Earth's toughest animal?

What if I say there is an animal who is known to be the toughest animal on earth and have survived all five mass extinctions, sounds interesting right?

Tardigrades {phylum- Tardigrada} are known to be nearly immortal and are capable of living in extreme conditions. They are microscopic animals, also known as water bears or moss piglets. 

This phylum was discovered in 1773 by German scientist, Johann August Ephraim Goeze. He named them 'little water bears' due to their appearance like a bear. Later on, in 1776, an Italian biologist, Lazzaro Spallanzani named them 'tardigrades' which means slow steeper. This phylum consists of thousand known species as per ITIS{Integrated Taxonomic Information System}. 

 Johann August Ephraim Goeze

                                      

Lazzaro Spallanzani

Their body consists of a head, three body segments each with a pair of legs, and a caudal segment with 4 pairs of legs.  Their size range varies from 0.05mm to 1.2mm. They can be majorly found in a moist environment or at the bottom of the lake sticking to the pieces of mosses. They suck juices from algae, lichens, and moss for their survival.

 So why do we call them the toughest animal on earth? 

It's been claimed that tardigrades have successfully been able to withstand the temperature as cold as -328℉ {-200℃} or as hot as 300℉ {148.9℃}. these animals have been living on earth for over 500 million years and have survived five mass extinctions. Also, they can bear a pressure up to six times of pressure at the bottom of the sea and about 1000 times more radiation than humans. They have successfully survived the vacuum space when scientists took them to the moon for 10 days.

How do they live in an extreme environment?

In extreme conditions, they survive by going into an almost death-like state called Cryptobiosis {a state where their metabolic activities get reduced to 0.01% of normal level}.In this state, they appear to be a ball-like structure called a Tun. When these tuns are exposed to water they return to their normal life within an hour.

   

So are they really immortal?

They live for only a few months when completely active. They are said to be nearly immortal, however, according to scientists, long exposure to temperature could be a limiting factor to their tolerance. In 2016 scientists were able to revive two tardigrades who had been in a tun state for more than 30 years. The oldest tun of 120 years was revived in 1948 in Italy.

Well, this cute little animal has survived many harsh conditions and still shows no signs of giving up. we should all aim to be tardigrade tough in our lives.