Tardigrados: What are they, where they live and size

Tardigrades are animals microscopic invertebratespopularly known as Water bears or water bears Because of its appearance, with robust but rounded shape, and its quiet displacement. The size of a lategrade is on average 17 tenths of a millimeterso they are not visible to the naked eye.

Water bears are the most resistant world in world because they can survive extreme conditions. To be able to overcome them, they go through a peculiar state known as cryptobiosisin which his metabolism stops. When conditions are good again, metabolism is reactivated. This allows them to protect against desiccation, because they lose 80% of their weight that is water. This state is also called anabiotic, and catalogs within the Extremophile organisms. In addition to tolerating desiccation, they can support -273 ºC up to 151 ° C, also in cryptobiosis.

Tardigrados or water bears belong to Tarded edgeand are identified by certain physical characteristics that we present below.

In this other article you can learn more about extremophiles: what are, characteristics and examples.

• The size of the tarded is very small, measuring the smaller five hundredths of a millimeter and seventeen tenths of millimeter on average. This means that it is only possible to see the tarded in samples for the microscope.
• The question arises where the tardigrades live. The main thing is that they are always associated with water, so they are known as water bears. It might think that they are animals that live in the sea or in lakes floating in the large amount of water. However, although there are some marine and other sweet species, most late are not in aquatic ecosystems, but are in terrestrial media. Mainly, they live in the thin water film that extends On top of mosses, lichens and litter of humid forests. Some can also be found in great sea ​​depths, on algae, in hot springs or in rivers.
• There are in different colorslike red, blue, purple, coffee, yellow, green or even transparent.
• The feeding of water bears is based on the content of plant cellsand from there comes the color of his skin. For example, oranges get the carotenoid pigment that is of this color. Sometimes they can consume small protozoa or nematodes. To suck the cell content, they have stiletto in the mouth that inject to absorb cell juices.
• They have a body Short and segmented cylindricalin parts called metamers. They have four pairs of legs, that is, they have Eight legswhich are short and provided with large nails. These legs are peculiar because they are not articulated, as they are in all other arthropods.
• It seems that they have no head because it is not differentiated from the body, but it is distinguished by being extremely anterior and by the opening of the mouth.
• How many years can a lategrade live? In conditions without cryptobiosis, that is, without extreme conditions, they live an average of three years. But if they are In a state of latency, they can live up to 100 years.

Tardigrades can be divided into three taxonomic classes. They are identified by the number of nails and by the type of reproductive system:

• Mesotardigrada class: Each leg has six nails, of the same length as the leg. It only has the species Thermozodium Esakii. The only record that was lost in an earthquake, so your reproductive system is not known.
• Heterotardigrada class: The legs have four nails. Their gon pipelines open abroad.
• Eutadigrada class: It is the group that has the most species, with 700 of them. The legs have two nails. His gon pipelines open towards the rectum.

• Have separate sexesthat is, there are males and females.
• Exist Two ways to fertilize To the female: it may be that the male releases sperm into the female sewer or that they injected with the external tissue.
• The result of said fertilization are eggswhich are equally resistant to the adverse conditions that adults.

• It is incorrect to say that late are dangerous. They have no poison or transmit diseases. In fact, they are studying for Use your radiation resistance to apply to the field of medicine.
• The importance of tardigrades lies first in their place in the trophic chain. On the other hand, they have been very investigated for their capabilities of Cryptobiosis survival.
• It is said that there is Tardigrades on the moonbecause they came in a spacecraft that had to land on the moon. However, most likely They have not survived Due to the lack of water in this satellite, because as we know, water bears depend on vital fluid.
• The late name means “Slowly”, Which refers to the slow movements with which these animals move.
• Exist 750 species of tardigrados.
• They have a certain number of cells by species.
• They can’t see. They have pigmented cells that make a similar function, with which they only detect shadows and changes in light.
• They have no complex respiratory system. They only do the gaseous exchange by diffusion through the cuticle.
• Some of the extreme conditions that tolerate are High salinities, alcohol, ether and radiation.

Now that you know what the tarded are, you can discover more microscopic fauna, such as these curious water bears, in this other article about microfauna: what is and examples.

If you want to read more articles similar to Tardigrados: What are they, where they live and sizewe recommend that you enter our biology category.