Though humans have accomplished so much since we first evolved, the time we have spent on Earth is only a mere blip compared to some of Earth’s most durable and extraordinary creatures. These animals have needed to survive in situations much harsher than those humans have experienced. Perhaps studying these creatures may help us face some of the diseases and illnesses that continue to challenge us.
Naked Mole Rat
Besides their fashionable appearance, naked mole rats are significant to scientists for one key reason: they do not get cancer (at least, as far was we can tell) (1). To humans, this quality seem nothing short of a superpower. Scientists are now sequencing the mammal’s genome in order to gain insight on how it resists cancer. Some theorize that its cells are extra sensitive to contact inhibition — the signal preventing cells from growing once they come into contact with other cells in the body. Cancer cells can bypass this contact inhibition and convince neighboring cells to continue to proliferate. Since naked mole rats spend their lives underground, perhaps this extra sensitivity was originally an adaptation that evolved to make the animal more sensitive to vibrations in it home for proper danger perception and navigation.
But of course, nature can kill us in many other ways than cancer. No oxygen? No problem. Naked mole rats can go about 18 minutes without any oxygen. Predator sneaking up on you? Naked mole rats can run forward just as fast as they can run backwards. Bad living conditions? Well, the naked mole rat wouldn’t know; it is immune to pain.
Planaria just so happen to be my favorite organism. Their eyes appeared to be crossed, but in most science classrooms planarian don’t get to use their eyes for very long. Why? Well, because we decapitate them (2).
What happens to planaria when we decapitate them is extraordinary. Both pieces of the planarian will continue to live. The piece of the planarian with its head will regenerate a tail while the headless piece will regenerate a head (with a fully functional brain!) And now you have two planaria! Some studies show that the two new planaria, even the one that has an entirely new head, will have retained the memories they acquired from their original body (3)!
Better yet, planaria can regenerate themselves from nearly any cut. Harriet Randolph devoted his life to studying planaria and found out that a single planarian can be cut up into 279 pieces just the right way for each piece will regenerate the rest of its body and fully recover into a planaria (4). Planarian can achieve this due to their abundance of stem cells.
At the moment, horseshoe crabs have the most significant role in our lives than all the other organisms in this list. This species has been around over 445 million years; that’s before the dinosaurs! Their importance to us, though, comes from their baby blue colored blood.
A horseshoe crab’s blood is blue because it carries oxygen using hemocyanin while our blood uses hemoglobin. The main difference between these cells is that hemocyanins are copper based while hemoglobins are iron based (5). Horseshoe crab’s don’t have an immune system like ours featuring white blood cells that hunt down and attack invaders. Instead their amebocyte cells find the invader and seal it inside a gooey cage so it cannot spread. Scientists harvest this blood and use the amebocyte cells to test the safety of needle injections for humans required for delivering vaccines and drugs. In the past, scientists used animal models to test the safety of injections — a process that was tedious, often inaccurate (anyone’s heart might start racing at the sight of needle), and led to many animal deaths. Now scientists can simply monitor the amebocyte cells that come into contact with the injection; if the amebocyte cells start to surround the sample with goo, the product is not yet safe for humans.
Most biologists agree that this organism is the most resilient creature known to man. The more we learn about them, the more impressive they seem. Don’t be fooled by their gummy-bear-like appearance; tardigrades can survive such extreme heat and cold that they can be found nearly anywhere on earth! This includes Antarctica, the desert, and the highest mountaintops. They have also been shown to withstand high levels of radiation and even the vacuum of space!
One key feature that allows them to survive in space is that they are anhydrobiosis. This means that in period of limited access to water, tardigrades can curl up and continue to survive in a cyst-like state. In this dried up state, its body produces a matrix like jelly in its cells to take the place of water to paralyze the organelles and halt metabolism (6). Incredibly, tardigrades can live without water for up to 10 years! Humans, on the other hand, may last only about 100 hours without water. Scientists are now trying to figure out what other molecules and processes make these organisms virtually indestructible. One study found that protein in the tardigrade called Dsup is capable of acting as a DNA shield during high levels of radiation, preventing the important molecule from breaking apart (6).