Global warming are very dramatic even for tardigrades, Global warming, a key aspect of climate change, already has many negative impacts on many of our planet’s habitats.Therefore it is important to understand how rising temperatures can affect animal health and well-being.
A research team has just shown that tardigrade is very vulnerable to long-term exposure to high temperatures. Small, dry animals are known for their extreme tolerance for extreme environments. Tardigrades, commonly known as water bears or mossy pigs, are microscopic invertebrates that are common throughout the world in marine, freshwater and terrestrial microhabitats.
Surprisingly, the researchers estimated that the average lethal temperature for unconditioned active tardigrades was 37.1 ° C, although the short acclimatization period resulted in a small but significant increase in average lethal temperature to 37.6 ° C. not far from the maximum temperature measured today in Denmark, i.e. h. Regarding dry samples, the authors found that a mortality rate of around 50% after one hour of exposure was 82.7 ° C, although a significant reduction to 63.1 ° C was reported after 24 hours.
The research team used a logistical model to estimate the average lethal temperature (where 50% of deaths were achieved) for active and dry tardigrades. So far, about 1,300 Tardigrad species have been described. The bodies of these small animals are vat shaped (or dorsoventral compressed) and divided into heads and frames with four pairs of legs.
Their body length varies between 50 microns and 1.2 millimeters. In addition to their impressive ability to survive in extreme environments, tardigrade is also very interesting because of their close evolutionary relationship with arthropods (eg insects, crustaceans, spiders).
Like aquatic animals, tardigrades must be surrounded by a layer of water so they are active (ie feed and reproduce). However, this creature is able to survive in the dry period (anhydrobiosis) by entering cryptobiose, e.g. ametabolic state is reversible, often in limestone species. In short, the Tardigrades entered the so-called “do” state by contracting their front and rear body axes, harvesting their legs and rearranging internal organs.
This gives them the ability to survive in harsh environmental conditions such as lack of oxygen (anoxibiosis), high concentrations of toxic substances (hemobioses), high concentrations of solutes (osmobioses) and very low temperatures (cryobiose).
Tardigrades extreme tolerance to extreme environments also includes high temperature resistance. However, some types of Tardigrade have been reported to withstand temperatures up to 151 ° C. However, the exposure time is only 30 minutes. Other studies on the thermal tolerance of dry (anhydrobiotic) tardigrades have shown that exposure above 80 ° C for 1 hour causes high mortality, with almost all specimens dying at temperatures above 103 ° C exposed to high temperatures for long periods, ie. more than 1 hour.
Tardigrades are able to withstand harsh environmental conditions, but their resistance to high temperatures is very limited, and this could actually be the Achilles’ weakness of these otherwise super-resistant animals.