Adaptation to the Environment as a Way to Ensure Ecological Survival

An ecological niche is the relationship between an organism and its surroundings to ensure its survival and includes the physical habitat, activity pattern, and environmental conditions. Physical habitats are the natural environment an organism lives where resources and shelter is provided. Environmental conditions are the biotic (living) and abiotic (non-living) factors that affect survival. Humans and blue whales have a gas exchange system and an internal transport system, both of which are adaptations that work together to increase their survival in their habitats.

Humans are terrestrial mammals found in houses. Although humans are at the top of the food chain, we still have challenges within our physical environment. One biotic factor is diseases that cannot be controlled but can be cured using resources available. The abiotic factors (eg. temperature, O2 concentration, water) are all necessary for survival as they ensure respiration occurs to produce the energy needed for liver function. Humans have adapted well to their environment as they have control over resources, minimizing the effect of biotic and abiotic factors. For example, when the temperature is too low for biological reactions to occur we have heaters to bring our temperature back up. However, since humans are larger mammals, the surface area to volume ratio is too small for respiration to function alone for survival.

Gas exchange is necessary for humans as it ensures that we have sufficient amounts of oxygen to carry out our way in life. It is done by inhaling air through our nose or mouth, trachea, bronchi, bronchioles, and into the alveoli where gas exchange occurs. The O2 inhaled is diffused into the blood cells and delivered to cells for respiration and CO2 gas diffuses into the alveoli to be exhaled. A behavioural adaptation of humans is that we ventilate air to obtain O2 and get rid of harmful gases like CO2 by the contracting and relaxing of the diaphragm to change the air pressure in the lungs, allowing the inflow and outflow of air. Humans must continuously ventilate as our lungs cannot store O2 for long periods of time and the air we breathe is only 21% O2 and 79% nitrogen and other particles.

Mucus is a sticky substance physiologically produced by goblet cells lining the airways to trap any dirt and microorganisms in the inhaled air. Cilia is a structural adaptation that also lines the airways and moves back and forth to sweep the mucus up the throat or down to the stomach to prevent infections caused by bacteria entering our bloodstream. Alveoli is also a structural adaptation of tiny sacs found at the end of bronchioles and is the site of gas exchange. They must be moist to allow O2 molecules to dissolve fast for efficient gas exchange which is why they are found deep within the body to prevent evaporation. Another aspect is that there are approximately 600 million alveoli in our lungs which increases the surface area to volume ratio so more O2 and CO2 molecules can diffuse through and increase the gas exchange rate. Alveoli are one cell thick which gives a shorter diffusion distance for O2 and CO2 molecules so the gas exchange rate is more efficient.

Ventilation, mucus, and alveoli all increase the efficiency of O2 diffusion from the gas exchange system to the internal transport system. The internal transport system is the transportation of O2 molecules from the alveoli in lungs to tissue cells around the body. The red blood cells are a structural adaptation that has few organelles and lacks a nucleus to make room for the 280 million hemoglobin molecules. Each hemoglobin binds to 3 O2 molecules to allow more O2 to be delivered to organs. Another aspect of red blood cells is they have a biconcave shape to increase the surface area for the diffusion of O2. Another structural adaptation is the capillaries that are one cell thick and lack muscle and elastic walls to shorten the diffusion distance so O2 can diffuse into the surrounding cells more efficiently. Capillaries are numerous and highly branched to increase the surface area of diffusion across more cells, allowing more O2 to diffuse through. The heart-pumping oxygen-rich blood is a behavioural adaptation so O2 can be distributed to the cells to carry out life functions. During exercise is a physiological adaptation as O2 is being consumed faster so an increased heart rate allows more blood pumped to muscles. The adaptations of red blood cells, capillaries, and the heart all maximize the amount of O2 transported around the body.

Blue whales are marine mammals found in cold oceans like the Arctic and Antarctic Ocean and share their habitat with other marine animals. Blue whales feed on krill during summer and migrate to warmer waters in winter. Biotic factors of blue whales include predators, food supply, and competition. Blue whales have no predators in the water but there have been records of orcas attacking them and whaling has threatened the species’ extinction. Their diet mainly consists of krill and is shared with other species. Since blue whales are large mammals they scare off smaller species and can feed more, giving them no competition for food. However, if the food supply is low, then competition between species will increase. Abiotic factors (eg. temperature, water, O2 concentration) are all important for survival. Blue whales migrate to warmer waters in winter for the mating season as cold temperatures are unsuitable for calves while adult whales possess blubbers (fat layer) to stay warm. Water is highly essential as it is their main source of travel. However, due to the whale’s large size, diffusion of O2 cannot efficiently diffuse through their skin.

Gas exchange in blue whales has the same purpose as humans; to diffuse O2 into the body for life functions. Whales do this by inhaling through two blowholes which go into the trachea, bronchi, bronchioles and alveoli (site of gas exchange). The blowholes are structural adaptations located on the top of their heads which allows them to ventilate by using less energy to lift a small amount of body. The trachea attached to the blowholes is separated from the esophagus to avoid water from entering their lungs when feeding which could cause them to drown so they adapted their behaviour by swimming to the surface to breathe. Blowholes have flaps that closes when relaxed to stop water from entering the lungs which could stop the gas exchange and damage organs.

Blue whales have structurally adapted by having collapsible lungs that allow rib cages to fold down when they exhale before diving to reduce the air inside the lungs. This is so the nitrogen in the air cannot dissolve into their blood as pressure underwater increases when they dive. A physiological adaptation of blue whales is when they dive and organs undergo anaerobic respiration due to low O2 levels, allowing them to produce enough energy to survive. They have adapted high toleration of the lactic acid and CO2 concentrations produced, enabling them to submerge underwater for longer without suffering. Another physiological adaptation is the hemoglobin in blood and myoglobin in muscles that stores O2. Whales have more red blood cells than humans, there is more hemoglobin available to store O2, allowing whales to have enough O2 to carry out anaerobic respiration when diving.

The internal transport system in blue whales allows the movement of O2 into organs for life function and survival. A structural adaptation is a heart that is found between the lungs and pumps blood to the rest of the body to distribute O2 and removes CO2 (wastes) from the body. One aspect of the heart is the septum that separates the left-hand side (oxygenated) and the right-hand side (deoxygenated) of the heart to avoid mixing and maximize O2 distribution. Another aspect of the heart is the physiological adaptation of a double circulatory system which includes the pulmonary circuit (right-hand side) and the systemic circuit (left-hand side). The pulmonary circuit pumps deoxygenated blood into the lungs for gas exchange of O2 and CO2 while the systemic circuit pumps to distribute O2 in body cells and carry back CO2. The heart also has 4 valves (mitral, tricuspid, aortic, pulmonary) that controls blood flow efficiency.

The mitral and tricuspid valves control blood flow from the atria to the ventricles while aortic and pulmonary valves control blood flow from ventricles to the body. Another structural adaptation of blue whales is their arteries. Arteries in blue whales are large, thick, and muscular blood vessels that pump oxygenated blood around the body except for the pulmonary artery which carries deoxygenated blood to the lungs. Arteries in blue whales must be large to transport a large amount of oxygen-rich blood around the body for life functions and are thicker and more muscular than veins to withstand the high pressure as it is pumped away from the heart.

Both the gas exchange system and the internal transport system work together to enable both humans and blue whales to live successfully in their way of life because the respiratory system in either mammal cannot efficiently distribute sufficient amounts of O2 to the cells to meet the mammal’s metabolic needs. This is done by the movement of the diaphragm, intercostal muscles, and heart increasing the gas exchange rate, and the blood vessels connecting the lungs, heart and body cells transporting the diffused O2 and CO2. The diaphragm and intercostal muscles contract, allowing airflow into the lungs through the nasal cavity, trachea, bronchi, bronchioles, and alveoli where the O2 dissolves and diffuses into the surrounding capillaries and into the double circulatory system.

Both the heart of humans and blue whales have 4 chambers with thick muscular walls that contract to pump out blood. The left and right atria receive blood while the left and right ventricle contracts to pump blood away from the heart. The heart works together with the pulmonary blood vessels (artery and vein) so the red blood cells can obtain O2 to transport around the body in exchange for CO2 to be exhaled. Since alveoli have high concentrations of O2 and low concentrations of CO2 while the surrounding capillaries have low O2 concentration and high CO2 concentrations to allow effective diffusion between the two systems. This increases the gas exchange rate as we need to continuously ventilate, allowing the heart to constantly pump which maintains the concentration levels in alveoli and blood vessels so our body cells can carry respire and make energy for life functions to survive in their way of life.

The gas exchange allows the exchange of O2 and CO2 between the respiratory system and the internal transport system. This is an advantage to mammals as its adaptations allow O2 to diffuse into the bloodstream for cells to carry out life processes while also releasing toxic CO2 so it does not build up in the body and damage vital organs. Another advantage of gas exchange is the lung’s large surface area to volume ratio due to the millions of tiny alveoli. This allows for more O2 to diffuse at the same time which makes the system more efficient as mammals obtain sufficient amounts of O2 for life functions. A limitation is ventilation as not all O2 inhaled reaches the gas exchange surface, resulting in humans only exchanging 10-15% and whales exchanging 80-90%. This means that not all the O2 inhaled is absorbed by the blood. Another limitation of gas exchange is that it limits mammals to living on land as the system requires air. While whales have adapted to life underwater, they still have to come to the surface to breathe and can only hold their breath for a limited time.

Internal transport allows the delivery of O2 and CO2 between the gas exchange system and cells. This is advantageous to mammals as its adaptations allow O2 to be absorbed by the blood and distributed to all cells in the body, meaning all cells large mammals like blue whales can still get O2. Another advantage is the closed circulatory system meaning the blood flow stays inside and can adjust to efficiently deliver O2 to important organs especially in blue whales as their bodies are larger. A limitation is the limited O2 storage, meaning when there is no constant supply of O2 that blood can absorb and deliver to vital organs for respiratory and life function. Another limitation is when the climate changes and air pressure decreases, resulting in less O2 being inhaled, absorbed and distributed for life functions and survival.