In order to survive, an organism requires nutrition, water, oxygen, a habitat and proper temperature. A lack of any of these fundamental necessities, proves detrimental to an animal's survival at most and its growth and development at the very least. Of the five, the habitat is a prerequisite of sorts, for the other four are found within an animal's habitat.
The most important nutrient for survival is water, according to the University of Florida's Institute of Food and Agricultural Sciences Extension. Water is the medium in which all chemical reactions take place within an animal's body. If an animal loses one-tenth of its water for any reason, the results are fatal. Water also functions in excretion of wastes, regulating body temperature and transporting food.
In terms of diet, three types of animals exist: carnivores, herbivores and omnivores. At a fundamental level, food provides energy for animals. Adaptations enable all animals to get food. Toothed herbivores, for example, have large, flat, round teeth that help them grind plant leaves and grasses. Some carnivorous animals, such as bears, dogs and the big cats cats) have sharp canines and incisors for chewing through meat with ease. The digestive systems of animals have proteins known as enzymes that break down food and convert it into energy.
All animals must breathe in oxygen in order survive. Land-dwelling species receive oxygen from the air, which they inhale directly to their lungs. Marine and freshwater species filter oxygen from water by using their gills. Oxygen is also important in destroying harmful bacteria in an animal's body without sacrificing the body's necessary bacteria.
External temperature is a major factor in animals' survival. Of the vertebrate groups, amphibians, reptiles and fish -- animals said to be cold-blooded -- take on the temperature of their environment. Most have thin skin. Birds and mammals, on the other hand, which are termed warm-blooded, can regulate their own body temperature. However, some mammals, such as bears, gophers and bats, hibernate during the winter to avoid colder temperatures. Hibernation allows animals to live off stored body fat and drop their body temperature to about 50 degrees Fahrenheit.
Each animal needs a place to live -- a place where it can find food, water, oxygen and the proper temperature. A habitat also offers shelter from the elements, protection from predators, a mate for reproduction and a place to rear its young. Some examples of habitats are deciduous and coniferous forests, wetlands, deserts, savannahs, rainforests and the ocean. Some animals use multiple places to their advantage. For example, some birds fly over grasslands searching for food but build their nest in dense forests or treetops.