Tag: animals

A Few Things About Sloths Everybody Should Know

by Anupum Pant

A few days back, on 20th October, Sloth Day was celebrated all around the world. You’d be thinking, what is so good about these strange animals, that makes people have a special day around them. Well, in that case, you need to read this.

What are these creatures?

Sloths are slow animals that make even cows look extremely active. They are so slow that they are almost stationary and algae grows on their hair. Most of their life is spent on trees hanging upside down. They hang on trees to protect themselves from the predators on the ground. Their bodies are so well engineered to stay inverted that the hair on their bodies, is oriented in the opposite direction – growing from stomach to back (This helps them to stay dry by draining water easily). Even dead sloths have been know to retain their grip and remain suspended after death. They come down only around once a week to excrete. They eat, sleep, travel, find partners, mate, give birth and even raise young ones in the canopies.

Although sloths might seem gross, creepy and unseemly, they really aren’t that bad. Sloths are sweet looking [1] [2] [3] animals (especially their babies, they are adorable) who can also swim efficiently and move wisely. We can definitely learn a lot from them.

Their diet is unbelievable

Sloths eat only leaves throughout their lives. They chew leaves slowly like cows to extract whatever nutrients they can. Sloth intestines are also adapted to extract the maximum out of their poor quality food, they are unusually long. They often like to shift to a different kind of leaf after a day or two. This balances their nutrient intake. Humans couldn’t possibly survive on a leafy salad diet for a very long time.

To save energy, sloths drop the temperature of their bodies at night. Even their bodies have more bones than muscles to prevent wastage of energy through muscular movement. After the Orangutan they are the most energy efficient animals.

Other facts about them

Sloths have blunt teeth to chew leaves properly, have large claws to hang on to branches and inverted fur orientation (as also mentioned before). Another interesting thing about them is that they have remained physically un-evolved for a long time because they don’t really have to compete with anyone else for their diet.

Mutualisms

This is where the awesomeness of Sloths come in. Sloths are home to a several kinds of other organism (tiny ones living in their fur). These organism depend on sloths (hosts) for various things and in turn provide an advantage to their hosts. This is called mutualism.

  1. Algae + Sloth – Algae, for instance, uses the long grooves on sloth hair to grow with a secure footing. As a rent for this safe apartment, the algae gives them [sloths] a nice shade of green color to camouflage on trees. This and their still bodies make them virtually impossible to spot with the naked eye. The camouflage protects them from eagles.
  2. Bacteria + Sloth – Apart from the several other bacteria which live inside a sloth to digest the leafy diet, two kinds of Cyanobacteria live on sloth furs too. These bacteria also give sloths a nice gray hue which helps them in the same ways as above.
  3. The Sloth Moth – The Pyralidae Moth also live on Sloths. These feed on the algae which grows on the fur. In return for the good food, moths give them nothing. Yes, nothing. This is called Commensalism.
  4. Others – Similarly, various other organisms like flies, mites and three types of beetles are often found living in a Sloth. Up to 900 beetles have been found on a single Sloth!

There is so much more to write about these amazing little creatures who provide for so many other creatures too. I’ll keep it for the second part that I’ll write some other day. So the next time you see a Sloth crossing the road, carefully pick it up by holding its mid body and gently place it on a tree. Remember to use a glove/cloth.

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.