Animals need certain things to survive. Living in the wild is often challenging, and animals require things such as a place to live, food, and water to stay healthy and to raise their young.
There are four main necessities for animals:
Within these parameters, animals also need to maintain their body temperature and have suitable air to breathe or water to swim in.
All life on Earth requires food to survive. Food provides energy and vital nutrients to ensure normal bodily processes can occur.
The smallest animals feed on bacteria and other microscopic organisms. There are three types of animals: herbivores, carnivores, and omnivores, each with its adaptations.
Herbivores graze on vegetation for their nutritional needs. Typically, herbivores are found in grassland, dense woodland, or rainforests and marshes. Here, plants grow in abundance, providing all the grasses, leaves, and fruits a herbivore needs to survive.
Herbivores have mobile lips to grasp their food and large flat teeth to grind the plant matter down. They will also consume specific plants such as fungi as they carry bacteria capable of digesting cellulose.
Cellulose is the molecule that forms the cell wall of all plant matter, but herbivores do not produce the enzyme needed to break down cellulose. Instead, they have a symbiotic relationship with fungi and other bacteria that do produce cellulase.
Herbivores usually have to eat a large amount of food each day to gain the required nutrients.
In North America, there are hundreds of herbivorous species, including:
- Fruit bats
Carnivores eat other animals. Typically they hunt herbivores. However, some large carnivorous animals will eat other carnivores.
There are also hundreds of omnivorous species, meaning they eat both vegetation and meat. This includes animals such as:
In contrast to herbivores, carnivorous animals have sharp teeth to grip their prey, pierce the skin and rip the meat from the carcass. Some carnivores only eat once every few days as their prey provides a lot of energy, protein, and fats.
Carnivores will eat almost all the animals, including the organs, skin, bone, and even the stomach contents. This is called tripe, and it is a popular cooking ingredient in many parts of the world.
Omnivores are animals that feed on both vegetation and other animals. In North America, there are several omnivorous species, including:
- Gray fox
- Red fox
While omnivores generally have a heavier meat proportion to their diet, they still rely on plant matter, especially during the summer when vegetation grows quickly and over large areas.
Some animals, like bears and vultures, are scavengers. They are often seen eating dead animals that another animal has killed. It is also common to see scavengers feeding off roadkill.
Being an omnivore is advantageous because they can survive on plants and fruits if there are no prey animals in the area. A strict carnivore would starve in this exact situation.
Water is essential for all life, both plants and animals. It makes up as much as 70% of an animal’s body. Without water, none of the body’s chemical reactions would take place. This includes the production of new red blood cells, skin cells, production and excretion of waste, digestion, and body temperature regulation.
Dehydration is a fatal condition for wild animals. The longer an animal goes without water, the more serious its health will become. Their digestion will slow down, waste will not be filtered and excreted efficiently, and they will be unable to maintain a stable body temperature. Eventually, their organs would shut down, and the animal would die.
This is true even for animals in desert habitats that can survive longer without water. They, too, need to find a water source at some point. Droughts in desert areas can cause the deaths of thousands of animals.
Shelter is essential for several reasons. A shelter could be a slight hollow in the ground, a tree, or a complex den. Animals use shelters for:
- Protection of offspring
- Protection from predators
- Protection from the elements
Most hibernating animals will dig a den or burrow underground. Some build a nest in a tree hollow. Small animals will build nests in birdhouses or garden sheds in residential areas.
A den or nest offers good protection from predators, especially for animals raising young. Birds often become aggressive during the breeding season, fiercely guarding their nest against perceived danger.
Bears dig dens in late summer or early fall, ready for hibernation. The shelter is usually big enough for the mother and her cub to fit. Due to its small size, it keeps a stable temperature and can easily hide from potential predators who may see a bear cub as easy prey.
Animals living in harsh conditions will use their shelter to guard against the elements. In desert environments, a well-placed burrow will maintain a cool temperature for an animal to avoid the daytime heat and a safe place to sleep.
In cold climates such as the Arctic, a den or even a shallow dug patch of snow offers protection from strong winds. Seals will often build shallow nests on ice floes to shelter their pups from severe weather during the breeding season.
Animals that live in herds need a large amount of space to accommodate all group members. Some animals, like bison, are pretty large, so they require even more space. A group can be a family group of parents and offspring or several family groups together.
Too many animals in a small space can quickly spread disease, and animals cannot get away from one another to avoid fights. This is why most herding animals live in open areas like grasslands.
Some animals are solitary, only coming together to breed. Many seal species are isolated during the fall and winter but form large groups during springtime when males spar to win rights to mate with the females.
Other species will seek out a single partner rather than forming a group. Once breeding is over, they separate again. For solitary animals, only the mother is involved in rearing the offspring.
Habitats with large open spaces give animals the ability to find privacy from other animals. The same is true for arboreal animals (those that live in trees). The more trees there is, the more opportunity for privacy and more nesting spots.
The territory is also important. Solitary animals tend to establish their territory and aggressively defend their home range. A large area provides enough space for several animals to have their environment.
In cases where the population is too great for the environment, there is not enough space for every animal to have their territory. In this case, one of two things will happen.
Either the territory size of each animal will shrink to accommodate all the animals, or fights will break over the available space. Wherever possible, animals try to avoid fighting as it risks injury or death.
Smaller territories mean fewer nesting sites and a reduced number of food sources, so reducing an animal’s territory size can severely affect its ability to survive.
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Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.