Bear worm

Water bear, also known as water bear, is the common name of the creatures in the slow-moving animal kingdom. There are about 900 recorded species, many of which are distributed all over the world. Water bears are so small that they can only be seen clearly with a microscope. The surface of the water bear is covered with a water film to prevent the body from drying, and at the same time it can breathe oxygen in the water film. They mainly live in the sediments of fresh water, moist soil and the water film of bryophytes, and a few species live in the intertidal zone of seawater and make a living by sucking the juice of animal and plant cells with sharp needles. The biggest feature is that you are an adult when you are born from an egg. Without childhood, the number of cells in the body remains unchanged for life.

Water bears are the most vital creatures on earth, and can survive in unprotected outer space, in the Himalayas (above 6000m) and deep sea (below 4000m).

Tardigrada has all four kinds of cryptobiotics (namely, low humidity cryptobiotics, low temperature cryptobiotics, osmotic cryptobiotics and anoxic cryptobiotics), which can stop all metabolism in harsh environment. Therefore, slow-moving animals are considered to be the most vital animals. In the case of cryptobiotics, they can generally survive for several minutes to several days at high temperature (15 1℃), near absolute zero (-273. 15℃), high radiation, vacuum or high pressure. It has been recorded that slow-moving animals have been dormant 120 years.

Low temperature cryptogenesis

Low temperature will cause low temperature cryptogenesis. Slow-moving animals can be frozen first and then thawed to recover without causing harm to their bodies. 1975 Crowe put the active Dactylogyrus into 2ml-20℃ water. All experimental animals enter the keg state immediately. It takes only one minute to thaw in water at 4℃, and 80% of the animals successfully wake up.

Low humidity cryptogenesis

This is the most common form of cryptogenesis, which will happen when the living environment of slow-moving land animals begins to be short of water. But when they touch water again, they can move again in a short time. Including slow-moving animals on land, only they can survive in water. If the surrounding liquid is diluted or even lower than the concentration of body fluids, slow-moving animals will curl up into a ball. The nail plates on the back will be stacked together, and the elastic cuticle between the nail plates will shrink. Enter the so-called "barrel stage".

The main reason for entering the "keg state" is lack of oxygen. When the ventilation is stopped in the experiment, the slow-moving animals will contract. But muscle contraction in water can't last long. Therefore, the "small bucket" will stretch again when it meets water, but the individual will immediately enter a state of suffocation.

The premise that slow-moving animals can survive the water shortage period is that the process is slow and the air humidity cannot be too low. The drying process is too fast for slow-moving animals to shrink. In the experiment aimed at this premise, it can be observed that slow-moving animals are tightly pressed on the surface and it is difficult to recover.

Hypoxia cryptogenesis

Hypoxia occurs when the oxygen content in the liquid around a slow-moving animal is below the threshold. At first, slow-moving animals contract first, but then they will stretch to the maximum, and they are also in a state of suffocation, unable to excrete water from their bodies. Some species can live for five days without oxygen. The metabolic state of slow-moving animals when they are dormant under hypoxia is unknown.

Variable permeability cryptogenesis

Osmotic cryptogenesis has not been well observed. Infiltration is caused by the increase of osmotic pressure in the environment. Bufo gargarizans can still move in 0.4% salt solution. In 15% salt solution, it will enter the keg state within 9 seconds. Echinococcus can suffocate in fresh water, but if it is put back into seawater, it will wake up within three days.

Cystic form

Going through a difficult period in a cyst is not a cryptogenic disease.

Species living between moss and hay, especially freshwater species, can survive through this cyst. In this state, slow-moving animals will shrink to only 20% to 50% of their original volume, reduce metabolism and even decompose some organs. This process is accompanied by three consecutive molts, and finally, the animal will be surrounded by a multi-layer cuticle shell. In this state, slow-moving animals can live for a year. When the environment changes back, the individual can shell in 6 to 48 hours.

The formation of cysts only occurs in water. It is not as good as the temperature resistance of small barrel, and its water content also determines that it does not have high temperature resistance.