Water bear! What do you picture? A swimming bear?… Well, we know that the skillful swimming bear is polar bear, but what exactly is water bear? Water bear, or also known as Tardigrade, or moss piglet, is actually a near-microscopic animal. They have related to Arthropoda and Onychophora or velvet worm. Tardigrade is called water bear because of their claws, bulky body, and snout-like mouth, just like bear.
Yes, water bear is not the same polar bear. It’s not even a bear!
Water bear vs polar bear; do they have the same habit?
So what is that?
Tardigrades have a long plump body, bilaterally symmetrical, segmented organisms, with eight legs, and claws on each hand. Their bodies are short, only up to 1.2 mm in length.
Water bear eat, fluids of plant cells, animal cells, bacteria, amoebas, nematodes, or even other tardigrades! Some also found to be entirely carnivorous. They reproduced by sexual and asexual. reproduction.
Tardigrades are insanely indestructible!
They may look odd, but insanely strong. First of all, you can find them everywhere! They can live in almost every habitat on earth, from on the top of mountain, in the wild of tropical rain forest, until the coldest place like Antarctic. But most of them live freshwater and semiaquatic environments, like linches, mosses, leaf litter, or sediments, since water is one of substantial matter to them. They need water to permit gas exchange and to prevent uncontrolled desiccation.
They can survive in the condition with minus 200-degree Celcius to the boiling liquids like alcohols, able to survive from radiation like lethal amount of X-ray, six times of high pressure of the deep ocean, from lack of oxygen and the lack of water, and also survive from some chemicals.
When you think it can get any ridiculous, studies found that Tardigrades can probably survive for ten days while being exposed to the vacuum of space! Other researchers said tardigrades could be unaffected by space catastrophic such as a large asteroid or nearby supernova impacts. This also means that they are even able to survive after humanity is long gone!
How do they do that?
So, tardigrades, or water bears, have adapted to these environmental stress by a process called cryptobiosis. This process allows water bear’s metabolism activity become reversible standstill, or like in a ‘death’ situation, by curl themselves into a dehydrated ball or also known as a tun. This form also prevents ice crystal to grow on them when they have to survive from extremely cold temperatures. They can come back to life if reintroduced to the water. In the cryptobiosis state, their metabolic activity gets low to 0,01 percent of the normal state, and their organs are protected by surgary gel and antioxidants. Yes, they can produce a large amount of antioxidant and protein to protect their vital organs and DNA.
How about polar bear?
Now let’s compare water bear to the polar bear. Well, polar bear is not strong enough to survive from space catastrophe, but they do have a strong adaptation to the extreme weather in Arctic!
We know that during the cold months, Arctic region daily temperature may reach down around minus 20 degrees of Celcius. To be able to live in this such condition, arctic animals have developed interesting ways to deal with the cold, including polar bear.
Polar bear’s skill
Polar bear has a big body. They can weigh between 150 to 700 kilos and 1.20 to 1.60 meters tall at shoulders. They are also skillful swimmers and spend most of their times underwater to hunt for food, which makes them also called as marine mammal. They adapt their nostrils to close when they dive to hold their breath until up to two minutes underwater.
They don’t need to hibernate!
Unlike the others mammal who hibernate during winter to stay alive, polar bears don’t have to put themselves to sleep because even in the coldest month, there is still plenty of food source for them to eat. They also have double fur coat to keep them warm and metabolic in the stable rate. The fur is divided into inner coat and outer coat. The outer one is thicker and has function to protect the softer and denser inner layer. Some studies also suggest that polar bear’s coat traps the air bubbles in the environment or even the said that the skin able to emits electromagnetic wave to keep their bodies warm. Other factors that help them to reduce their heat loss is their body structure: the compact ears and small tail also have role to keep their body temperatures.
But polar bear still has to lay low during bad weather by digging themselves into the snow or moss to stay away from strong winds during winter or heat during summer.
On the other hand, pregnant females can stay fasting in their dens for about three months before giving birth to the cubs. They survive from the fat reserves when they don’t eat at all during this period. This also the longest fast period compares to other mother mammals.
It is hard to compare these two animals who shared the same ‘bear’ name, because even from their morphological structure, they are completely different from each other. One is near microscopic animal who got the bear’s name because the claws, body, and snout mouth, one is a … snowy giant bear, live in polar region.
But we must agree that both of them have developed amazing adaptation to the extreme condition. Water bear can survive for like most of the disastrous event by a process of cryptobiosis or putting themselves into the death-like situation. Polar bear, in the other hand, is strong enough to not to hibernate during the cold months since there is enough food source for them eat and the complexion design of the body to prevent them from getting cold in the coldest temperature like in Arctic.