Global Warming Would Be Dramatic for Tardigrades, Too

Global warming, a significant part of climate change, is already inflicting a wide range of adverse effects on many habitats of our planet. It is for that reason of the utmost significance to understand how rising temperatures may affect animal health and welfare.

A research group from the University of Copenhagen's Department of Biology has just shown that tardigrades are very liable to long-term high-temperature exposures. Animals, which in their desiccated country, are pleasantly recognized for their high tolerance to severe environments.

Ricardo Neves, Nadja Møbjerg and associates at the Department of Biology, University of Copenhagen presented the effects of the tolerance to high temperatures of tardigrade species in a study published in Scientific Reports.

ALSO READ: How Do Water Bears Survive Extreme Heat and Deadly Environments? Answers Unveiled By Researchers

Tardigrades, commonly known as water bears or moss piglets, are microscopic invertebrates found worldwide in marine, freshwater, and terrestrial microhabitats.

The team investigated the tolerance to excessive temperatures of tardigrades obtained from roof gutters of a house located in Nivå, Denmark. 

Neves and his team evaluated the impact of tardigrades when exposed to hot temperatures and dry conditions. The group additionally investigated the influence of a brief acclimation length on lively animals.

The researchers found that the median lethal temperature is 37.1°C for non-acclimated active tardigrades. However, a quick acclimation period ends in a small but considerable increase of the median at a deadly temperature of 37.6°C. 

Interestingly, this temperature isn't a long way from the presently measured maximum temperature in Denmark. As for the desiccated specimens, the authors placed that the expected 50 percent mortality temperature is 82.7°C after 1-hour exposures, but decreases to 63.1°C following 24-hour exposures.

The research used logistic models to estimate the median lethal temperature (at which 50% mortality is achieved) both for lively and desiccated tardigrades.

Approximately 1300 tardigrade species have been defined so far. The body of those minute animals is barrel-shaped and divided into a head and a trunk with four pairs of legs. Their frame duration varies between 50 micrometers and 1.2 millimeters. Apart from their impressive capacity to tolerate extreme environments, tardigrades are also very interesting due to their near evolutionary relationship with insects, crustaceans, and spiders.

Tardigrades, as aquatic animals, need to be surrounded in a film of water to be in their active state. However, these critters can bear dry conditions by way of entering a reversible ametabolic state. Succinctly, tardigrades enter the so-called "tun" country through contracting their anterior-posterior frame axis, retracting their legs, and rearranging the internal organs. 

The environment gives the tardigrades the potential to tolerate extreme environmental situations consisting of oxygen depletion, high toxicant concentrations, excessive solute concentration, and extremely low temperatures.

The top-notch tolerance of tardigrades to severe environments includes additionally excessive temperature endurance. Some tardigrade species had been said to tolerate temperatures as high as 151°C. However, the exposure time was the simplest of 30 minutes. 

Indeed, even though tardigrades are capable of tolerating a diverse set of severe environmental conditions, their persistence to excessive temperatures is rather restrained, and this might surely be the Achilles heel of those otherwise super-resistant animals.