biology – Page 6 – Awesci

Ming – A 507 Year Old Organism Killed By Scientists

By Anupum Pant

A few years before Leonardo da Vinci started painting the Mona Lisa, somewhere deep in the ocean, in the year 1499, a clam was born. When it stepped into this world, it was also the period of Ming Dynasty in China, so several years later the clam was named ‘Ming’ (Scientific name: Arctica islandica) by scientists. Ming was the 507 year old organism that unfortunately got killed.

Like crocodiles, clams are also one of those biologically immortal organisms. This one lived on for 507 years till the year 2006, when it was discovered by a group of researchers in deep oceans. Unaware of its age, researchers stored it like all the other 200 clams they had gathered, using refrigeration, which killed it (and the others). It was an unfortunate accident; definitely not intended in any way.

World record: Ming the clam was recorded as the oldest individual animal ever discovered. The record mentions “Individual” because often colonies are recorded to live for really long times. By those measures, this clam would have stood nowhere in comparison. For example the deep-sea black and gold corals 2700 years old have been found. But, scientists are pretty sure that there are older individual organisms [than Ming] still living out there, waiting to be discovered.

Why do they live so long?

Their genes, extremely slow oxygen intake and very slow metabolism are some of the known factors that enable these clams to live for centuries. Their age is measured accurately by using Radiocarbon dating.

The Rings: But more importantly these clams have rings on their shells. These rings are like our fingerprints, unique for each clam. The number of rings on the shell also gives a pretty accurate estimate of their ages; like rings on a tree stump help us to find the age of a tree. Initially, a few researchers, using these rings, wrongly estimated the age of Ming to be around 400 years. It was corrected later by others.

The oxygen isotopes present on the rings can be detected too. These measurements give scientists a useful insight about the climate changes that must have happened over the years.

Author’s Note: This is the 50th post by me here which marks a 50 day anniversary. By now, I’ve become a happy blogger with more than 12K views already. Thanks all. Do take some time to check out the archives.

Crocodiles Do Not Die

By Anupum Pant

Technically some animals like Alligators, Flounders and Crocodiles do not die. Instead of aging biologically, they just keep on growing physically. But why do Crocodiles all over the world keep on dying?

Senescence

In reality, we do see them dying. So, it would be right to say that they have the potential to live forever. To understand this we’ll have to first look at the term – Senescence.

Senescence is a term used to indicate gradual deterioration of the body with age. In simpler words, you could call it ‘aging’. Specifically, weakening of muscles, lowering mobility, poor sensory acuity and age-related diseases are signs of an animal showing senescence. Most animals exhibit Senescence. So, as we get older our deteriorated life parameters increase our risk of dying – Humans exhibit Senescence; Crocodiles do not.

Negligible Senescence

But, here on Earth, living with us, are a few species that exhibit Negligible Senescence. That means, they show almost no signs of aging, or they are ‘biologically immortal’. Animals like these only die due to diseases, accidents or predators.

In animals, sea urchins, lobsters, clams and hydras are some examples. Vertebrates like a few Tortoises, Turtles, Crocodiles, Alligators, Rougheye rock fish and Flounders have been not observed to have aged biologically. That is the reason we had a 255 year old tortoise in the Kolkata zoo till the year 2006.

Among trees, probably the best example for an individual would be one Methuselah tree, which has been living for 4800 years. Its exact whereabouts are kept a secret to save it from us. On the other hand, a colony of a single tree has been estimated to be around 80,000 years old. It is also the heaviest known organism.

Side note: Tardigrades survive extreme conditions using a technique called cryptobiosis. They can die and literally come back to life.

Back to Crocs

Crocodiles have no such thing as old age. A 7-year-old crocodile is as good as a 70-year-old one in terms of agility and other life parameters. Aging has no effect on them. Although they can’t die of natural aging, they also can’t live forever. Nature has a way of killing them. The way they die is out of starvation or if they contract a disease.

They keep growing throughout their lifespan and they require more and more food. So, as they keep getting older they need a lot more food. When that amount of food is unavailable, they die from starvation. That is the reason we don’t see 1000 year old crocodiles that are 50 feet long. Still, see what this hunter shot in Australia in the year 1957 – It was an 8.1 m (28 feet) long crocodile!

Even if making human beings biologically immortal is an extremely controversial area, it doesn’t stop scientists. Scientists love to study organisms that exhibit negligible senescence because they’d love to find out a way to halt the aging process in humans by mimicking their gene structures. Probably, in the near future, we’ll find a way to demonstrate limitless Telomere regenerative capacity like Planarian Flatworms in humans.

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Miniature Sealed Self-Sustaining Ecosystem

By Anupum Pant

53 years ago, David Latimer (80) from Surrey planted an indoor Spiderwort in a huge glass globular bottle. He has watered it just once, in the year 1972. Since then, this self-sustaining ecosystem, has been sealed away from the outside world for around 40 years. In spite of being sealed away like that, the plant has grown very well in its own miniature ecosystem [Picture]. The only regular external energy it has received has been in the form of light. [more about this self-sustaining ecosystem and how it works]
The EcoSphere or the Original EcoSphere takes it to the next level by introducing a shrimp in a similar setting. Like David Latimer’s bottle, this is also a self-sustaining ecosystem consisting of algae, bacteria and shrimp. The company that sells these things says that the shrimps would last for just around 10 years. Although, they also claim of 25-year-old spheres with living shrimps.
10 years is little as compared to the ecosystem discussed in the first point. But we are talking about a pet living in a completely sealed space for 10 years, without demanding food, change of water or an appointment with the vet. For these little creatures it is probably a safe haven away from the dirty oil slicked oceans and predators; or probably just a prison.

These little biospheres are a far simpler and smaller versions of our big worlds. We are like the shrimp and the trees, our algae. This diagram explains in a simple way, how these artificial, extremely simplified versions of Earth work – [Diagram]

The shrimp and algae biospheres were discovered by two scientists, the late Dr. Joe Hanson and the late Dr. Clair Folsome. Later, NASA became interested in these systems. There got interested because:

This tiny model of the Earth could add information to NASA’s Mission to Planet Earth program for studying Earth’s biosphere.
It could help NASA’s research on human life support systems directed toward the construction of space stations for exploring our solar system.

Make it for yourself: Make magazine published a detailed DIY guide on how to create these living biospheres at home. [Link]
Carl Sagan’s Review of these biospheres: The World Arrived in The Mail.

Random Foliage Fact:

The world’s smallest park is located in the median strip of SW Naito Parkway, approaching esplanade along the Willamette River near SW Taylor Street in downtown Portland, Oregon, United States. Mill Ends Park, a 2 ft is a circular park, has held a place in the Guinness book of Records since 1971. It isn’t a park you can send your children to. – [Wikipedia]

Human Echolocation – Seeing With Your Ears

By Anupum Pant

Bats can see, but Daniel Kish can’t. Due to Retinal Cancer (Retinoblastoma), Daniel has been completely blind since the age of 13 months. To save his life, both his eyes had to be removed at a young age. But, even with no eyes, he can see. He sees with his ears. People call him the real-life batman.

What? When Daniel was young, he started making a clicking sound with his tongue to understand his environment. Little did he know, at a young age, he had mastered Echolocation – A technique used by dolphins, and bats to navigate when there is no light. At the age of 11, only when a friend told him about Echolocation, did he realize what he was really doing.

How? By listening to the reflected clicking sound, Daniel is able to map the shape, dimension, depth and density of objects in his brain. Like we use light to see, he uses sound to create a 3D map in his brain. He has trained his visual cortex to process non-visual information. With this ability he is able to ride a bicycle around, effortlessly. Think about riding with your eyes closed. He does it everyday.

According to him, what he does isn’t rocket science. He thinks every one, if trained well, can do it. With a concern for blind people around the world who aren’t encouraged to use echolocation to move around, he started an organization where he teaches people how to do it. You can watch his TED talk here. [video]

Side note: In a Tamil movie, Taandavam, he was the one who taught Shiva to move around using echolocation.

If you think Daniel’s ability doesn’t talk enough about the amazing human brain. This video of David Eagleman talking about how our brain perceives the world, will probably make you appreciate it [the brain] more. Watch it till the end where he talks about these plug-in-brain devices.
In short, brain can learn to interpret various kinds of signals to produce an image.

[read more]

Sharks Are Not So Bad After All

By Anupum Pant

Sharks have been on earth for millions of years more than we have been here. Also, they haven’t changed much since a long time. The kind of sharks we see today, were the same sharks that existed 350 million years ago.

That means, modern sharks have lived happily for millions of years without eating humans. Even today, they aren’t very keen on killing us for food. They simply aren’t designed (or haven’t evolved) to do that. Humans were never a part of their normal diet. Instead, they normally feed on small fish. While a few other species of sharks may eat seals, sea lions and other mammals too. In fact, they can go on for months without food.

Funny as it may sound, sharks are scared of humans. When a shark sees a human in water, it gets confused and scared. It goes near to check, and this usually results in an accidental bite. They don’t kill humans out of aggression. With 15 rows of razor sharp teeth on each jaw, even their gentle bites may kill a person. About only 20 out of 300 species of sharks are reported to have been involved in accidents with human beings. About 100 such accidents occur every year.

Not being insensitive about human deaths: Can you estimate how many people do sharks kill every year? The answer is 10. Ten people, on an average are killed by shark bites every year. That is about 1/15 th of number of people killed by coconuts every year*
*Note: “150 people are killed by coconuts every year”, is a popular urban legend. The coconut death figure is a crude estimate or just a figure pulled out of thin air.

Nevertheless, the number of people killed by sharks every year is very very less (again, even a single human death isn’t really ‘less’). I’d rather not use statistics to prove my point. [image]

Why are sharks scared of us? … Why shouldn’t they be?
We kill about 100 million sharks every year. That is such a huge number when compared to number of people sharks kill every year. Again, statistics could be deceiving here. But we do get an idea. There is a massive difference in the number.
Why? Humans catch sharks for their meat, internal organs and skin, to make products such as shark fin soup, lubricants, and leather etc. Some times, fins are cut and live sharks are thrown back into the sea, crippled. This eventually kills them due to excessive bleeding or other obvious reasons.

It is ironically that we move into their natural habitat and in turn blame sharks for destroying our boats, surf boards. Moreover, we are shocked to hear about reports of shark attacks on humans. Shouldn’t it be the other way round? We should stop looking at sharks as if they are the monsters; we are. At the same time, that doesn’t mean you should risk your life by going in shark waters to give it a high-five.

Random Science Fact:

Only 14% of the Earth’s species are known to us. 75% of all the species on Earth will be gone within the next 300 years. Think about those species which will go extinct while we are here, and we’ll never know about them.

Elephant Bird – The Heaviest Bird Ever

By Anupum Pant

Scientific Name: Aepyornis maximus

No, it isn’t about a bird with a trunk or tusks. Weighing almost half a ton, the aptly named, elephant bird of Madagascar, was the heaviest bird to have ever existed on earth. It looked like an Ostrich on steroids and of course it was a flightless bird. The number 3 bird in this picture is an illustration of the Elephant bird (around 10 feet in height) [image]

Note: Although we say that it was the heaviest bird to have ever existed, we can only say that because we haven’t been able to find any traces of a larger bird yet.

Interestingly, it wasn’t something that belonged to the Dinosaur era. It went extinct recently, around the 17th or 18th century, probably due to humans hunting it for food. Since cameras did not exist at that time, only written accounts of its sighting have been found.

As logic dictates, a huge bird would lay huge eggs. So, with a volume of about 180 to 250 times that of a chicken egg, measuring about 1 feet in height, its eggs were the largest laid eggs ever; larger than human heads. The shells could hold around 11 liters of liquid. Its eggs were said to have fed whole families. Some of them have been preserved – Some are being auctioned and some are available in museums. National Geographic Society in Washington holds a specimen that has the skeleton of an unborn Elephant bird.

Axolotl – A Walking Fish That can Regenerate Limbs

By Anupum Pant

If you are looking at an Axolotl for the first time, it will confuse you. With an oddly shaped body that resembles both a catfish and a salamander, you’ll wonder if it lives in water or on land. [Image]

What is it?

A fish? Axolotl, commonly known as the Mexican Walking Fish, isn’t actually a fish. It is an amphibian, which means it has both lungs and gills. They almost never come out of water, hold their breath and take in oxygen using their gills (those three pairs of parts coming out at the back of its head are the gills). They can hold their breath for a year, beat that Mr. David Blaine.

Or Salamanders? They are closely related to salamanders and interestingly the adult Axolotls look like baby Salamanders. They have long abandoned the usual amphibian-transformation from a larva stage to an adult. Unlike Salamanders, they don’t transform into adults that can live outside water. They stay in water and walk around on the water-bed.

However, strange species of Axolotl was once delivered to a zoologist Auguste Duméril, which had somehow transformed like salamanders and would happily come out of water. But this transformation (metamorphosis) shortened their life span. Later it was found that this process can be artificially triggered by injecting iodine. (Do NOT try this at home)

As pets: Today, these animals are fairly common and are used as exotic pets all around the world. Especially in Japan, people love to have them in their aquariums.

Side note: Like several other Pokémon based on real animals, Whooper and Mudkip were actually based on Axolotls.

Regenerative Powers

Besides having the ability to walk underwater and its unusual appearance, there is something that is much more interesting about them. Unlike, almost any other vertebrate, they have the power to regenerate various cells. Not just cells, Axolotls can regenerate complete body parts – limbs, gills, eyes, kidneys, even large portions of its liver and its heart muscle. Even portions of its spine and brain can be regenerated. They are able to grow back a severed limb in span of few months. This is the reason scientists love these creatures and conduct a number of studies on them every year.

Tardigrades – Toughest Creatures on Earth

By Anupum Pant

So, if you think elephants or cockroaches are tough, that could be because you probably haven’t heard about these amazing creatures called Tardigrades (picture).

What are Tardigrades?

Tardigrades, also known as moss piglets or waterbears, are oddly cute little animals that live in water and feed on moss. Their size ranges from 0.1 mm to 1.5 mm and they have eight legs (they walk like bears). The most extreme thing about these extremophiles is that they can survive almost anything (actually, they kind of die for a while with an option to come back to life later). Here is a list of things Tardigrades can survive. They can:

Survive without water and food for 10 years.
Waddle away in the vacuüm of space (for 10 days & get exposed UV radiation), come back and walk around as if nothing happened.
Survive 1000 times more radiation that would kill an elephant.
Live through extremely low temperatures (almost absolute zero) or high temperatures (~150 degree Centigrade)
Repair their own DNA after getting exposed to lethal amounts of radiation.
Survive pressures of about 300 Jumbo jets stacked on a person. (6 times more than the deepest ocean trenches)

Scientists love them

People at NASA and the European Space Agency love doing tests on them because they think, Tardigrades can help them understand the origin of life on earth (probably by supporting Panspermia). Also, scientists want to find out more about their extreme capabilities. If you ask them, if these things are aliens, they’ll tell you – “Probably not”

[Learn more about Tardigrades]

Why Do Bad Eggs Float?

By Anupum Pant

Instead of cracking up an egg which has been stored for a long time, to end up disgusted by the ‘rotten egg smell’, or the smell of a gas called Hydrogen Sulfide, a simple and a fairly well known way to check if an egg has gone bad, is to drop it in a glass of water and see if it floats. I found out about this first, from an article written at Frugal Living, and spent some time to confirm its claims – Bad eggs float.
If you take my word for it (you should!), it really does work. The article describes this three-point test to find out if an egg is good to eat.

If the egg sinks and lies on its side, it is a fresh one. It is good enough to be eaten.
If it sinks and stands up on a point, or is at an angle, it is good enough. You can still use it up for making hard-cooked eggs or bake it.
But, if an egg floats, it needs to be discarded.

Why does this happen?

To understand, you’ll have to think of a chick – a young chicken.

Poor Chicks: Before chickens come out of the egg, they develop lungs and need oxygen to breath. Sitting inside a sealed egg, with no cords attached, for the chick to survive, oxygen has to come in from somewhere. For that, let us look inside.

Egg Science: The outer shell of an egg has two membranes under it. When an egg is laid, it is warm and starts cooling which contracts the inner part of the egg more than the shell and pulls the two membranes apart. As a result, air gets trapped in between the membranes (not enough air initially for it to float).

How does the air come in? The shell of an egg isn’t as simple as it looks. It has about 7000 tiny pores in that shell which let the air pass in and let the carbon dioxide pass out of it. This is how the chick breathes. And the reason, eggs boiled in colored water during Easter, get colored from the inside.

So, as there are pores present in the shell, bacteria enter the egg and start decaying the biological matter inside. This produces a smelly gas (and other gases too), Hydrogen Sulfide (also present in smelly farts). The gases from this decomposition, and the air from outside, keep increasing in volume as time passes.

Corollary: This is exactly what explains these floating bad eggs – Greater the amount of gas inside, older is the egg and the better it floats in water.

Side note: Egg shells and the two membranes inside have the ability to stop the invasion of micro-organisms and bacteria, but over time bacteria manage to enter.

A Bat’s Inverted Sleep Position

by Anupum Pant

I have written about sloths in the past. In that post, we appreciated the way their bodies are engineered to stay inverted for most of their lives. It turns out, a bat’s body is designed (rather evolved) in a similar way, which enables them to relax and sleep upside down. In this post, I would like to discuss – why did they evolve this way and how do they do it?

If you are interested to know more about bats, you will definitely like this post from the archives. [Bats can See]

How can bats manage to sleep like this?

Humans sleep in a horizontal position, cows sleep with their eyes open, horses sleep in a standing position, and of course, bats sleep in an inverted position. What makes an animal sleep in the position they do, is basically their anatomy – the way their bodies are designed. While sleeping upside down might seem as an anomalous behavior to us, it is a normal position for the bat’s body. Like we don’t exert energy when we are lying down, bats’ bodies don’t consume extra energy for hanging down like that.

Firstly, a bat’s claw is like a hook. A better way to understand why this helps is, to look at a converse behavior – the way a human hand works. We use up energy to contract tens of muscles and make up a hook with our fingers; this is not a normal state of our hand. Also, our relaxed hands are open where we don’t exert any energy and we sleep with our hands in that position. A bat’s claws are designed in a completely inverse fashion; they are hooked in the normal position. They don’t take up energy to make them into hooks, they are like that. And they sleep like that – which enables them to hang without using energy.
So, unlike our hands, a bats’ closed fist is their relaxed position. They have to contract tendons and use energy to open them up. This anomalous talon design allows them to hang in a relaxed position.

Secondly, unlike every other bird, a bat can’t take off from an upright position, or from the ground. They have to be inverted to start flying. This is because they have relatively weaker wings which can’t make them fly from a stationary position. Think of an X-51A Waverider, which has to be carried on a B-52 plane and dropped down to start a flight. They drop down for a very small amount of time and beat their wings vigorously to start a flight. Since, they have to wake up inverted to go flying and catch a meal, they go to sleep like that.

Why did they evolve this way?

They’ve evolved this way to simply stay away from the predators:

By hiding up in a place where not many predators would look – under a bridge, roof of the cave and dark tree canopies. Also, at places like these, they don’t have to compete with other birds for a place.
And by escaping quickly in case of an attack by attaining instant flight [see above].

The Purpose of Sleep – Theories

by Anupum Pant

Did you know?

You can live longer without food than you can live without sleep.
On an average, a person sleeps for 1/3rd of his life. That means if you are 30 years old, you’ve slept for 10 years already.
The world record for the longest span remaining awake is 11 days. The record was set by 17-year-old Randy Gardner in 1964 when he was awake for 264 hours and 12 minutes. (Don’t try this)
If it takes you less than five minutes to fall asleep then very likely you are sleep deprived. It should take about 10 minutes normally.
You can lose up to 2 grams every minute while sleeping. That comes to about a lost Kilogram at night.

What is Sleep?

Everybody sleeps. On an average, everyday, a bat sleeps for 15 hours while just 3 hours are enough for a Horse to feel rested [How much do animals sleep – chart]. Dolphins can sleep with half of their brains active and even the smallest of worms need sleep. But, till date, scientists haven’t been able to reach a consensus on why we actually do it?

Sleep can be understood as a life sustaining activity. It can be compared to another of our important activity – eating. These strongest of the human urges – eating and sleeping – serve a nearly common purpose – quell the urges; just as eating relieves hunger, sleeping relives sleepiness.

While it is true that we may have not been able to spot the primary purpose of sleep, years of research hasn’t gone wasted. With time, we have learnt a lot more about sleep than we used to know 50 years back. There have been hundreds of practical and impractical theories on why we sleep. I’ve mentioned a few of the realistic ones here.

Purpose of Sleep – Theories

Inactivity Theory:

According to this old theory, sleep evolved out of the need to be safe. It suggests that inactivity at night is an adaptation that serves as a survival mechanism. It functions as an activity which would keep an animal safe during the time it is most vulnerable e.g. Humans are vulnerable at night because they don’t see well in dark.

This theory is easily countered using the argument: Being conscious and still, is much better way to stay safe than lying unconscious and still.

Energy Conversation Theory:

It suggests, the main function of sleep is to reduce the demand and consumption rate of energy at times when searching for food isn’t an efficient option. Some believe, that this theory is a part of the inactivity theory. But, unlike the inactivity theory, this theory has been bolstered by various experiments which prove that the consumption of energy is reduced when an organism sleeps.

Restorative theory:

It explains sleep as an opportunity for a body to rejuvenate in terms of muscles, tissues, proteins, cells and growth hormones. Also, during sleep, the body clears an accumulated molecule called adenosine from the system, and makes us feel alert when we wake.

A recent study also seems to support the restorative theory in a fresh manner. It says, brain accumulates toxins [like beta amyloid] while it is awake. The concentration of such toxins keeps increasing during waking state. The study observed an increased activity of spinal fluid being pumped into the brain in rodents (hasn’t been studied on humans yet). This spinal fluid functions as a medium to pump out toxins from the brain. This theory could be a breakthrough in the study of causes and prevention of Alzheimer’s as it is known that toxins like beta amyloid cause the disease in humans [How beta amyloid causes Alzheimer’s].

Brain Plasticity Theory:

According to this, sleep plays a critical role in brain development. Infants (age when the brain develops the most), for example, sleep for about 13 – 14 hours every day. On the other hand, the poor ability to learn and perform tasks due to the lack of sleep explains the role of sleep in adults. Since, It has been proven that brain is highly active during sleep, this theory remains the most plausible one in being able to state one of the functions of sleep.