 Dear students, in this module, we shall discuss the principles of conformity and regulation. These are two categories of animal responses to changes in their external environment. The conformer animals are those which are unable to maintain homeostasis for an environmental variable. These animals conform to that external variable, i.e. they compromise that they are in external conditions. So, we will follow this. The degrees to which the conformers conform depend on their level of survival. That depends on the tolerance level of body tissues to that variable. We shall take a few examples of conformers. The conformers or conformation depends on the changing environmental variable. For example, if an animal conforms to water and salt levels that is called osmo conformer. The animal which conforms to the level of oxygen is called oxy conformer and the animal that conforms to temperature change is called thermo conformer. We shall take the example of osmo conformer first. The osmo conformers do not actively adjust their internal osmotic state. In these animals, their body tissues are kept isotonic to the external environment. They show increase in body fluid salinity in hypertonic solutions and decrease in body fluid salinity in hypertonic solutions. Oxy conformers consume oxygen when there is more level of oxygen in the air. They if the oxygen availability is there is no oxygen availability, they cannot regulate their body conditions to the lower level of oxygen. Similarly, the thermo conformers conform to the temperature of the environment. As the environment warms or cools, the animal's body also warms or cools in the same way. The outside temperature will work, the animal's temperature will also work, if the outside temperature increases, the animal will get heated up. In contrast to conformers, the regulators use internal control mechanisms to regulate their internal conditions. In spite of fluctuations in the external environmental variables, so these animals maintain homeostasis. The regulators are also of various types depending on the environmental variable. They can be thermo regulators, if they are regulating their body temperature. They can be oxy conformers and they can be Osmo regulators, thermo regulators and oxy regulators. The Osmo regulators maintain their body fluid concentration that differs from that of the environment. They can maintain the concentration of body ions and body fluids in hypotonic or hypotonic environments. If the environment is hypotonic, they will maintain the salt concentration in their body. If the environment is hypotonic, there are more salts out there, they will regulate the salt concentration and will not increase the salinity in their tissue fluids. The Osmo regulators adopt the strategy to regulate the amount of water in their tissues. They discharge excess water in hypotonic environments and they conserve water in hypotonic environments. In hypotonic environments, where there is more salt out there, they maintain the water concentration in their body fluids and they conserve water. Otherwise, water has a tendency to move from its lower concentration to its higher concentration to its lower concentration, that is from the body to the outside environment. This is the conservation of their Osmo regulatory strategy. The oxy regulators maintain their oxygen consumption at steady level, whether the oxygen level is higher or the oxygen level is lower. If the oxygen level is higher in the environment, then a regulator will use a required amount. And if the oxygen level is lower in the environment, then the animal keeps the utility full, and in order to achieve the oxygen level, it takes changes in the body. This is oxy regulation. However, if the oxygen level is higher in the environment, then the animal's systems are not able to complete the requirement, then as a result, the animal tries to be an oxy conformer. The animal tries to be an oxy conformer, and maintains its systems at a low oxygen level until and unless it dies. Thermo regulators regulate the temperature of their body. Especially, in the environment, the temperature variations are taking place. If the temperature is lower in the environment, then it keeps the temperature of the body at a higher level. And if the temperature of the environment is too high, then it can cool down the temperature of the body. This is homeostasis. This is what homeostasis is called. That is temperature-maintaining animals. Dear students, An animal cannot be conformers or regulators for all the variables. An animal is conformer for one variable and may be a regulator for that variable. And if an animal is regulator for some particular variable, he may be conformer for other variables. For example, fishes are thermo conformers, they don't regulate the temperature but they maintain the concentration of water and salts in the body from the Asmore regulators.