals with a thick tail, you know it’s healthy. Thanks to conservation efforts, they are being reintroduced to Australian mainland after a 3,000-year gap. Mother devils can give birth to 50 young ones at one go. However, very few survive.

A Tasmanian Devil is a small animal with short brown or black fur with a stripe of white hair across its chest. Some of these marsupials have patches of white hair near their dark tail. This marsupial’s front legs are longer than its back ones. They have dark eyes and small mouselike ears. These animals have excellent sight and hearing allowing them to track down prey at night.

They are known for their very strong jaws. In fact, this marsupial’s jaws have a bite force of 94 pounds. That strong bite force allows them to easily consume the meat, hair, bones, and organs of the dead animals they find. Some scientists refer to Tasmanian Devils as environmental vacuums because they clean up the carcasses they find in their habitat.

Credit : A-Z-Animals

Picture Credit : Google 

Can peacocks predict rain?

Have you watched a peacock dance? It is a beautiful sight to behold. We have heard people say that a peacock dance is an indicator of rain. How true is this? Sadly, the reality is not as cool as it sounds. The male of the Indian peafowl species is called the peacock. (The female is called the peahen and the offspring, the peachick). The stunning pattern on their metallic blue-green covert feathers (called a train), and the eye spots are something unique to the Asiatic species. (The Congo peacocks do not have the train nor the eyespots).

A peacock opens its train and dances to attract a peahen. It is part of the courtship ritual, where the male fans his tail displaying the eyespots. Peacocks moult (shed) their train at the end of every breeding season. So, what is the link between rain and their dance? Peafowls breed during the wet or rainy season. Hence, it is only a coincidence if you watched a peacock dance and you witnessed a rain soon after.

Picture Credit : Google 

What do we know about spectral bats?

The closest relative of the big-eared woolly bat, the spectral bat is a large, carnivorous leaf-nosed bat. It is usually found in Mexico, Central America, and South America.

Known as the great false vampire bat or Linnaeus’s false vampire bat, the spectral bat is in fact the largest carnivorous bat. It has a robust skull and teeth which makes it easy for it to deliver a powerful bite to kill its prey.

What it feeds on depends on the availability of prey. It usually feeds on birds, rodents, and other species of bat. It also eats some insects like beetles. The caloric needs of a spectral bat are high and it has to feed often.

The overall population of the spectral bat is decreasing. In 2018, it was declared ‘near threatened’ by the IUCN.

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What are the characteristics of the big-eared woolly bat?

Big-eared woolly bats are very large predatory bats with diverse feeding habits. They are known to eat geckos and even fruit. They are primarily carnivorous and insectivorous, though.

Big-eared woolly bats can take preys that weigh around 70 grams, but they usually consume smaller ones. They feed primarily on small arthropods and small vertebrates, including beetles, moths, small mammals, birds and even other bat species. But they usually do not consume the catch until they have returned to their roost in their heads-down position.

These bats usually fly slowly, partially because of their large size; their body mass typically ranges from 75 to 96 grams. Big-eared woolly bats live in colonies that are usually small. Even if they live in ground, their colonies are usually small. A typical colony consists of up to seven bats, usually a male-female adult pair and their offspring.

Picture Credit : Google