Litinsects #58: Tardigrades
Anyone recognize these weird-looking little guys? They are actually not insects, as a matter of fact they
are not even arthropods but they are cool enough to deserve a post. These are TARDIGRADES,
also known as water bears or moss piglets. They are best known for their bizarre abilities to
survive some of the most extreme conditions imaginable...
© Science Faction Images
-As always, the name’s etymology describes them a bit. It comes from the Latin “tardus” meaning “slow” and “gradior” for “step/walk”. Their common name comes from the fact that their walk looks a bit like a bear’s
-Tardigrades are a PHYLUM of
animals consisting of around 1,300 species. (Side note: the TAXONOMIC LEVEL of
a group has nothing to do with how many species it contains. For example phylum
Arthropoda, a taxonomically equivalent category consists of around 1 million
described species and possibly millions more not yet described!).
-These animals are all
microscopic, ranging in size from 0.1-1.2 mm long. They have four stubby pairs
of legs, ending in little claws. Unlike arthropods (aka “jointed-leg”)
tardigrades do not have jointed legs but they do MOLT like arthropods
Now on to the good stuff... tardigrades have been around about 500 million years, having survived all 5 major extinction events. Their ability to survive crazy extreme conditions makes them some of the most resilient animals that we know of.
They have been found: in hot springs; 6,000 meters (20,000 ft) above sea level in the Himalayas; 4,000 meters (13,000 ft) below sea level; under layers of solid ice.
They can withstand: PRESSURES many times greater than those found in the deepest oceans (that’s 1000s of times atmospheric pressure); TEMPERATURES ranging from -272°C (almost absolute zero!!!) to 150°C (that’s -458°F to 300°F) for a few minutes; RADIATION doses 100x higher than what would kill a human; and even the VACUUM OF SPACE.
Now you may be asking (and
rightly so) HOW?! Tardigrades have evolved the capability to undergo
CRYPTOBIOSIS, a state of extreme metabolic suspension, in which their
metabolism drops to 0.01% of normal in response to adverse conditions (such as too
little water, too little oxygen, extreme temps, toxins). But once environmental
conditions return to normal, they come out of their dormancy and continue right
where they left off.
Pretty fascinating little critters!
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