Tardigrades-Extremophiles who have survived all the mass extinctions!!

These little organisms called, Tardigrades were first found in 1773 by Johann August Ephraim Goeze, a German biologist who named them "little water bears." Italian researcher Lazzaro Spallanzani named the group "Tardigrada," or "slow stepper," For its toddling walk, three years later.


Morphology of tardigrades-

Tardigrades, sometimes known as water bears or moss piglets, are aquatic animals with fat, segmented bodies, and flattened nearly tiny skulls. They have eight legs with four to eight claws or digits on each. Water bears can grow to be 0.002 to 0.05 inches (0.05 to 1.2 millimeters) long, but they seldom exceed 0.04 inches (1 millimeter).

Photo credit-www.theguardian.com


Tardigrades as extremophiles-

Extremophiles are organisms that can survive a wide range of environmental conditions such as cold, heat, and high salinity. Water bears can be found almost anywhere there is liquid water, including the ocean, freshwater lakes and rivers, and the water film that covers terrestrial mosses and lichens. They can thrive in a broad range of environments, from the Himalayan mountain range's elevations of over 19,600 feet (6,000 meters) to ocean depths of more than 15,000 feet (4,700 meters). They are also one of the few organisms which have survived all the five mass extinctions.


Water bears have an odd approach for surviving extreme conditions: they enter a near-death state known as cryptobiosis, in which they expel more than 95 percent of their body's water, retract their heads and legs, and curl into a parched ball. Tardigrades can withstand extreme pressures, up to six times those found on the ocean floor, as well as being boiled in alcohol.

Photo credit-researchgate.net


What do they eat and their mode of reproduction-

The majority of tardigrades drink fluids from the plant, algae, and fungus cells, puncturing cell walls with needlelike stylets in their mouths and sucking up the liquid inside. Some species, such as rotifers, nematodes, and even other tardigrades, can swallow entire living things. Depending on the species, tardigrade reproduction can be sexual or asexual. Some reproduce by parthenogenesis, which is the development of an embryo without the use of external fertilization.


Tardigrades in space-

The tardigrades arrived at the ISS on the SpaceX Dragon cargo spaceship on June 5, 2021. The Cell Science-04 water bears, on the other hand, aren't the first tardigrades to travel to space. In 2007, a European research team sent 3,000 living tardigrades into Earth orbit on the exterior of a FOTON-M3 rocket for 12 days and exposed them to the vacuum and radiation of space. Over two-thirds of them were successfully resurrected upon their return to Earth. Many died soon after, yet they were still able to reproduce before they died. The objective of sending them to the space is to learn about their survival strategies and study their genes.

Photo credit-askabiologist.asu.edu

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