Tardigrades:
Tardigrades belong to the phylum Tardigrada of kingdom Animalia.
Lazzaro Spallanzani in 1777 named them Tardigradum which means "slow walker". Tardigrades are eight legged microscopic animals. They’re commonly known as water bears or moss piglets.
We have discovered 1000+ species of tardigrades till now. The name "water-bear" comes from the
way of their gait, as they look like a bear walking; Mosses and lichens are
their preferred habitat hence their nickname, moss piglet.
Most species are found to be living in freshwater or
semiaquatic terrestrial environments. They’re considered aquatic because they
need water around their bodies for gaseous exchanges as well as to prevent
themselves from drying out (desiccation).
Tardigrades are covered in a tough cuticle, similar to the exoskeletons of grasshoppers, praying mantises, and other insects to which they are related. They have four to six claws on each foot, which helps them cling to plant matter, and a mouthpart known as bucco-pharyngeal apparatus, which helps to suck nutrients from plants and microorganisms.
Tiny,
tough and resilient:
Tardigrades belong to an elite category of animals known as
extremophiles (or critters). They can live at temperatures as cold as absolute
zero or above boiling, at pressures six times that of the ocean’s deepest
trenches, and even in the vacuum of space. They can even survive up to 30 years
without food or water.
In 2007, scientists discovered the water bears can survive
an extended stay in the highly radioactive vacuum of outer space.
A European team of researchers sent a group of living
tardigrades to orbit the earth on the outside of a FOTON-M3 rocket for 10 days.
When the water bears returned to Earth, the scientists
discovered that 68% lived through the ordeal. Their resiliency is in part due
to a unique protein in their bodies called D-sup (Damage - suppresor protein) which
protects their DNA from being harmed by ionizing radiation present in soil,
water, and vegetation.
Cryptobiosis in tardigrades:
Another amazing survival trick that water bears have down
their sleeves is cryptobiosis, a state of inactivity which is triggered in a
dry environment. They shrivel up, losing all but around 3% of their
body's water and slow down their metabolism down to just 0.01 % of its normal
rate.
In this state, the tardigrade just persists against the
conditions, doing nothing, until it's exposed to water again. When that
happens, the creature pops back to life like a re-wetted sponge and continues
onward as if nothing had happened.
How are tardigrades useful to us?
Tardigrades can survive being in cryptobiosis for more a decade. According to some researchers some species of tardigrades might even be able to survive desiccation for up to a century.
Yet the average lifespan of a (continuously hydrated) tardigrade is rarely longer than a few months.
If we humans can replicate cryptobiosis in the way tardigrades do, we'd live far longer than the average life expectancy which might prove helpful in future interstellar travels.
Informative!
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