Warm Blooded vs Cold Blooded Animals
The whole animal kingdom could be divided into two major categories depending on the maintenance of the body temperature i.e. warm-blooded and cold-blooded. Later evolved animal groups such as, birds and mammals are warm-blooded, while the rest are cold-blooded. However, there are some mammals with cold-blooded characteristics and some glamorous fish species with warm-blooded characteristics. The basic differences of these two types of animals are discussed in this article with referring to some important examples.
Basically, the mammals and birds are warm-blooded. They can maintain their body temperature at a stable level despite changes in external temperatures. The term warm-blooded is a general reference because, there are three aspects of thermoregulation in warm-blooded animals; endothermy, homeothermy, and tachymetabolism. Controlling body temperature internally via metabolic and muscle shivering activities, is known as endothermy. Maintaining the body heat in a stable level regardless of the external temperature is homeothermy. In tachymetabolism, body temperature is always kept at a higher level by increasing the metabolism, even during resting. The warm-bloodedness is a great advantage for the birds and mammals as it makes them active throughout the year where the environmental temperature fluctuates drastically with seasons. According to Palaeontology, many bird and mammal species have been able to survive in Ice Ages where, most of the reptiles died.
In cold-blooded animals, the internal body temperature is not at a constant level but, it is a changing figure according to the environmental temperature. They are also known as ectotherms, where, the required body heat is gained by behaviours such as, sun basking (e.g. crocodiles, snakes). Therefore, the controlling of body temperature is done by external means in ectotherms. Some cold-blooded animals are capable of functioning over a range of temperatures, and they are known as poikilotherms (e.g. some fish and amphibian species). Bradymetabolism is the other aspect of the cold-blooded animals. They are capable of changing metabolic activity according to the environmental temperature where, they hibernate during winters and active in the summers. Palaeontology reveals that the dinosaurs were once thriving on the Earth became extinct after an Ice Age. That was due their cold-bloodedness. However, there are some advantages of being a cold-blooded animal viz. there won’t be a need for food during hibernation as, in winter season the food sources are scarce. Some cold-blooded animals have remarkable adaptations to maintain the body heat, especially in diving reptiles and some amphibians (bullfrog). Diving reptiles have a circulatory mechanism to save warmer blood inside the body while diving. The bullfrog secretes mucus when the sunlight is intense to keep the body cool via evaporation.
Warm-blooded Vs Cold-blooded Animals
In reviewing these two types of animals some interesting issues raised; physiologically adapted cold-blooded reptiles and amphibians, they look somewhat like warm-blooded animals.
In contrast, some bats and birds have shown ectothermic characters while sharks and sword fish showing endothermic characters.
Sharks are able to keep the temperature around eyes and brain at a higher level than the ambient temperature through circulatory mechanisms hence, they could spot and plot an attack if a prey comes closer.