There’s no shortage of strange-looking and behaving creatures in the ocean, and indeed, we have yet to even scratch the surface of identifying many creatures that inhabit waters so deep, it requires months of planning and countless dollars to spend just a few hours in their realm. However, there are some pretty interesting creatures that science has been able to identify, and the strange doesn’t stop at their looks. One of these fascinating specimens is the tardigrade, more commonly known as the water bear — if you can say it is commonly known at all!
The tardigrade may enjoy a somewhat sheltered existence from the public conscious, but in fact, it is one of the most abundant creatures on the planet. It is a microscopic organism, no more than 2mm in length, that hails from the superphylum Ecdysozoa, which includes insects, crustaceans, and chelicerata (spiders, scorpions). The defining characteristic of this group is that they each shed their skin, a process called ecdysis, but the tardigrade’s similarity to other creatures ends rather abruptly there.
Our cute little “water bear” is capable of living in environments that other insects can’t, and it is found in virtually every environment on Earth: from volcanic hot springs to the poles, the top of the Himalayas to depths of more than 14,000 feet in the sea. Researchers have even launched tardigrades into orbit to see whether they could withstand the vacuum of space, not to mention the intense radiation, a journey from which they returned completely unscathed. In various tests, it has been proven that the tardigrade can withstand temperatures as low as -459F, and as high as 304F, while simultaneously taking on 1,000 times the radiation that can be withstood by other animals.
Not to be outdone by itself, the tardigrade can also go nearly a decade without water. When conditions are adverse, it goes into a dormant state, called cryptobiosis. During cryptobiosis, just enough moisture is retained to keep it alive while its exoskeleton gradually hardens to form a protective shell. Rehydration brings them back to life, a cycle which the tardigrade can repeat as often as necessary throughout its life, significantly expanding its life span. Their curious abilities have led some scientists to speculate on their true origin, especially in light of the difficulty in pinning down the evolutionary predecessors to tardigrades. If an organism can withstand conditions as severe as the tardigrade has been exposed to, there is a possibility that perhaps they were migrants from another planet.
Tardigrades are so abundant in the world’s ecosystems that a bit of foraged dry moss, beach sand, seawater, soil, or freshwater sediment likely holds at least one, whether active or in cryptobiosis. So grab yourself a microscope, a petri dish, and some natural debris and try your luck at hunting the world’s most common “bear”!
Images via Wikimedia Commons