 Isn't it fascinating how all of us organisms somehow figured out a way to adjust to our surroundings? I mean look at this polar bear over here. It has fur and thick skin to keep it warm from all of the snow. Then the snake here can produce venom to defend itself. Then bears hibernate to escape harsh winters. Birds have hollow bones which help them in flying. Birds have genetic mutations to help them thrive in the mountains. Meanwhile there are some fish which have anti-freeze proteins to keep them from freezing in the Antarctic waters. And then we have some bacteria which straight up live in hot springs because that's their usual habitat. It's downright crazy to think about how we have evolved to fit into our environments. But did you notice something? All of these changes, these adaptations are not exactly of the same kind. I mean think about it. This polar bear has an adaptation where it has fur and thick skin. And then we have this another adaptation over here which talks about genetic mutations. I mean these are completely different things. But then if you look a little bit more closely there are some adaptations here which have some similarity like these hollow bones of birds and the fur and thick skin of the polar bears. They're not exactly the same but they're not as wildly different as the mutations. How if you ask, so think about it in this way, the fur and the thick skin of the polar bear is a part of its structure, it's a physical feature. In the same way the hollow bones are a part of the bird's skeletal structure. So these are both structures you can say. So keeping that in mind we can actually kind of group these two adaptations together and call them structural adaptations. Structural because it's talking about, it's related to the structure of the organism. It's a physical part of that organism. So these are structural adaptations. Now you'll find a bunch of these structural adaptations in the animals which live in snowy regions like the poles. So let's have an example too right over here. This is an arctic hare. Let's look at it a little bit closely. So this is an arctic hare and this animals like these, like this arctic hare right over here, they have shorter, thicker body parts. Like if you look at their limbs they're pretty short right, they're short and thick. Why? Because they have a much less surface area compared to their volume and this kind of reduces the heat loss. So it keeps them warm. This theory where it talks about that having a smaller surface area to volume ratio preserves heat. This is an actual theory and we call this theory Alan's rule. There's actually a name for it. So Alan's rule talks about how having a smaller surface area to volume ratio can reduce heat loss. Actually you have to write it down. It'll be that the surface area to volume ratio if this ratio is less that means heat loss will also be less. This is what Alan's rule is and this is what these animals they follow as well. So that's how they have all of these structural adaptations which help them to retain body heat. Now structural adaptations aren't just limited to animals only. You will find structural adaptations in plants as well and a very famous plant is the cactus which is not in the right place. So let's move this a little bit. Okay there we have it. So this cactus right over here has many structural adaptations. Again let's take a closer look. Now cacti or cactus they have spines right. Now these spines they are modified leaves and they are modified in a way to reduce transpiration because these cacti they flourish in the deserts right the scorching heat of the deserts and they cannot afford to lose a lot of water. So these spines they kind of reduce water loss through transpiration and that's not all. Thick succulent stems that you see these are modified to store water and photosynthesize as well. In fact the way cactus or cacti photosynthesize that way is also different from how normal plants photosynthesize. So it's aimed at saving water that photosynthetic process you find in cactus is also aimed at saving water. So they have multiple structural adaptations to make sure that water loss is minimal given the kind of habitat they live in. Alright so we have two of these adaptations out of the way. We have decided we have organized them and we now know that these two are structural adaptations. Now let's take a look at the other adaptations that we have on the screen over here. When we start talking about these other adaptations that we have on the screen do you think you can add one of these under structural adaptations like you can call any of these adaptations as a structural adaptation? You can pause your screen here and actually think it through. Well I couldn't find any of these adaptations that I could place under structural adaptation because none of these kind of directly relate they are not related to the structure. So maybe what we can do now is that we can find similarities between these adaptations between each of these adaptations. So let's take a closer look again. So let's start off with our bear which is hibernating over here. So a bear hibernating is something that a bear has to do right. I mean it's kind of like an activity. It's going to hibernate in response to the harsh climate, the harsh cold climate. So it's slightly different from an adaptation, a change directly in the structure. So we can't place that under structural adaptations. But these other adaptations, the snake venom being produced or the antifreeze proteins, even the mutations and the bacteria that can thrive in the hot springs, all of these things, all of these adaptations, they are happening inside the organism's body. Think about it, the venom is getting produced inside the snake. The antifreeze proteins are being produced inside the fish. The mutations are in the genes again inside the Tibetans and the bacteria that can thrive in these hot springs are due to some enzymes which work faster and better at high temperatures. So those enzymes are also being produced inside the bacteria. So these adaptations, the snake venom, the antifreeze proteins, the Tibetans with the mutations, the bacteria, all of these are altered internal functions of this organism. So you can call these adaptations as functional or you can also call them physiological adaptations. Now why physiological? Because all of these adaptations are talking about internal functions that are being done inside of these organisms, all of the venom, the proteins. So think of it kind of like the release of certain compounds like toxins or venoms or a higher or lesser production of some kind of protein or some other compound. So all of these things are happening as an internal function. So that is why these adaptations are called functional or physiological adaptations. A rather intriguing example of this adaptation is seen in the people who live really high up in the mountains. So let's focus on the Tibetans here for a minute now. As you move higher up the mountains, the air starts to get thinner or in a way you can say the oxygen levels start to drop. So because of that when you and I, if you and I would move to a place like Tibet, our bodies would have to adjust to the low levels of oxygen over there and it would do so by increasing our breathing rate and producing a lot of red blood cells so that our body gets the enough amount of oxygen it needs. But the problem in this strategy is that if there are too many RBCs in our blood then the blood starts to get very viscous or very thick and that can easily lead to clots and heart failures which is a very dangerous thing clearly. So we cannot have that. Then how are the Tibetans not falling sick at every minute of every day? Why aren't their blood getting thicker or why aren't they suffering from any kind of heart disease? Tibetans have two things that us plain dwellers don't have. One is that they have this gene mutation which doesn't allow the RBCs to increase the way our RBCs do. So RBC production is comparatively much less and this is what prevents the thickening of blood because if there's not enough RBCs the condition would never arise. And the second thing that these guys have is that they have a much higher the normal concentration of nitric oxide and this is a chemical compound which helps in the dilation of blood vessels. So their strategy is something like this. They breathe very quickly so their breathing rate is pretty high so that gets them more oxygen. There's the gene mutation stops the higher production of RBCs which prevents the thickening of blood and then they have a much higher concentration of nitric oxide which causes their blood vessels to dilate for a smoother flow of blood. So all of these things and mind you these are permanently evolved physiological adaptations. The gene mutation and the concentration of nitric oxide being higher. All of these are physiological adaptations and all of this is what helps Tibetans breathe better even at such high altitudes. And when I say high altitudes I mean like 13,000 feet high from the sea level. Okay so now we have only one adaptation left that we haven't really talked about so let's go back to our hibernating bears now. Now we've already mentioned this hibernating is kind of like an activity. It's something that the bears tend to do in order to escape colder climates right so it's an animal behavior you can say it's it's a it's a way it's a certain way the animal behaves in response to something drastic like a very cold climate or something like that and there are other ways I mean there are similar ways that animals behave as well for example there are some birds that migrate to better areas to escape again colder harsh climates and then you'll also see some garden lizards they bask in the sun to raise their body temperature so all of these things these are very specific animal behaviors so these types of adaptations all of these the migration or we're gonna need a different color for this so let's pick out another color so the whole migration and the basking in the sun all of these are specific animal behaviors and they are also adaptations so we call these things as behavioral behavioral adaptations so all of these these are behavioral adaptations they are associated with a very very specific innate behavior that these animals are born to do these these are behaviors that that's kind of ingrained into them it's not something that they pick up it's something that they just know they have to do in order to escape certain things or in order to react to their surroundings now we've been talking about this extensively all this time we've been talking about adaptations and the different types of adaptations which are available and everything but if you really had to think about it how exactly would you define an adaptation so you've been talking all about it but how would you define it how would you define what an adaptation is alright so some people like to think of adaptation as a characteristic feature or you can call it a trait which kind of makes it easier for an animal to survive or reproduce in its environment so it's a characteristic feature or a trait that's how some people have defined it so kind of like do you remember the peppered moths that we talked about during the Industrial Revolution that they were able to camouflage that was an adaptation the way that they could blend into the tree trunks and escape predation by camouflaging so that was a trait so some people call that camouflage as an adaptation and then there are some scientists who think of adaptation as a process a process that happens when organisms in a population accumulate adaptive traits so think of the peppered moths once again except this time think of the entire process the light colored moths they couldn't stay hidden right so they got eaten up by the birds but the dark colored moths they were able to camouflage and they stayed hidden and because the light colored moths got eaten up pretty quick and they couldn't reproduce the population of the dark colored pepper moths went up quite easily so this entire process of how the dark colored moths eventually gained the upper hand and they became the dominant organism with this advantageous trait that it had this entire process is what some people call as an adaptation and that's all about how you can define adaptation and the different types of adaptations which are available in different organisms around the world