The metabolic rate of an organism is commonly defined as the amount of energy that is metabolized through food or oxygen uptake per unit of time. The metabolic rate for organisms plays a fundamental role in some biological processes and in the general maintenance of the organism. There are many ways to measure metabolic rate, but the most common way is to measure the amount of oxygen produced provided there is no anaerobic metabolism. It can be hypothesized that the metabolic rate increases with body mass. This will be done by preparing four vials ensuring that there is soda lime to absorb carbon dioxide during the organism's respiration and that there is gauze so that the invertebrates i.e. snail, cockroach and crab do not have contact with the soda lime and limit its the movements. The fourth vial is used as a control. The vials should be acclimatized and then placed under a water bath with a stopper and pipette to cover the opening of the vial and so that oxygen consumption can be noted through changing volume readings. These readings can be used to determine specific oxygen consumption (μl O g^(-1) h^(-1)) and the average volume of oxygen produced. Although the specific oxygen consumption values ​​did not conform to the usual assumption of the elephant and the shrew (specific oxygen consumption is inversely proportional to body mass) the average volume of oxygen produced increased with increasing mass consequently l The hypothesis is accepted and it is concluded that the mass of an organism and its metabolic rate are directly proportional to each other. Metabolic rate can be defined as the total amount of energy that has been metabolized through food or oxygen uptake by an animal per unit of time (Willmer et al., 2005). This energy p... middle of paper... errors may have occurred during the study because we were not highly trained for this type of experiment and there may have been a lot of human errors. The animals where perhaps they were in a state of shock upon arrival in the laboratory, the acclimatization period was perhaps too short, pipettes of different sizes were used thus creating different readings, so as not to compare a cockroach to other animals because it breathes very quickly in temperature environment and the water was at room temperature and perhaps the animals were not exactly in resting conditions. We therefore conclude that the rate of oxygen consumption is inversely proportional to the body mass of that particular animal. In the future, to make the study more accurate, the animals must be almost the same that can be used to study this ideology, such as mammals, amphibians or reptiles, makes most of the factors constant.