 Have you ever noticed how we react differently to different circumstances? We sweat profusely when it's too hot and then again we shiver non-stop when it's too cold. But why is that? Well, your body needs to maintain your optimal internal environment or it needs to maintain homeostasis. Homeo means constant and stasis means stable. So homeostasis is the tendency to maintain a stable, constant stable internal environment, kind of like a constant state of balance. That means when you're sweating or when you're shivering, your body is trying to maintain the internal temperature within a certain range, which is around 37 degrees Celsius. This thing, the way you react to your surrounding temperature by maintaining your own, is a response to a non-living or abiotic factor and it isn't just about temperature. Homeostasis is also about maintaining other factors too, like the pH levels of your blood and even your blood glucose. Now different organisms react to their surroundings differently. Some behave just like us. Too stubborn to change their internal environment, they're called regulators and then there are these other organisms that don't mind changing their inner selves according to their surroundings. They're called conformers. Let's break down each of these responses and find out how exactly do they work. Let's start with us regulators. All mammals and birds are exclusive regulators. That means all of them can maintain a constant internal environment, like a constant body temperature, constant pH, constant osmotic concentration, which by the way is the concentration of water and salts inside the body and all of this is maintained at the expense of energy. For example, if your body wants to generate heat, it will do so by releasing energy from the breakdown or metabolism of food. This thing where we are maintaining our own body heat or body temperature is called thermoregulation and when we are maintaining our osmotic concentration, then that is called osmoregulation and only us warm-blooded animals or in a fancier way endotherms can do this. We are the only ones who can thermoregulate and osmoregulate and because of this property, us endotherms can survive pretty much anywhere on this planet. Be it the Sahara Desert or the Arctic regions, all endotherms including us will be doing just fine. But not all organisms can maintain this constant internal environment. They can't generate enough internal heat like we do or they cannot regulate their osmotic concentrations like a pro. That means their body temperature or osmotic concentration fluctuates with their surroundings. These organisms are called conformers. When their body temperature fluctuates, they're called thermoconformers or heat conformers and this is mainly seen in most reptiles, amphibians, fishes and even some insects. These animals are also called cold-blooded animals or in a fancier way you can call them ectotherms. When their osmotic concentration fluctuates, they're called osmoconformers. Most marine invertebrates are both thermo as well as osmoconformers like the octopus, the starfish and lobsters. That means that these animals, they can match their internal body temperature as well as their osmotic concentration to their surroundings which is the sea which is present outside. However, some thermoconformers can osmoregulate. That means they can regulate their osmotic concentrations just like we do. These mainly include most fish. Fishes are ectothermic osmoregulators, which means that they are ectotherms that can regulate their inner osmotic concentrations. Now, if we place our regulators and conformers on the two ends of our biology response spectrum, then some organisms will appear right in the middle. They're called, these organisms, they're called partial regulators. These fellows, they cannot deal with the huge energy requirement of a complete regulator. So they end up doing a half-and-half thing. They maintain their internal environment, for example, their temperature, up to a certain range that they can afford and then they can match it up to match it to their surroundings beyond that point. An animal that does this is the silkworm moth. Now, let's try something. Here I have this graph where I have internal temperature and external temperature on the two axis over here. What we're gonna do is that we're gonna try and plot the responses that we just talked about on this graph. So how do you think a regulator will respond with respect to this graph? So we know that regulators don't change their internal temperature is irrespective of their external temperature. So they're gonna be just this one very long straight line where they're maintaining their internal temperature no matter how much the external temperature is becoming. How about the conformer then? Where, how do you think that's gonna look like? Well, the conformer is is going to change its temperature with the with the external temperature, right? Their internal temperature will rise if the external temperature also rises. So based on that, we are going to have something like this where the internal temperature rises along with the external temperature. Then finally, we have our middleman, which is the partial regulators. Now they're gonna do the half-half thing, right? They're gonna have the best of both worlds. So they're gonna look something, a half of it will look like the conformer. So we're gonna have a line looking like the conformer and then the remaining half will look just like the regulator because they'll start maintaining their internal temperature. So this is how it will look. Now in the end, to sum it all up, then we're gonna have our regulators maintaining their temperature just fine. Then we have the conformers where they're gonna change it constantly. And then we finally have the partial regulators which will look half like the conformers and half like the regulators. But you know what? Sometimes all of this conforming and regulating is just not enough for some organisms. So they end up choosing a few unique ways of surviving. If the surroundings of an organism remains too stressful but for a short period of time, then the organism ends up migrating or becoming dormant. Many animals like some birds and whales, they move or migrate to tropical regions to escape the harsh winters in the north. Kind of like how we move away from Delhi to Shimla to escape the heat. However, once the stressful period of time is over, these animals return to their original habitats. Another way of dealing with stressful environments is to sleep. Not the usual 8-hour long sleeps that we are used to but sleeps that can last for months. Some organisms, including bacteria, fungi and even zooplankton for that matter, go into a state of dormancy where they suspend all of their metabolic activities for a short period of time. Now there are various types of dormancy seen in different animals. For example, bears undergo something called hibernation during the winters when it's too cold and the food supply runs really low. Meanwhile, some snails and fishes undergo another type of dormancy called estivation and they do so in order to escape the extreme heat and desiccation. So, to sum it all up, evolution came up with two main strategies for animals to survive drastic environments. They can either regulate or they can conform. And if these two things don't work, then they can always migrate to a different place or suspend their metabolic activities for a short period of time. And if none of these work, will the organism go extinct? Probably. But that doesn't mean life wouldn't prevail at all. Evolution is always trying to introduce newer ways or newer adaptations to make sure that life continues to go on and on.