Toughest micro-animals might not survive climate change
Tardigrades that can remain alive for 30 years without food and water might not sustain an increase in temperature caused by climate change.
A new study published in “Scientific Reports” journal suggests that tardigrades -- one of the toughest animals found on the earth -- might not sustain the heat caused by climate change.
These mini-animals came into light recently when the world’s first private spacecraft supposed to land on the Moon (sent by Israel) crashed a few hours before landing.
The spacecraft contained tokens, including thousands of tardigrades. Scientists had sent them on the Moon to see where all they can sustain.
What are Tardigrades?
Tardigrades are microscopic organisms with a barrel-shaped body. They are found in marine, freshwater and other wet places. They are also known as water bears or moss piglets. Their body is divided into a head and a trunk with four pairs of legs. They measure up to 50 micrometre and 1.2 millimetres.
How are they different?
They can switch-off their body and survive without food and water for up to 30 years. The inactive state known as cryptobiosis reduces the amount of energy consumption to an undetected level.
In the inactive state, tardigrades retract their legs and rearrange their internal organs. It can allow them to sustain in environments with lack of oxygen, high toxicant concentration, high solute concentration and extremely low temperatures. They are also resistant to radiation in space.
The new study on their tolerance:
A research conducted by the University of Copenhagen said that tardigrades couldn't withstand long-term high-temperature exposures.
Scientists studied one of the species of tardigrades -- Ramazzottius varieornatus. The latter are found in freshwater habitats. The samples were obtained from a gutter of a house in Denmark. The researchers evaluated the effect of exposure to high temperature in active and desiccated tardigrades.
While experimenting, researchers estimated the lethal temperature for the non-acclimated (those who are not accustomed to a new climate or condition) tardigrades to be 37.1°C. A short acclimation period leads to an increase in the lethal temperature to 37.6°C.
The temperature in Denmark is close to a lethal temperature i.e. 36.4°C. It suggests that climate change can be really bad for these organisms.
While comparing desiccated specimens, authors observed 50 per cent mortality temperature at 82.7°C if the organism got an exposure of an hour. If they were exposed for 24 hours, the lethal temperature decreased to 63.1°C. An increase in temperature can lead to constant exposure to high temperature while it can increase the mortality rate to 50 per cent, as observed.