45 Tardigrade Facts: Learn About This Phylum Of Micro-Animals

Tardigrades are a phylum of eight-legged divided micro-animals, sometimes known as water bears or moss piglets.

Johann August Ephraim Goeze, a German biologist, named them 'kleiner wasserbär' ('little water bear') when he first identified them in 1773. Tardigrada, which means 'slow steppers,' was given to them by the Italian naturalist, Lazzaro Spallanzani in 1777.

Life Span & Cryptobiosis State Of Tardigrade

From the top of the mountains to the mud volcanoes and deep sea, and from the Antarctic to the tropical rainforests, they've been discovered all over the planet's biosphere.

Individual species of tardigrades can survive extreme conditions that would kill most other known forms of life, such as extreme pressures (both high and low), extreme temperatures, starvation, air deprivation, dehydration, and radiation.

Tardigrades have made it to the farthest reaches of the universe.

The phylum Tardigrada, which is part of the superphylum Ecdysozoa and includes animals that grow by ecdyses like arthropods and nematodes, has approximately 1,300 species.

The oldest real members of the group are documented from Cretaceous amber (145 to 66 million years ago) discovered in North America, although they are basically contemporary forms and so presumably had a much older origin since they separated from their closest relatives around 500 million years ago.

When fully mature, adult tardigrades are around 0.02 in (0.05 cm) long.

They have four pairs of legs, each terminating in claws (typically four to eight) or suction discs, and are small and plump.

Tardigrades eat plant cells, algae, and tiny invertebrates and may be found in mosses and lichens.

They may be seen under a low-power microscope after being collected, making them available to students & independent scientists.

Tardigrades, or the moss piglet, can be found practically everywhere on the Earth, but they prefer to spend their time frolicking in damp environments like the moss that covers river stones.

According to Animal Diversity Web, a database managed by the University of Michigan, tardigrades survive their natural lives when they have adequate food and water to sustain their body processes.

Tardigrades seldom live more than two years.

Tardigrades, on the other hand, may live considerably longer if they enter a state known as cryptobiosis, which is triggered whenever environmental stress becomes intolerable.

According to the Encyclopedia Britannica, cryptobiosis causes tardigrades to enter a 'tun' condition, which slows their metabolism, reduces their requirement for oxygen, and nearly totally dehydrates their cells.

Tardigrades can live in regions with extreme conditions, where there is no water, at temperatures as low as -328 F (-200 C) and even as high as 304 F (151.1 C), in this shrunken condition.

Whenever these mummy-like tardigrades are reintroduced to water, they simply reanimate and resume their usual lives in a couple of hours.

Researchers tested Ramazzottius varieornatus, a tardigrade species in a 'tun' state, and discovered that over half of the tardigrades that were subjected to 181 F (82.7 C) for an hour died.

Active tardigrades (those not in the tun state) fared even worse.

These temperature trials reveal that most tardigrades can acclimatize to extreme temperature variations given enough time.

Tardigrades given an hour to acclimate to extreme heat died at a greater rate than those allowed a full 24 hours.

Size & Color

Tardigrades are tiny eight-legged organisms that have traveled to the furthest reaches of outer space and might even outlast the end of the world.

Tardigrades have four pairs of stubby legs and a barrel-shaped body.

The majority are between 0.012-0.02 in (0.03-0.05 cm) in length, with the biggest species reaching 0.047 in (1.11 cm).

A head, three body segments with two pairs of legs each, and a caudal segment with a fourth pair of legs make up the animals' bodies.

Tardigrade feet contain four to eight claws apiece, but the legs have no joints.

The cuticle is made up of chitin and protein and is shed regularly.

The first three pairs of legs are oriented downward along the sides and are utilized for movement, but the fourth pair is pointed backward on the final section of the trunk and is mostly used for grabbing the substrate.

Tardigrades lack multiple Hox genes as well as a big portion of the body axis in the middle. This usually refers to the whole thorax as well as the abdomen in animals.

Except for the final pair of legs, the whole body is built up of segments that are comparable to the head area in arthropods.

The number of cells in all adult tardigrades of the same species is the same.

Each adult tardigrade in some species has as many as 40,000 cells, whereas others have significantly fewer.

The bodily cavity contains a hemocoel, but the gonad is the only area where a real coelom can be discovered.

There are no respiratory organs discovered for a tardigrade; therefore, a gas interaction is possible throughout the body.

Three tubular glands are linked with the rectum in certain tardigrades; these may represent excretory structures comparable to arthropod Malpighian tubules. However, the details are unknown.

Nephridia is also not present in tardigrades.

Stylets on tardigrades' tubular mouths penetrate the plant cell, algae, or tiny invertebrates on which they eat, releasing bodily fluids or cell contents.

A triradiate, muscular, sucking pharynx emerges from the mouth of the tardigrade.

Characteristics & Features Of Tardigrades

Tardigrades are all considered aquatic since they need water surrounding their body to allow for gas exchange and to avoid desiccation. They may be found in dunes, dirt, sediments, and leaf litter, as well as in a film of water on lichens and mosses.

Tardigrades, or water bears, are generally characterized as a 'lesser-known taxonomy' of invertebrates since they are likely connected to Arthropoda (which comprises bugs, spiders, and crustaceans) as well as Onychophora (velvet worms).

Tardigrade bodies are small and plump, with four pairs of lobopodial limbs, which are weakly articulated appendages seen in soft-bodied creatures. Each limb has four to eight claws or discs at its end.

Echiniscoides wyethi is a marine tardigrade that dwells on barnacles' bodies.

In water bears, physical traits such as claws as well as the buccopharyngeal apparatus are utilized to distinguish between different species.

The tardigrade's body cavity (hemocoel) is filled with fluid that carries blood and oxygen (although the latter diffuses through the organism's integument and is stored in cells inside the hemocoel), and the animals have no known specific organs of circulation or respiration.

Their resilience is due in part to a special protein in their cells called Dsup (damage suppressor) which protects their DNA from ionizing radiation, which may be found in soil, water, and plants.

A new tardigrade species with spiky eggs has been found by scientists.

Stylets (spearlike projections near the mouth) of most plant-eating tardigrades pierce individual plant cells and then suck out the contents.

A few tardigrades are carnivorous predators.

Water bears can reproduce both sexually and asexually (using parthenogenesis or through self-fertilization.

The phylum Tardigrada has more than 1,100 species of free-living, small invertebrates.

FAQs

Are tardigrades immortal?

Although the length of their lives is unknown, tardigrades can halt their metabolism and become immortal.

What does a tardigrade eat?

The majority of tardigrades feed on algae and blooming plants, penetrating plant tissues and sucking the contents out via their tube-shaped mouths. Some tardigrades, on the other hand, are carnivorous and may consume other tardigrades.

Are tardigrades in drinking water?

Yes, tardigrades can be found in drinking water too.

Why are tardigrades so tough?

Tardigrades, also known as water bears, can be found in your garden, the deep sea, the Antarctic, and just about everywhere else. They've even made it to the vacuum of outer space. Scientists may have figured out why these tiny creatures are so tough; horizontal gene transfer (HGT). Consider HGT to be 'foreign DNA', or the exchanging of genetic material between distinct species rather than inheriting DNA only from mum and dad.

This isn't unusual, but the tardigrade genome contains more foreign DNA than any other previously sequenced genome; a staggering 17.5 %, or one-sixth of their genome, is made up of foreign DNA.

Do tardigrades have bones?

In the proceedings of the National Academy of Sciences published a study stating that there are no bones within the tardigrade's small body.