The fascinating world of tardigrade by AimanHakim

aimanhakim183189 — 2025-05-25 22:50:53 UTC

Tardigrade are a unique animal known for their hardiness even with their small size of 0.5mm. They are usually found in Mosses or lichens. So they can be easily viewed by standard microscope.

Their are first found in 1773 by German zoologist Johann August Ephraim Goeze and them named them “Kleiner Wasserbär,” or “little water bear” after their resoundingly cute and unmistakably bear-like appearance. Five years later, Italian scientist Lazzaro Spallanzani would name them “tardigrada” or “slow steppers” in recognition of their strangely sluggish gait.

So far 1,300 species has been identified in Tardigrade though it’s difficult to put a true number on it because of difficulties differentiating species). The truth is this may only represent a small portion of their diversity. The earliest fossil of Tardigrade indicated that they have existed about 500 million years.

aimanhakim183189 — 2025-05-25 23:04:26 UTC

Tardigrades are short, plump, and covered in a tough cuticle (similar to that of grasshoppers and other insects) that they must shed to grow. They have four pairs of legs, with 4-6 claws on each foot. Their specialised mouthparts – called a bucco pharyngeal apparatus – allows them to suck the nutrients out of plants and other microorganisms. They have no bone but instead hydrostatic skeleton- a fluid-filled compartment known as a hemolymph. They have no spinal cord but do have a similar system in place – a ventral nervous system that sends signals between the brain and body. Their movement is similar to that of an insect. The special thing about Tardigrade is their ability to survive in extremely harsh conditions. Their live span is between 3 months to 2.5 years.

aimanhakim183189 — 2025-05-25 23:21:22 UTC

They have shown to be able to survive :

Low temperatures of 0.05 kelvins (-272.95 degrees Celsius or functional absolute zero)

High temperatures of 150 degrees Celsius

Pressures of 40,000 kilopascals

The burning ultraviolet radiation of space

Being shot from a high-speed gun (traveling at nearly 3,000 feet per second and the impact of 1.14 gigapascals of pressure) Being stored in a freezer for 30 years

Even surviving an impact of an asteroid

The most amazing part is that they survive all five major mass extinction event!

Tardigrade are able to survive all of these by making of a state called tun.

aimanhakim183189 — 2025-05-25 23:23:42 UTC

How does it work?

aimanhakim183189 — 2025-05-25 23:25:39 UTC

Though tardigrades can be found in moss and lichens, they are still – as per their evolutionary history – truly an aquatic animal. They require a film of water to surround their bodies to allow them to take in oxygen and expel carbon dioxide. Without this, they start to dry out, stop metabolising, and curl up into a desiccated form known as a “tun.” The incredible thing is that at the faintest whiff of water, they immediately bounce back into their original metabolising state.

aimanhakim183189 — 2025-05-25 23:40:22 UTC

Anoxybiosis and encystment, described in the upper part of this figure, are responses one might see in a variety of organisms. The bottom half of the chart shows three states of cryptobiosis, in which metabolism is suspended—an act usually diagnostic of death. Cryobiosis occurs in response to freezing, and anhydrobiosis in response to drying. During the latter, an organism surrenders its internal water to become a desiccated pellet. Both result in the formation of a durable shrunken state called a tun. More rarely, a tun is created to resist osmotic assault, which requires water. In the tun state, tardigrades can survive for many years, impervious to extremes far beyond those encountered in their natural environments.

aimanhakim183189 — 2025-05-25 23:43:23 UTC

tardigrades are not technically classed as “extremophiles” because they do not thrive in harsh conditions – they simply survive. There is also some confusion between the tardigrade’s sheer hardiness and its ability to live forever. In reality, tardigrades only have a lifespan of a few months – in the active state. This can (and is) interrupted by long periods where they are (to all intents and purposes) “dead.”

aimanhakim183189 — 2025-05-25 23:58:26 UTC

We call the tun stage, a "half dead" stage. Well, according to all traditional definitions of life, there must be some form or reproduction and metabolism involved. In their tun state, tardigrades are doing nothing that we would associate with being alive – they are not making or consuming ATP at all. They are indistinguishable from dead or inorganic matter. So, are they really alive? This is yet another debate we will have to leave to the experts.

aimanhakim183189 — 2025-05-26 00:10:37 UTC

Tardigrade are truly a fascinating creature. The fact that these little creature is so durable make it stand out among their relative species. It is amazing that the only thing that can stop these creature is old age, it show how resilient these creature.

It amazing how they can adapt to any condition. This challenge the way we think about animal.

aimanhakim183189 — 2025-05-26 00:11:17 UTC