Warm and cold-blooded animals:
Warm-blooded animals are animals that are endothermic. This means that their main source of warmth is generated by themselves. These include birds and mammals. Cold-blooded animals rely on the temperature of their surroundings to determine their body temperature. These are ectothermic, and include almost all animals, excluding mammals and birds.
Whale:
Whales are large marine mammals that have to retain a mammalian temperature of 37 º Celsius in waters as cold as 4 º Celsius. They have various methods of doing so, such as a thick layer of blubber underneath their skin, which acts as an insulator and reduces conduction, because blubber is a poor conductor of heat. Whales also have decreased breathing rates, which also helps prevents the loss of internal heat.
Whales will also adjust their circulatory system in order to conserve or expel body heat so that body temperature can be maintained. This is done by increasing circulation in the flippers of the whale so that the excess heat is transferred to the whales flippers. The whale will then raise its flippers above the surface of the water and radiates the excess heat away. This is why whales are seen ‘jumping’.
Snakes:
Snakes are reptiles that often live in hot climates. They are cold-blooded, and have to rely on their surroundings for a stable body temperature. They warm their bodies up by basking in the sun, or when they want to lower their body temperature, they will seek places that are cooler and lay in them, i.e. shade under a rock or a hole in the ground. In order to do these things they have special heat sensors, which aside from helping them hunt, also assists them in the search for a place which will help them reach their desired temperature.
Color can also play a role in the thermoregulation of a snake. Because lighter colors are poorer absorbers of heat, a snake living in a hot climate will often have a lighter color, to minimize heat absorbed through radiation.
Birds:
Birds are feathered animals that fly. They can live in a variety of different habitats, but they all generally use the same methods of conserving a steady body temperature.
In order to conserve heat, lower temperatures will cause the muscles of the bird to contract, creating ‘Goosebumps’, which in turn make the feathers of the bird stand up. When the feathers are stood up, more air is caught in between them, and because air is a bad conductor of heat, and a good insulator, the bird will remain warm. The bird will also increase its plumage in colder seasons, adding more to the insulating layer that it wears.
Heat loss through evaporation in birds can only occur through the respiratory system, as birds have no sweat glands. They pant, causing warm air to make the moisture in their lungs evaporate and cool them down. They also flutter their gular area rapidly as a means of losing heat through evaporation.
Rabbits:
Rabbits have to maintain a temperature of 21*celcius. In order to lose heat in hot temperatures, they stretch out in order to increase their area and lose heat through convection and radiation. Rabbits also pant, so they can lose heat through evaporation. They can also dispel body heat through nasal mucosa. The ears of a rabbit are also an important means of losing extra heat. Blood is pumped into the ears, where the surface area is large and the heat can be radiated away. This is very similar to the tactic that whales use.
Humans:
Humans are mammals; they have very little body hair and often adjust the temperature of their surroundings in order to remain at a comfortable temperature. However, when exposed to uncomfortable climates, they will take initiative in order to remain at their preferred temperature.
In cold surroundings, humans, like birds will also develop goosebumps. These, however are slightly less effective, seeing as humans have much less body hair in which to trap air. Fat stored in the body of a human also serves as a way to contain warmth, much as blubber in a whale, although warmth is not the primary function of fat, as it is more for storage of excess glucose attained by over-consumption.
The human will also rub its hands or other body parts together, creating friction, which warms those parts of the body up temporarily. Engaging in exercise in the cold will warm the muscles of the human up. In addition to that, wearing more clothes helps immensely because the clothes act as an insulator. Wearing a hat helps cut down heat lost through the head by convection.
In order to lose warmth, humans will perspire, releasing water from their body onto their skin through sweat glands. The water will then be evaporated, taking the heat from the surface of the skin with it.
Bibliography
'Heat transfer in animals' guide sheet
http://chainreaction.asu.edu/desert/digin/thermoreg.htm
http://www.uwrf.edu/biology/electives_dir/444_dir/VSmith/Page1.html
http://www.slvjh.slv.k12.ca.us/SLVJH/students/derek/kwhale.htm
http://144.90.137.57/~bfiero/tucsonecology/adaptations/thermoregulation.htm
http://www.biology.eku.edu/RITCHISO/birdmetabolism.html
http://ressources.ciheam.org/om/pdf/c08/95605277.pdf
